Micro Block 2

C. diff transmission

- shed in feces -any surface, device, or material (e.g., commodes, bathing tubs, and electronic rectal thermometers) that becomes contaminated with feces may serve as a reservoir for the Clostridium difficile spores -are transferred to patients mainly via the hands of healthcare personnel who have touched a contaminated surface or item

Coccidiodes

-"the great imitator" -a systemic mycoses causing agent that is thermally dimoprhic; a "true" pathogen -causes: coccidiodomycosis rash, multiple papules on face and neck, infiltration in bones -pulmonary manifestations may include pneumonia, pleural effusion, hilar lymphadenopathy, and/or lung nodules

Role of granuloma in Mtb immune response

-"walling off"; preventing mycobacterial dissemination -protect delicate alveolar tissues and spaces -establish a microenvironment where T-cells and macrophages can remain close -breakdown coincides with re-activation disease -site of latency

Guillan-Barré Syndrome epidemiology

-1 out of 1,000 cases of C. jejuni enteritis leads to GBS -30-40% of patients with GBS have had C. jejuni infection 10-14 days prior to onset

Tuberculosis in the U.S.

-1953 to 1984: TB incidence dropped to 9.4 cases per 100,000 -1985, the U.S. experienced a reversal of the long-standing downward trend -Large outbreaks of TB also began to be reported -1993, WHO designated TB a global public health emergency. -1994, cases in the U.S. began to decrease once again - the only country to experience a decline -2014, incidence = 3.0/100,000 (9,412 cases)

2-stages of virulence in pneumoccocus in the lungs

-1st stage is early infection: capsule and surface proteins block phagocytosis, allowing bacteria to spread in spite of inflammatory response -2nd stage: host cell damage via pneumolysin, autolysins, and other enzymes

Campylobacteriosis

-2 million cases in U.S. annually -13,000 hospitalizations, 124 deaths -one of most common causes of diarrheal disease in U.S. -ID: 500-9,000 organisms (relatively low) -incubation pd: 2-5 days -symptoms usually resolve in 1 week but can last up to 2 weeks

Botulinum toxin

-7 known serotypes (A-G); A and B are most common -8th possible serotype (H) -toxin consists of 2 protein subunits linked by disulfide bond; activated by proteolytic nicking -active toxin binds to glycoprotein or glycolipid of the neuron -enzymatic portion of the toxin is a zinc-required endopeptidase that cleaves SNARE proteins (synaptobrevin, SNAP-25, syntaxin) found in neuronal secretory vesicles

Tuberculosis: historical perspective

-8000-5500 BCE: evidence of spinal TB found in neolithic and pre-Columbian skeletons -400 BCE: Hippocratic school described disease as "pithisis" (wasting away) -circa 1680: consumption era -17th and 18th century: Industrial Revolution; TB killed 1/4 adults -19th century death rates: 1,000/100,000; 30% adult deaths in Europe -Koch discovered bacillus in 1882; named tuberculosis in 1884 (tuber = swelling or growth)

Antimycotics that disrupt cell membranes

-Amphotericin B, Nystatin -binding and affinity for ergosterol

Antimycotics that block ergosterol synthesis

-Azoles (e.g. Imidazoles, miconazoles, econazole, ketoconazole)

Relapsing Fever species (type, vector)

-B. hermsii (Tickborne, Ornithodoros hermsi) -B. parkeri (Tickborne, O. parkeri) -B. turicatae (Tickborne, O. turicata) -B. crocidurae (Tickborne, O. sonrai) -B. hispanica (Tickborne, O. erraticus) -B. duttonii (Tickborne, O. moubata) -B. recurrentis (Lousborne, Pediculus humanus humanus)

Compare and contrast bacteria and fungi

-Bacteria *prokaryotic (no nucleus) *no organelles *single-celled (can grow in chains or clusters) *varying O2 requirements *generally small and fast-growing *use antibiotics for therapy -Fungi *eukaryotic (have nucleus) *several chromosomes *cytoplasmic organelles *can be single and multi-celled (some grow both ways) *most are aerobic *generally larger and slow-growing *antimycotics are used for therapy; NOT antibiotics

Serotype B meningococcal vaccines: Bexsero and Trumenba

-Bexsero *Neisserial adhesion A (NadA) *Neisserial heparin binding antigen (NHBA) *Neisserial factor H binding protein (fHbp) *Neisserial outer membrane vesicles (OMV) -Trumenba *Neisserial factor H binding protein (fHbp) subfamily A *Neisserial factor H binding protein (fHbp) subfamily B

C. perfringens enterotoxic infections

-C. perfringens is one of the most common causes of foodborne illness in the U.S. -infected pts develop watery diarrhea and abdominal cramps within 6-24 hours (usually 8-12) -illness usually begins suddenly and lasts < 24 hours -usually no fever or vomiting; no transmission from one person to another -oral rehydration or, in severe cases, intravenous fluids and electrolyte replacement can be used to prevent or treat dehydration -antibiotics are not recommended

Campylobacter virulence factors: attachment to epithelium

-CadF binds to fibronectin -fimbriae-like filaments help with adhesion -putative adhesins: JlpA (surface-expressed lipoprotein), CapA (autotransporter protein), PEB1, major outer membrane protein

Opportunistic fungi that cause systemic mycoses in immunocompromised patients

-Candida albicans and other Candida species -Cryptococcus neoformans -Pneumocystis jiroveci (aka P. carinii) -Aspergillus fumigatus and other species -Zygomycetes

Most common bacterial pathogen for urethritis

-Chlamydia trachomatis -Neisseria gonorrhea

CDC case definition of Lyme disease

-Clinical case definition: EITHER *erythemia migrans (EM) rash ~ 5cm in diameter *at least 1 late manifestation (i.e. musculoskeletal, nervous system, or cardiovascular involvement) & laboratory confirmation -Laboratory criteria for diagnosis: at least ONE of the following: *Isolation of B. burgdorferi *Demonstration of diagnostic levels of IgM or IgG antibodies to B. burgdorferi *Significant increase in Ab titer between acute and convalescent serum samples

Co-infections from Ixodes tick bite

-Common: *Babesia microti: a protozoan causing infection with malaria-like symptoms *Anaplasma phagocytophilum: bacteria that cause Human Granulocytic Anaplasmosis -Less common: *Borrelia miyamotoi (a Relapsing Fever species) *Powassan virus

Leprosy control and treatment

-Control *treat infected individuals *incubation pd: 3-10 yrs *no longer use isolation -Treatment *combination therapy: Dapsone, rifampin, clofazimine *at least 2 yrs; may need to be medicated for life

Diagnosis of Leptospirosis

-Culture *Blood and CSF specimens - first 10 days of infection *Urine - 7 to 90 days after infection *Fletchers or Stuarts media - 30 degrees C * Detectable growth after 21-90 days *Darkfield microscopy of culture - motile, coiled cells -Serology *Most common method *MAT - microscopic agglutination test * ELISA -Clinical history/presentation * Contact with animals or water * Symptoms * Lab tests (liver function and urine protein)

Common agents that cause cystitis, prostatitis, pyelonephritis, and dysuria

-E. coli -Klebsiella spp -Proteus spp -Staphylococcus saprophyticus -Enterococcus

Pathogens causing foodborne illnesses, hospitalizations, and deaths

-E. coli (STEC) O:157 -E. coli (STEC) non-O:157 -Enterotoxigenic E. coli (ETEC) -Diarrheal E. coli other than STEC or ETEC

C. trachomatis pathogenesis

-EB survive only a short time outside host cells -RB multiply inside host cells -this produces large cytoplasmic bodies that are used diagnostically -at the end of the division cycle, the RBs re-organize back to EB -48 to 72 hrs later, hundreds of EBs are released from the cell and go on to infect more cells

Differences between ETEC and V. cholerae

-ETEC lack the polar flagella of V. cholerae, so they are less mobile -ETEC also lack mucinase -ETEC does not colonize as intimately as V. cholerae

Lyme disease treatment

-Early or early disseminated phase patients who do not have neurological involvement * Doxycycline (100 mg twice daily) or amoxicillin (500 mg 3 times daily) for 14-21 days -Patients with disseminated disease/arthritis: *same as early treatment, but for 28 days -Patients with clinically evident neurological involvement: *ceftriaxone (2 g once a day intravenous) for 2-4 weeks

Why should pts be tested for TB when considering using Embrel for arthritis?

-Embrel suppresses Th1 immune response in order to treat inflammatory diseases such as arthritis -however, the Th1 response is critical in fighting Tb infection and keeping it under control -this is why pts should be tested for TB before considering using this medication

Enterobacteriaceae associated with diarrheal disease

-Escherichia -Shigella -Salmonella -Yersinia

Diagnosis of Relapsing Fever (RF)

-Examination of blood smears *Darkfield *Light microscopy staining with Wright's or Giemsa -Blood cultures -Serologic tests

M. tuberculosis intracellular survival

-Fc receptors: inhibition of phagosome/lysosome fusion -Mannose: prevents phagosome maturation and acidification -Scavenger: modification of antigen presentation -CR1, CR3, CR4: inhibition of apoptosis, ROI and RNI resistance mechanisms, immune modulation

Suppurative infections caused by S. aureus

-Furuncle/carbuncle -Endocarditis -Impetigo -Wound infections -Osteomyelitis -Septic arthritis -Pneumonia

Streptococcal toxic shock syndrome (STSS)

-GAS strains produce StrepSAgs -toxins spread rapidly and throughout the body, invading multiple organs -soft-tissue necrosis and streptococcal gangrenous myositis can occur w/o trauma of clostridial gas gangrene -may be fatal in healthy persons -more invasive that Staphlyococcus TSS, although exact mechanism is unknown

Vector biology of Tickborne RF

-Genus: Ornithodoros -Nidicolous -Long life span > 20 years when fed regularly -Nocturnal short feeders: 15-90 minutes leading to rapid transmission -Months to years between feeding and still transmit spirochetes

BCG: current practices

-Globally *seed lot system est. 1966 *U.S. and Netherlands are only 2 countries that have never implemented universal BCG vaccination; now Sweden and Czech Republic *UK recommends vaccine for individuals living in high-risk areas or w/high-risk individuals *WHO recommends single dose given at infancy *many countries give 1st dose in infancy and repeated doses throughout childhood -United States *only used in exceptional circumstances

Bacille Calmette-Guerin (BCG) vaccine: the good, the bad, and the ugly

-Good *derived from serial passage of M. bovis in vitro *avirulent in mice, guinea pigs, and humans *administered to 100 million children annually *safe and inexpensive *significant protection against disseminated disease *protection against leprosy -Bad *confers 0-80% protection against pulmonary TB *effacacy wanes over time *route of administration and effacacy of immunizing technique not rigorously evaluated *over 120 genes missing (i.e. RD1) *safety in HIV+ individuals unclear -Ugly *dvlpt of a TB vaccine not a major priority for pharmaceutical companies due to high cost and lengthy follow-up

Neisseria meningitidis (the meningococcus)

-Gram (-) cocci -have a septum between rods (looks like a space) -cause septicemia and meningitis -heavily encapsulated -have hemolysin, which allows them to disseminate into the bloodstream, leading to disseminated intravascular coagulation (DIC) -inflammation of meninges allows phagocytes and blood proteins to enter spinal fluid -can be prevented with vaccination with capsular polysaccharide (except group B strains)

Neisseria gonorrhoeae (the gonococcus)

-Gram (-) cocci -septum between rods (looks like a space) -cause gonhorrhea, which can lead to pelvic inflammatory disease (PID) in women and epididymitis in men -can be carried asymptomatically by both men and women -exhibit phase and antigenic variation -can cause disseminated infections (men and women) -can be treated with antibiotics, though many are resistant

Legionella

-Gram (-), but stains poorly with Gram stain; better to use silver or fluorescent stains -pleomorphic coccobacillus - facultatively intracellular -motile -parasitic free-living amoeba in nature -needs special medium for growth: cysteine, iron, as in BCYE (Buffered charcoal yeast extract) -rapid test: urine antigen test -often associated with lukewarm water sources (showers, air conditioners, source of mist) in biofilms -survive chlorination and temperatures around 50ºC -resistant to penicillins

Treponema denticola

-Gram negative -resident in human oral cavity -predominant in periodontal lesions of adult periodontitis

Helicobacter characteristics

-Gram negative, curved (helical) rod -flagella on 1 pole; multiple, unipolar flagella -20 recognized species, divided into gastric and enterohepatic (nongastric) species -strong organ specificity -H. pylori species most commonly associated with human disease

Staphylococci group characteristics

-Gram positive cell wall structure -tend to form clusters -catalase positive -coagulase positive -Protein A (species specific virulence factor)

Streptococcus pneumoniae

-Gram positive, diplococcus, "bullet" shape -alpha-hemolytic -sensitive to optochin -susceptible to autolysins -aspirated from normal oropharyngeal florea to the lungs, where it produces pneumonia -GBS vaginal colonization during pregnancy leads to infection of fetus in either uterus or during childbirth -pneumolysin as a virulence factor -capsule most important virulence factor, identified by quellung reaction (presence of specific anticapsular antibodies cause capsule to appear swollen)

Campylobacter characteristics

-Gram-negative helical rods (spirals) -polar flagella at 1 or both ends; single, bipolar flagella -strictly microaerophilic (5-10% oxygen) -campy plate: blood agar + sodium bisulfate to reduce redox potential; selective antibiotics to prevent growth of other commensal organisms -thermophilic, with optimal growth at 42ºC (good for colonizing poultry) -25 recognized species

Characteristics of Enterobacteria

-Gram-negative rods (coccobacilli to filamentous) -non spore forming -aerobic, facultative anaerobic -many are part of microbiota -cause intestinal, extraintestinal, and UTIs

Diagnosis of pneumococci

-Gram-positive, lance-shaped diplococci -lower respiratory specimens needed for proper diagnosis -S. pneumoniae grows well overnight on blood agar medium -distinguished from viridans streptococci by susceptibility to optochin or bile solubility

Vacuolating cytotoxin (VacA)

-Helicobacter virulence factor -highly immunogenic: induces pro-inflammatory responses -secreted by H. pylori -forms pores in epithelial cell membrane upon exposure to acidic pH -induces apoptosis upon entry into epithelial cells

Type IV secretion system (T4SS)

-Helicobacter virulence factor -syringe-like structure capable of penetrating gastric epithelial cells -secretes directly into host cell cytoplasm -secretes CagA, peptidoglycan, and other bacterial factors into host cell

Thermally dimorphic fungi (true pathogens) that cause systemic mycoses

-Histoplasma capsulatum -Blastomyces dermatitidis -Coccidiodes immitis -Paracoccidioides brasiliesnis

2 forms of MRSA

-Hospital acquired (HA)MRSA -Community acquired (CA)MRSA--also affects healthy individuals

Borrelia antigenic variation

-In B. hermsii, a New World relapsing fever species, approximately 30 serotypes have been derived from a single cell - serotype of a Borrelia cell depends on its major surface antigen - 30 or so antigens are divided approximately equally between 2 families: 1) Variable Large Proteins (Vlp) ~ 36 kDa 2) Variable Small Proteins (Vsp) ~ 20 kDa -mechanisms: gene recombination (full or partial), rearrangement, hypermutation

Bacteria that cause secretory diarrhea have some features in common

-Include members of the Enterobacteriaceae and Vibrionaceae -Usually transmitted to humans in contaminated food and water -Face formidable defenses of the gastrointestinal tract; adhere to epithelial cells of the GI tract via pili or surface adhesins -May elaborate toxins that reduce sodium absorption and increase chloride secretion by intestinal cells, which leads to watery diarrhea -Treated with parenteral or oral rehydration therapy

Antimycobacterial drug therapies

-Isoniazid (INH) -Rifampin (RFP) -Pyrazinamide (PZA) -Streptomycin (STM) -Ethambutol (EMB)

Salmonella virulence factors

-LPS -fimbriae/pili -T3SS -flagellin

Leptospira virulence factors

-LcpA: surface-exposed protein that binds the human complement regulator C4BP -Leptospiral endostatin-like protein A (LenA) binds human plasminogen; may aid in dissemination -LipL32: a lipoprotein that modulates fibronectin binding

Legionella disease

-Legionnaires' disease *<5% infection rate, sporadic, epidemic *epidemic in late summer and fall; endemic year round *incubation pd: 2-10 days *can cause atypical pneumonia *requires antibiotic therapy *mortality rate: 15-20% (untreated); higher with late diagnosis -Pontiac fever *>90% infection rate, epidemic *can occur throughout the year *incubation pd: 1-2 days *does not cause pneumonia; self-limited *mortality rate: <1%

MOTT: skin and soft tissue

-M. fortuitum and M. chelonae *local abscesses at site of infection *trauma or surgical wounds *corneal infections *endocarditis -M. marinum *fresh and salt water; swimming pools, aquariums *cutaneous granulomas *ulcers -M. ulcerans *cutaneous ulcers *Bairnsdale ulcer (Australia) *Buruli ulcer (Africa)

MOTT: pulmonary disease

-M. kansasii and MAC most common -mostly affects middle-aged men w/chronic lung disease -individuals with predisposing conditions: *previous TB *chronic bronchitis *obstructive lung disease *lung malignancy *AIDS (overwhelming dissemination--MAC)

MOTT (or atypical mycobacteria) characteristics and treatment

-MOTT = mycobacteria other than tuberculosis -habitat: soil, plants, water -transmission by contact with environmental source -highly resistant to drugs; require extensive combination therapy (MAC) -surgical removal of lesions

C. trachomatis clinical diseases

-Males *urethritis *epididymitis *proctitis -Females *cervicitis *acute salpingitis *PID Infants: *inclusion conjunctivitis *chlamydial pneumoniae -Chlamydia is often asymptomatic in males and females (50% each)

TB infection

-Mtb is present -tuberculin skin test = positive -CXR normal -sputum smears and culture = negative -no symptoms -not infectious -not defined as a case of TB

TB disease in the lungs

-Mtb is present -tuberculin skin test = positive -CXR usually reveals lesion -sputum smears and culture = positive -symptoms such as cough, fever, weight loss -often infectious before treatment -defined as a case of TB

Common causes of bacterial meningitis: adolescents and young adults

-N. meningitidis, Streptococcus pneumoniae

Salmonella serotypes determined by 3 antigens

-O or cell wall antigen (somatic) -H antigen (flagellum) -K antigen or Vi antigen (capsule)

T. carateum

-Pinta -South and Central America -disseminated, recurrent, hypopigmented lesions - can lead to scarring and disfigurement -spread by direct contact with lesions

Diagnosis of M. pneumoniae

-Problems: *too small for routine microscopy *Gram stain doesn't work *culture takes too long (2-6 weeks) *high cross reactivity, so serological assays give false positives -Diagnosis based primarily on clinical recognition of syndrome and confirmed by serologic tests or PCR -Historic tests (no longer used): complement fixation test, cold agglutinin (or cryoagglutinin) test

Major virulence factors of S. aureus

-Protein A -Catalase -Coagulase -Leukocidins (notably alpha-toxin, all strains) -Enterotoxins (A-E) -Exfoliative toxins (A,B) -Toxic shock syndrome (TSST-1)

4 species of Shigella

-S. dysenteriae -S. flexneri -S. sonnei -S. boydii

Bartonella

-Similar to rickettsia, but not related -Very small, Gram-negative, facultative intracellular bacteria -Causes cat-scratch fever (B. henselae) and bacillary angiomatosis (mainly in HIV-positive patients; lesions resemble Kaposi's sarcoma) -"trench fever" (B. quintana) -treatment: erythromycin or doxycycline

Lyme Borreliosis progression

-Stage 1: acute illness (weeks) *erythema migrans (EM) rash at site of tick bite *headache, malaise, fatigue, arthralgia, myalgia -Stage 2: dissemination (weeks to months) *facial palsy *cardiac: heart block, pericarditis myocarditis *CNS: meningoencephalitis, cranial neuritis -Stage 3: late chronic form *destructive chronic arthritis (U.S) *acrodermatitis atrophicans (Europe) *neuropathy, cognitive impairment

Common causes of bacterial meningitis: infants and children

-Streptococcus pneumoniae, N. meningitidis, Haemophilus influenzae type B

Common causes of bacterial meningitis: older adults

-Streptococcus pneumoniae, N. meningitidis, Listeria monocytogenes

Pathogenesis of Staphylococcus Toxic Shock Syndrome

-TSST-1 is produced during the course of a staphylococcal infection with systemic disease as a result of absorption of toxin from the local site -TSST-1 is more readily adsorbed across mucosal membranes compared to other StaphSAgs -toxin binds directly with the Vβ portion of the T-cell receptor and the class II major histocompatibility complex (MHC II) receptor -this Vβ stimulation signals the production of cytokines such as interleukin-1 (IL-1) and tumor necrosis factor (TNF)--> cytokine storm

Leptospirosis treatment and prevention

-Treatment *Oral penicillin or doxycycline * Supportive therapy may be necessary (rehydration, dialysis, corticosteriods) -Prevention *No vaccine for humans * Drink sterile water; avoid contaminated areas * Vaccinate domestic animals * Rodent control

Vibrio species frequently associated with human disease

-V. cholera (gastroenteritis) -V. parahaemolyticus (gastroenteritis) -V. vulnificus (bacteremia, wound infection, cellulitis); found in raw shellfish

Vaccination against N. meningitidis

-Vaccine consist of capsular polysaccharide (monovalent, bivalent, and tetravalent formulations) or mixtures of recombinant meningococcal proteins -Type B capsule nonimmunogenic because it contains sialic acid -The 2 quadrivalent (i.e., targeting serogroups A, C, W-135 and Y) meningococcal vaccines available in the US are MCV-4 (a conjugate vaccine, Menactra) and MPSV-4 (a polysaccharide vaccine marketed as Menomune), both produced by Sanofi Pasteur

S. typhi vaccines

-Vi: polysaccharide, intramuscular -Ty21a: live-attenuated, oral -Heat-phenol: killed whole cell, subcutaneous

T. pallidum ssp. pertenue

-Yaws -restricted to primitive areas of tropical South America, Central Africa, and Southeast Asia -spread by direct contact with lesions -destructive lesions of skin and bone

Acid-fast staining methods

-Ziehl-Neelsen (most common) -Kinyoun modification -Auramine rhodamine

Latex agglutination test

-a clinical method to detect certain antigens or antibodies in a variety of bodily fluids such as blood, saliva, urine or cerebrospinal fluid -sample is mixed with latex beads coated with a specific antigen or antibody

Borrelia

-a diverse group of bacteria found in soil, deep marine sediments -commensal in the gut of arthropods -obligate parasites of vertebrates

Superantigens (SAgs)

-a family of secreted proteins that are able to stimulate systemic effects as a result of absorption from the gastrointestinal tract after ingestion or at a site where they are produced in vivo by multiplying bacteria -strongly mitogenic for T cells and do not require proteolytic processing before binding with class II major histocompatibility complex (MHC) molecules on antigen-presenting cells -this bypasses the specificity of antigen processing and results in massive cytokine release (cytokine storm)

Carbuncle

-a lesion that is formed when infection spreads from a furuncle with the development of 1 or more abscesses in adjacent subcutaneous tissues -serious lesions that may result in bloodstream invasion (bacteremia)

Streptolysin O

-a pore-forming cytoxin, lysing leukocytes, tissue cells, and platelets -similar to alpha-toxin in staphlyococcus, this toxin inserts directly into host cell membrane, forming transmembrane pores -antigenic

Panton-Valentine leukocidin (PVL)

-a pore-forming toxin that is active against neutrophils -causes tissue necrosis -found in only a small portion of clinical isolates

Exfoliatin

-a protease which acts on desmosomes important to interkeratinocyte adhesion -produced by a small portion of S. aureus strains -binds to a specific cell membrane ganglioside found only in the stratum granulosum of the keratinized epidermis of the skin -it causes intercellular splitting of the epidermis between the stratum spinosum and stratum granulosum, presumably by disruption of intercellular junctions

Sporotrichosis (Rose Handler's Disease)

-a subcutaneous mycoses caused by Sporothrix schenckii, a dimorphic fungus -chronic infection characterized by nodular lesions of cutaneous or subcutaneous tissues and adjacent lymphatics (lymphocutaneous) -entry gained through trauma--thorn implantation from roses -also known as Rose Handler's Disease

Furuncle or boil

-a superficial skin infection that typically develops in a hair follicle, sebaceous gland, or sweat gland -a prototype for the purulent lesions produced by many other bacteria -ex. of a case: diabetic pt whose blood glucose is not well-controlled with a large swollen area of redness on 1 leg

Pneumolysin

-a transmembrane pore-forming toxin of GBS -not produced directly by pneumoccoccus; rather, it is released on lysis of the organisms augmented by autolysins -can stimulate cytokines and disrupt cilia of human respiratory epithelial cells, facilitating spread into alveoli

Predisposing factors to S. pneumoniae infection

-absence of spleen -HIV -sickle cell anemia -multiple myeloma -Hodgkin's disease

MOTT identification

-acid fast stain -growth temperature (37 vs. 30 degrees Celsius) -rapid growers (3-5 days) vs. slow growers (2-6 weeks) -pigmentation -biochemical activity

Shigellosis

-acquired by ingestion of contaminated food or water -incubation pd: 1-4 days -begins with general symptoms: fever, headache, malaise, anorexia, occasional vomiting -watery diarrhea (sometimes the only symptom) -frank dysentery: inflammatory colitis with 3 classic symptoms: 1) severe cramps, 2) tenesmus, 3) frequent bloody and mucoid stools -most cases resolve spontaneously after 1 week -lethal or life-threatening in malnourished children -rare extraintestinal complications: bacteremia, encephalopathy

Pathogenesis of N. gonorrhoeae

-acquired through sexual contact and establishes infection in urogenital tracts by interacting with non-ciliated epithelial cells ==> results in cell invasion -often leads to inflammation and polymorphonuclear leukocyte (PMN) influx -bacteria engulfed by PMNs are secreted in PMN-rich exudate -TNF from phagocytes and gonococcal products (such as peptidoglycan and LPS) cause toxic damage to ciliated epithelial cells of mucosa

Streptomycin (STM)

-active only against extracellular organisms

Meningococcemia: other signs and symptoms

-acute fever and chills -headache -neck stiffness -lower back and thigh pain -nausea and vomiting -confusion or unconsciousness -epileptic fits (seizures) -unstable vital signs (e.g. very low BP, reduced blood flow, low urine output) -collapse from septic shock

Autoimmune sequelae diseases following strep throat

-acute glomerulonephritis -acute rheumatic fever (ARF)

Guillan-Barré Syndrome

-acute progressive neuropathy -paralysis, pain, muscle weakness, sensory loss -sudden onset -recovery pd can range from a few weeks to years -possibly related to molecular mimicry of lipooligosaccharide (LOS) and human neuronal ganglioside lipids -this molecular mimicry causes an autoimmune response, resulting in axonal degeneration

Pathogenesis of Rickettsia

-adherence to endothelial cells -produce phospholipase to actively enter cells -escape phagocytic vacuole -subvert actin filaments to move into adjacent cells -replicate in cytoplasm and/or nucleus of endothelial cells -leads to cell damage and leakage of blood vessels (vasculitis) -no evidence for toxin production -aerobic; energy parasites (exogenous co-factors and ATP required for survival) -rapidly lose infectivity outside of host cell

UPEC virulence factors

-adhesins (fimibrial: P-pili, Type 1 pili; afimbrial: AFAI, AFAII) -hemolysin (RTX toxin) -cytolytic necrotizing factor (CNF1) -iron siderophores -capsule and serum resistance -TLR agonists -LPS

TB transmission

-aerosolized particles generated by people with active infection -as few as 1-5 bacteria can cause infection -majority of cases arise from re-activation of latent infection -exogenous re-infection w/ a 2nd strain of Mtb can occur *more common in immunocompromised individuals -characteristics influencing transmission: *source *number of bacteria excreted *nature of encounter: duration, closeness of exposure

Epidemiology of UTIs

-affect millions worldwide annually, second only to respiratory infections -most common cause of nosocomial infection in adults -up to 50 % women have UTI at some point in their lives. 25-40% of these will have recurrences -between 2-10% pregnant women are affected -management costs >$2.5 billion in U.S.

Tertiary (late) syphilis

-affects 25-40% of untreated pts -can occur from 3-20 years after initial infection -diffuse, chronic inflammation that is highly destructive; few spirochetes present -granulomatous lesions (gummas) -nomenclature depends on organ affected (ex. neurosyphilis, cardiovascular syphilis)

S. sonnei

-affects industrialized countries and travelers -1 serotype

ETEC diarrheal disease

-affects millions of children >5 years worldwide annually -infection leads to profuse watery diarrhea, which can clinically appear to be cholera -ID: 10^6 - 10^9 organisms -incubation pd: 10 hrs - 3 days -diarrhea lasts 3-5 days

Mannitol salt medium

-agar is DIFFERENTIAL and SELECTIVE -contains a high concentration of salt, making it selective for Gram-positive bacteria since many bacteria cannot tolerate salt -also a differential medium for mannitol-fermenting staphylococci, containing carbohydrate mannitol and the indicator phenol red, a pH indicator for detecting acid produced by mannitol-fermenting staphylococci

alpha-hemolysis

-agar under colony is dark green -caused by hydrogen peroxide produced by the bacterium, oxidizing hemoglobin to green methemoglobin

Acute gastroenteritis

-agent: C. jejuni -bloody diarrhea w/mucus, with 10 or more stools/day -fever -abdominal cramps -colitis -usually self-limiting -loss of fluid due to damage of epithelial integrity and disruption of fluid absorption capabilities of epithelial cells

Typhoid fever

-agent: Salmonella typhi -Vi antigen -bacteria move from liver --> gallbladder -->shed in bile --> shed in intestine -endemic in SE Asia, Africa -human specific disease, with asymptomatic carriers -prevention: sanitation

Syphilis

-agent: T. pallidum -humans are the only natural host -transmitted sexually, congenitally, or by transfusion -transferred primarily in early stages of disease when moist cutaneous or mucosal lesions are present

Cold Agglutinin Disease (CAD)

-agglutination of RBCs occurs at cold (4 degree Celsius) temperature -cold agglutinin test to check for agglutination of RBCs in small vessels

3 types of diseases caused by fungi

-allergies -mycotoxicoses (intoxication) -mycoses (infection)

What is the advantage of dimoprhism?

-allows them to adapt to changes in the environment by changing morphology -in natural habitat (normal temperature), exist as molds (mycelilal phase); hyphae of molds produce spores -these spores enter a warm-bodied human -in the higher T and lower O2 environment of the human; spores bud and germinate into yeast -yeast cells leaving the host enter an environment of decreased temperature and increased O2 -they revert back to sporulating hyphae

Intestinal and luminal protozoa

-amoebas -flagellates (Giardia, Trichomonas) -Coccidia (Toxoplasma, Isopora, Cryptosporidium)

Strep throat

-an acute inflammation of the pharynx and tonsil -includes fever and painful swallowing (sore throat) -caused by S. pyogenes

Chlamydiae psittaci

-an avian pathogen that can be transmitted to humans

C5a peptidase

-an enzyme that degrades complement component C5a -also blocks phagocyte chemotaxis to site of infection

Endocardditis

-an infection of the heart's inner lining, usually involving the valves -case study: Recent onset of fever, petechial lesions, and detection of a new heart murmur in a patient with an intravascular catheter

Streptococcal erysipela

-an infection of the skin and subcutaneous tissues, primarily affecting the dermis -characterized by spreading of erythema and edema with rapidly advancing, well-demarcated edges, pain, and systemic manifestations such as fever and lymphadenopathy -previous history of strep throat is common

Aspergillosis

-an opportunistic mycosis -Aspergillus fumigatus and other species -allergic reactions -aspergilloma -non-invasive aspergillosis -invasive aspergillosis -toxicosis

Candidiasis

-an opportunistic mycosis -Candida albicans and other Candida species -thrush, toe nail infection, diaper rash

Cryptococcosis

-an opportunistic mycosis -Cryptococcus neoformans and other species -CNS infection: cerebromeningeal involvement

Entamoeba histolytica

-anaerobic parasitic protozoan; cause invasive disease in the intestine -can also cause extra-intestinal disease if host ingests cysts and they travel to other organs -use of "Nettipot" (inhalation) to clear sinuses has been linked to widespread infection, as these cysts can travel to the brain; better to clean water and drink it rather than inhale it

Shigella epidemiology

-annually about 150 million cases and 400,000 deaths -in U.S, 500,000 cases annually

Helicobacter treatment

-antibiotics: clarithromycin, metronidazole, tetracycline

Examples of Staphylococcal superantigens

-antigenic variants of the long-known staphylococcal enterotoxins (SEA, SEB, etc) -toxic shock syndrome toxin (TSST-1)

T. pallidum virulence factors: immune evasion

-antigenic variation: TprK gene is responsible for antigenic diversity, depending on the environment of the bacteria, to help it avoid immune detection -outer membrane contains fewer much protein antigens than other gram-negative bacteria

Diagnosis of TB

-approximately 1/3 of individuals exposed to TB show evidence of infection *only 10% infected become ill in their lifetime -tuberculin skin test identifies individuals infected with TB *anergy in some individuals *BCG vaccine used in developing countries can result in positive result during screening -definitive diagnosis *recovering Mtb through culture methods

Epidemiology of tuberculosis

-approximately 2 billion ppl infected worldwide -world's leading cause of death from a single infectious organism -kills more adults annually than AIDS and malaria combined -increasing 10%/year in Africa -10-15 million infected in U.S.

Bartonella pathogenesis

-arthropod vector transmits bacteria to host -colonize the primary niche, which probably involves entry into migratory cells -transport to vascular endothelium, where bacteria persist intracellularly -invade bloodstream; invade RBCs and re-infect - after limited replication inside the red blood cell, they persist in the intraerythrocytic niche, competent for transmission by a bloodsucking arthropod

Means of reproduction for parasites

-asexual or sexual -both may occur with same parasite (ex. malaria, schistosomiasis)

Latent syphilis

-asymptomatic -can relapse into secondary or proceed to tertiary

Congenital syphilis

-at 16 wks gestation, T. pallidum can cross placental barrier -high fatality rate (50%); surviving babies have severe congenital and developmental abnormalities -Hutchinson's triad: notched teeth, interstitial keratitis, eighth-nerve deafness present in 75% untreated children

T. pallidum virulence factors: invasion

-attach to endothelial cells and pass through blood vessel walls -treponemal adhesins (OMPs): located on the pointed ends of the cell; recognize and bind to fibronectin, a glycoprotein on eukaryotic surfaces -also attaches to laminin and collagen, integral components of the basement membrane -hyaluronidase: facilitates perivascular infiltration and placental invasion

Pathogenesis of haemophilus

-attach to respiratory epithelium (pili, OMPs) -invasion between cells (only encapsulated strains are invasive) -in submucosa, the capsule prevents phagocytosis--> causes bacteremia -LOS (lipooligosaccharide, low molecular weight of LPS) contains sialic acid -endotoxin causes systemic effects

Pyelonephritis pathogenesis

-bacteria ascend through the ureter(s) and colonize the kidney, entering into the renal parenchyma -severe inflammation may lead to renal damage

Pathogenesis of wound botulism

-bacteria grow in a deep wound where they produce botulinum toxin that enters the blood (rare)

Pathogenesis of B. pertussis

-bacteria has tropism for ciliated cells -adhere to cells via FHA, pili, and pertactin -TCT and AC destroy ciliated cells (ciliary stasis) -denuded epithelium can't move foreign matter away from lower airways; causes cough -PT absorbed into bloodstream, causing systemic manifestations

Isoniazid (INH)

-bactericidal against intra- and extracellular AFB (acid-fast bacilli) -inexpensive, few side effects -5-7% of TB strains in U.S are resistant (much higher in India and SE Asia)

Rifampin (RFP)

-bactericidal against intra- and extracellular AFB (acid-fast bacilli) -maintains activity against very slowly metabolizing AFB -this sterilizes the sputum the fastest and penetrates well into the CSF

Pyrazinamide (PZA)

-bactericidal only in acidic pH -along with rifamipin and isoniazid, used for initial TB treatment until sensitivity results are known -CSF penetration is best

Ethambutol (EMB)

-bacteriostatic against intra- and extracellular AFB (acid-fast bacilli)

A parasite that infects a host to which it is NOT well adapted may:

-be unable to continue its life cycle -be able to only partially continue its life cycle -only rarely complete the full life cycle

Taenia

-beef and pork tapeworms of humans; infect meat and pork by ingestion of eggs; egg hatches to larva in animals ==> animals are killed but retain parasite, and these larva are ingested by humans -larva grows and matures in small intestine

T. denticola virulence factors: FhbB

-binds Factor H component of complement cascade (serum resistance)

Relative strengths of some toxins

-botulinum toxin (most toxic) -Shiga toxin -tetanus toxin -diphtheria toxin -ricin -T-2 toxin (least toxic)

Pathogenesis of N. meningitidis

-can be acquired through inhalation of aerosol droplets -establishes intimate contact with non-ciliated mucosal epithelial cells of URT, where it may enter the cells briefly before migrating back to apical surface for transmission to a new host -asymptomatic carriage is common in healthy adults -can cross epithelium by transcytosis following damage to the monolayer integrity, or through phagocytosis -In susceptible individuals, once in the bloodstream, can survive, multiply rapidly, and disseminate throughout body and the brain -meningococcal across brain vascular endothelium (or the epithelium of the choroid plexus) may then occur, resulting in infection of the meninges and CSF

Fungal reproduction

-can reproduce asexually or sexually -generally, only asexual forms are important in disease *asexual spores = conidia (infectious propagule) *hyphae grow from these spores in spreading disease

Diagnosis of T. pallidum

-can't be cultivated continuously in vitro; propagated in rabbit testicles -dark field microscopy can be used as a tool if active chancre is present -direct fluorescent antibody staining

Why is it significant that the capsule of S. pneumoniae blocks C3b-mediated opsonization?

-capsule blocks alternate complement pathway -significant because in the absence of specific antibody, the alternative complement pathway is the primary means for signaling phagocytic defense

Coxiella burnetii

-category B bioterrorism agent: very infectious! a single organism can cause infection -obligate intracellular bacteria -infects humans and livestock -biphasic life cycle: small cell variant (SCV), large cell variant (LCV) -causes Q fever *Abrupt symptoms, debilitating headache, onset of atypical pneumonia, cyclical fever *No rash -reservoir: sheep, cattle, goats, other livestock -humans are an "accidental" host -Infection via respiratory route (placenta, dried feces, urine) or via unpasteurized milk, from infected animals -No arthropod vector involved for human cases -Diagnosis: serology, based on signs and symptoms and a high index of clinical suspicion; reference labs only -Vaccine available for at risk population

Pneumocystis jiroveci (carinii)

-causative agent of PCP (pneumocystis carinii pneumonia) *pulmonary "foamy" eosinophilic exudate -a serious opportunistic pulmonary infection with immune suppression -AIDS-defining illness

Mycobacterium tuberculosis

-causative agent of tuberculosis (TB) -spread from person to person by aerosol droplets -slow growing, acid fast bacillus -thick, waxy cell wall -obligate aerobe -survives and replicates in macrophage

Peptic ulcer disease

-causative agent: Helicobacter pylori - no longer a chronic, frequently disabling condition, but a disease that can be cured by a short regimen of antibiotics and acid secretion inhibitors

A 73-year-old man was admitted to the hospital because of breathing difficulties, chest pain, chills, diarrhea and fever of several days' duration. He had been well until 1 week before admission, when he noted the onset of a persistent headache and a productive cough. The patient smoked two packs of cigarettes a day for more than 50 years and drank a six-pack of beer daily; he also had a history of bronchitis. Physical examination revealed an elderly man in severe respiratory distress with a temperature of 39°C, pulse of 120 beats/minutes, respiratory rate of 36 breaths/minutes, and blood pressure of 145/95 mm Hg. Chest radiograph revealed an infiltrate in the middle and lower lobes of the right lung. The white blood cellvcount was 14,000 cells/micL (80% polymorphonuclear neutrophils). Gram stain of the sputum showed neutrophils but no bacteria, and routine bacterial cultures of sputum and blood were negative for organisms. -What is the causative organism? -Disease? -How are Legionella species able to survive phagocytosis by the alveolar macrophages? -What environmental factors are implicated in the spread of Legionella infections? -How can this risk be eliminated or minimized?

-causative agent: L. pneumophila -disease: Legionnaires' disease -can survive phagocytosis once internalized, the bacteria surround themselves in a membrane-bound vacuole that does not fuse with lysosomes that would otherwise degrade the bacteria -in the vacuole, the bacteria can multiply -environmental factors: lukewarm water sources; persist as biofilms -reduce risk: don't smoke (opportunistic infection that takes advantage of destroyed ciliated cells), keep water sources sterilized

A 25 y/o woman with severe nausea, vomiting, and diarrhea that developed 4 hours after eating potato salad and ham sandwiches at a picnic in July comes to the clinic. She recovers completely after bed rest for 2 days and drinking plenty of water. What could be the causative agent? How do you think the symptoms developed so quickly, given a doubling time of about 30 min for this bacterium? What kind of toxin is this?

-causative agent: Staphylococcus aureus -symptoms developed quickly due to release of enterotoxins and superantigen, causing a cytokine storm -cytokine storm is responsible for the nonspecific response, causing emesis and discomfort

Histotoxic infections caused by Clostridium species

-causative agents: C. perfringens, C. septicum, C. novyi, C. sordelli, C. histolyticum (rare), and C. fallx -C. perfringes, type A causes 90-95% gas gangrene cases -these organisms are not highly pathogenic when introduced to normal tissues -however, in presence of pre-existing tissue injury (particularly muscle damage), they can be responsible for rapidly progressive, devastating infections -these infections are characterized by accumulation of gas and extensive muscle and connective tissue destruction (clostridial myonecrosis or gas gangrene)

A 72-year old woman with an indwelling catheter has a UTI and bacteremia. Gram-positive cocci are isolated from the urine. Blood cultures are reactive with group D antiserum, and grow in medium containing detergent and in high salt medium. -What is the causative organism? -What is the reason it can grow in detergent and high salt medium in the lab?

-causative organism: enterococci -can grow in high salt medium because is part of normal GI flora

Pathogenesis of C. perfringens histotoxic infections

-cause bacteremia, myonecrosis, cellulitis, fasciitis, and other soft tissue infections -spores and organisms present in soil, water and sewerage -part of normal flora of GI tract -endogenous spread from GI tract into normally sterile areas -inoculation through breaks in the skin (surgery, trauma) -rapid growth in vivo -production of numerous toxins associated with disease

Lyme Disease

-cause: B. burgdorferi -zoonotic disease -disease-causing bacteria are transmitted to humans by the bite of an Ixodes spp. tick (deer tick)

Leptospirosis

-cause: Leptospira interrogans (multiple serotypes) via invasion of intact mucous membranes or abraded skin -symptoms develop after incubation pd (1-2 weeks) -first described by Adolf Weil (1886) as an "acute infectious disease with enlargement of spleen, jaundice and nephritis" -primary or initial phase is flu-like illness: fever and myalgia, acute onset of headache, chills, abdominal pain, conjuctival suffusion -can progress to more severe disease (Weil's disease) hepatic and renal dysfunction, jaundice, meningitis, vascular collapse, thrombocytopenia, hemorrhage -leptospirosis confined to CNS often mistaken for viral or aseptic meningitis -congenital leptospirosis: flu-like plus diffuse rash -zoonosis worldwide; relatively uncommon in U.S., >50% in Hawaii, probably an underestimate -possible primary cause of death in Native Americans in 1620 (present-day MA) before arrival of Pilgrims

Periodontitis

-cause: T. denticola

Epidemiology of Lyme Disease

-caused by B. burgdorferi in U.S and Europe; by B. garinii and B. afzelli in Europe and Japan -leading vector-borne disease in the U.S.; reported in 49 states -major reservoir hosts are the white-footed mouse and white-tailed deer -transmitted by ticks (Ixodes); nymph stages causes 90% of cases; must feed for 48 hours or more

Acute glomerulonephritis

-caused by GAS -a disease of primarily children -an insidious disease with hypertension, hematuria, proteinuria, and edema due to inflammation of renal glomerulus -may follow either respiratory or cutaneous GAS infection -only nephritogenic strains are involved -usually benign, with spontaneous healing over weeks to months

Acute rheumatic fever (ARF)

-caused by GAS -a prolonged febrile inflammation of connective tissues, which recurs after each subsequent streptococcal pharyngitis -repeated episodes cause permanent scarring of heart valves -follows respiratory, not skin, infection -more common in developing countries, although a resurgence with a different M type occurred in areas of higher socioeconomic status in small outbreaks (1980s)

Streptococcal pharyngitis

-caused by GAS in children -transmission: aerosol droplets -characterized by acute sore throat, malaise, fever, and headache -infection of tonsils, uvula, soft palate--> become swollen, red, and covered with yellow-white exudate -spreading beyond pharynx is rare -treatment within 10 days can prevent ARF

Mycotoxicoses

-caused by accidental or recreational ingestion of toxic substances produced by fungi -some fungi can produce toxins that when ingested, cause a variety of symptoms -mushrooms mostly, plus Aspergillus flavus aflatoxin

Staphylococcal food poisoning

-caused by ingestion of staphylococcal enterotoxin-contaminated food -results in acute vomiting and diarrhea within 1-5 hours -characterized by prostration, but usually no fever -rapid recovery

Pathogenesis of glomerulonephritis after strep throat

-caused by reaction to immune complexes (type 3 hypersensitivity) -immune complexes are deposited in wall of blood vessel -these complexes activate complement and neutrophil inflammatory response -enzymes released from neutrophils cause damage to endothelial cells of basement membrane

Salmonellosis

-caused from food poisoning due to Salmonella -12-72 hrs: nausea, vomiting, fever, diarrhea, abdominal cramps -4-7 days: illness ranges from mild to severe; most people recover without need for treatment -most Salmonella are not resistant to stomach acids -severe cases usually develop in infants, elderly, and immunocompromised individuals, who may require antibiotics

M. leprae

-causes leprosy -replicates within skin histiocytes, endothelial cells, and Schwann cells -prefers 30 degrees Celsius, doubling time = 14 days -mode of transmission unclear -reservoir: humans (major source), armadillos

H. ducreyi diseases

-chancroid *painful genital ulcer with satellite lesions *mainly in Africa, Asia, and S. America *major contributor to spread of AIDS in Africa (chancroid is a co-factor for HIV acquisition and transmission) -treatment: azithromycin, ceftriaxone

Bullous impetigo

-characterized by blisters containing many staphylococci in the superficial layers of the skin -a localized form of staphylococcal scalded skin syndrome

Hutchinson's triad

-characterized by notched teeth, interstitial keratitis, eighth-nerve deafness -present in 75% untreated children with congenital syphilis

Acquired response to Mtb

-characterized by production of IL-12, TFN-a, and IFN-gamma, and granuloma formation ("walling off" mechanism") -Th1 response is critical -mutations in Th1 cytokines/receptor can lead to severe mycobacterial disease -no Th1 to Th2 shift -antibody response not sufficient b/c bacteria is intracellular

Antibiotic susceptibility test

-checks which strains are antibiotic-resistant

Pneumonia pathogenesis

-choline-binding proteins help bacteria attach to cell wall and carbohydrates on the surface of host epithelial cells -aided by exposure of additional receptors by neuraminidase digestion, viral infection, or pneumolysin-stimulated cytokine activation -weakens host immune defenses, allowing bacteria to multiply in alveoli -in late stages, macrophages dominate and resolve lesions, which does not cause structural damage to the lung

Leprosy

-chronic infectious disease caused by M. leprae -mode of transmission unclear -requires prolonged contact -children more susceptible -males infected more than females -hypothesis: skin-skin contact, nasal discharge, and penetrating wounds (arthropod bites) -2 major forms of the disease: tuberculoid leprosy and lepromotous leprosy -cases occur worldwide, mostly tropical areas of Asia and Africa -in U.S., most cases in LA, TX, CA, HI, and mostly in immigrants

Mycoses Diagnosis

-clinical manifestations -microscopic findings (lab diagnosis based on asexual reproductive structures) -direct examination of specimens *KOH prep of lesion or scales from skin lesion, etc. *India ink of CSF in suspected cryptococcal meningitis *Giemsa stain, calcoflour -histology *Periodic Acid Schiff (PAS) *Gomori's methenamine silver nitrate (GMS) -lab cultures *special media, long incubation, determine yeast --> mold transition for dimophic fungus *traditional media, commercial kits -serology *identify patient's antibodies *use commercial antibodies to detect circulating antigen; latex agglutination -other assessments: radiology, clinical chemistry -contemporary lab tests: PCR to amplify fungal DNA

Tetanus manifestations

-clinical manifestations stem from a potent neurotoxin (tetanospasmin) elaborated when spores of C. tetani germinate after gaining access to wounds -disease develops in the setting of penetrating trauma, chronic skin ulcers, infections about the umbilical stump in the newborn (neonatal tetanus), obstetrical procedures (post abortal tetanus), and infected injection sites in narcotics addicts -incubation pd: 3-21 days, avg is 8 days -generally, the further the site of infection from the CNS, the longer the incubation pd -the shorter the incubation pd, the higher the chance of death -neonatal tetanus: symptoms usually appear from 4 to 14 days after birth, averaging about 7 days

S. aureus surface binding proteins

-clumping factor (Clf): binds to fibronogen -fibronectin-binding proteins (FnBPs) -protein A: species specific, binds to Fc portion of IgG molecules

S. lugdunensis

-coagulase-negative Staphylococcus -frequently associated with endocarditis

UTI pathogenesis

-colonize vaginal introitus, periurethral skin, distal urethra, and bladder -attach and resist flushing action of urine -bladder and kidney cells can internalize E. coli -released cytokines induce inflammation -different bacterial strains vary in their ability to induce inflammation

C. jejuni

-colonizes lower intestinal tract (ileum, jejunum, colon) -causes acute gastroenteritis

S. saprophyticus (novobiocin-R)

-common in UTIs -usual habitat is the GI tract and female GU -novobiocin resistance is often used to separate S. saprophyticus from other urinary isolates -second most common cause of UTIs in young women (after E. coli)

C5a

-complement component -main factor that attracts phagocytes to sites of complement deposition

Borrelia burgdorferi immune resistance mechanisms

-complement suppression -stimulation of anti-inflammatory cytokines -gene conversion; antigenic and phase variation -extracellular adhesion, invasion (cystitis, immunological susceptible sites)

beta-hemolysis

-complete hemolysis of red cells in the media around and under the colonies: the area appears lightened (yellow) and transparent

Mold

-composed of long, multicellular filaments (hyphae) -a cluster of hyphae is called a mycellium

Viridan streptococci

-comprises all alpha-hemolytic streptococci that remain after the criteria for defining pyrogenic streptococci and pneumococci have been applied -reside in flora of oral and nasopharyngeal cavities -basic bacteriologic features of streptococci but lack specific antigens, toxins, and VFs of the other groups -ex. subacute bacterial endocarditis, which can be fatal if untreated -takes advantage of weakened immunity or when protected from host defenses -optochin-resistant -insensitive to bile, helping them survive in the GI tract

Tuskegee Study

-conducted in Tuskegee, Alabama (1932-1972) -sample included 399 impoverished African Americans with syphilis -pts were never informed of their disease nor given treatment -1940s: penicillin was validated as an effective cure for syphilis -unethical study leaked to press in 1972 -led to est. of Office for Human Research Protections (OHRP) as well as requirements for Institutional Review Board (IRB) for approval of studies involving human subjects

Mycoses Prevention

-consider fungal etiology in patients with presumed bacterial or viral infections who are not improving with treatment -be familiar with fungal diseases that are common in your geographic area, and consider a patient's travel history to known endemic areas, even if the time spent there was limited -request that specific fungal diagnostic tests and cultures be performed. -patient education (e.g. Histo= Cave disease; Cocci= pregnancy)

Widal test for typhoid fever

-considered positive if the O-antigen titer is more than 1:160 during an active infection, or if the H-antigen is more than 1:160 from past infection or immunized individuals

Various ways of transmission for parasites

-contact (usually involving some form of active invasion by parasite) -ingestion -vertebrate and arthropod vectors -congenital transmission

Fungal cell membrane

-contains ergosterol (instead of cholesterol in mammalian cells) *some anti-mycotics are specific for ergosterol

23-valent Pneumococcal polysaccharide vaccine (PPV)

-contains purified polysaccharide extracted from the 23 serotypes of S. pneumoniae most commonly isolated from invasive disease -shares T-cell independent characteristics of other polysaccharide immunogens -recommended for children 2 years and older

M. tuberculosis virulence factors

-cord factor (trehalose dimycolate) *mycolic acid in cell wall (Antigen85 complex) *highly antigenic *signals through C-type lectin (Mincle) -other glycolipids in cell wall -ROI/RNI survival genes (sodC, katG, ahpC, noxR1) -Esx secretion systems *Esx-1 secretes ESAT-6 and cfp10: immunomodulation

M. pneumoniae virulence factors

-cytadherence (cilia adherence) -produce H2O2 and other radicals -CARDS (Community acquired respiratory distress syndrome) toxin -antigenic variation of lipoproteins in membrane -stimulates antibody response -circulation of auto-antibodies (glycolipids) may be involved in pulmonary and extra-pulmonary manifestations of infection -formation of cold hemagglutinins (agglutinate RBCs at low temperature due to immune antibody response; body does not "see" these hemagglutinins at normal body T)

Tuberculin skin test

-delayed type hypersensitivity reaction -PPD is the antigen; measure size of induration 48-72 hrs later -positive result indicates prior infection with Mtb *caveat: BCG vaccine can result in a false positive

Serologic diagnosis of Treponema

-detect specific Treponemal antibody: FTA-ABS, TB-PA (MHA-TP), and EIAs -used to confirm positive Treponema test -usually positive for life of patient

Coagulase test

-determine presence of coagulase -rabbit serum + Staphyloccocus = fibrin forms due to clumping, coagulase-positive -rabbit serum + bacteria = no fibrin, coagulase-negative

Catalase test

-differentiates between Staphyloccocus and Streptococcus -apply 3% H2O2 -apply colones -bubbling, producing reaction: catalase-positive = Staphylococcus -no bubbling, liquid: catalase-negative = Streptococcus

B. quintana

-disease: "trench fever" *•several episodes of fever, lasting about 5 days ("quintana") *endocarditis, bacillary angiomatosis, and chronic lymphadenopathy *now mainly in homeless population *originally described in military personnel during WWI -reservoir: humans; vector: body louse -infection through contaminated feces or human body louse

R. typhii

-disease: endemic (or murine) typhus -clinical symptoms: maculopapular rash on trunk milder than epidemic typhus -common in TX and S. Ca -reservoir: rodents -vector: flea -vector transmission: defecation

A premature male infant in the pediatric ICU begins to exhibit repetitive coughing, which progresses to his turning red, choking, and gasping for breath. The episodes are sometimes followed by vomiting. On 10th day, he suffers apnea and now requires ventilatory assistance. Pulse and respiratory rate are highly elevated. The chest radiograph is clear. No evidence of tracheal abnormalities. WBC count is abnormally high with lymphocytosis. -What is the disease called? -Causative agent? -Where did he catch the "bug"?

-disease: pertussis ("whooping cough") -agent: Bordetella pertussis -possibly caught "bug" from older family members; even if they were vaccinated, booster shots are needed because immunity wanes over time

R. akari

-disease: rickettsialpox -vector: mites -eschar at the site of the bite and a vesicular rash

Clostridium tetani

-disease: tetanus -tetanus is an acute, often fatal bacterial disease -symptoms arise from tetanospasmin toxin, which is activated once bacterial spores germinate after gaining access through wounds

Mycoplasma genitalium

-disease: urethritis -site: GU -transmitted by sexual contact

Ureaplasma urealyticum

-disease: urethritis; PID; postpartum fever -site: GU; respiratory tract and CNS of newborns -transmitted by sexual contact

Mycoplasma hominis

-diseases: PID; postpartum fever; pyelonephritis -site: GU; respiratory tract and CNS of newborns -transmitted by sexual contact

Clostridium difficile (C. diff)

-diseases: antibiotic-associated diarrhea (ADD), pseudomembranous colitis -spore-forming, G(+), anaerobic bacillus -produces 2 exotoxins: toxin A and toxin B

Clostridium botulinum

-diseases: foodborne, wound, and infant botulism

Clostridium perfringens

-diseases: gas gangrene, food poisoning, soft tissue infections

Mycoplasma pneumoniae

-diseases: primary "atypical" bronchopneumonia ("walking pneumonia"); mild hemolytic anemia (cold hemagglutinin IgM); tracheobronchitis; pharyngitis; Guillain-Barre syndrome (GBS)? -site: respiratory tract -transferred by aerosol droplets

Secondary syphilis

-dissemination in bloodstream and lymphatics -flu-like symptoms and lymphadenopathy -->followed by widespread mucocutaneous rash on the palms and soles of feet -rash disappears within 2-4 weeks -can cure spontaneously

Enterococci

-distinguished by presence in intestinal tract -ability to grow in presence of high concentrations of bile salts and sodium chloride -many produce nonhemolytic or alpha-hemolytic colonies that are larger than those of most streptococci -occur almost exclusively in hospitalized pts w/trauma, abdominal surgery, or compromised defenses -many are resilient and form biofilms -highly resistant to many commonly used antibiotics -no potent toxins or defined virulence factors -ex. Enterococcus faecalis, E. faecium

Coagulase-negative Staphylococci (CoNS)

-do not produce coagulase, alpha-toxin, exfoliatin, or any of the StaphSAg toxins -have surface adhesins and the ability to produce extracellular polysaccharide biofilms -common human infections: S. epidermidis, S. saprophyticus

Kinyoun modification

-does not require heat -carbol fuchsin and malachite green

TyphiDot test for thypoid fever

-dot ELISA kit that detects IgM and IgG antibodies against an outer membrane porin of S. typhi -IgM shows a more recent infection -IgG shows a more remote infection

Menstruation-associated Toxic Shock Syndrome (TSS)

-during menstruation, relatively high protein level and pH in vagina favor growth of S. aureus -combination with composition of high-absorbency tampons provide pH and ionic conditions that enhance staphylococci growth and TSST-1 production -produces superantigen-mediated cytokine release --> systemic shock -characterized by high fever, vomiting, diarrhea, sore throat, and muscle pain -shock, renal, and hepatic injury may follow

UTI symptoms

-dysuria -increased urine frequency -hematuria -fever -nausea/vomiting (pyelonephritis) -flank pain (pyelonephritis)

History of Lyme Disease

-early 20th century: European physicians observed patients erythema migrans (EM), associated this rash with the bite of ticks, and postulated that it was caused by a tick-borne bacterium -1970: Physicians observe clusters of children with arthritis in and around Lyme, Connecticut -1982: Spirochetes identified in the midgut of the adult deer tick, Ixodes dammini and given the name Borrelia burgdorferi -1984: Conclusive evidence that B. burgdorferi caused Lyme disease came when spirochetes were cultured from patients with the Lyme (EM) rash

Diagnosis, treatment, and prevention: RMSF and epidemic typhus

-early diagnosis based on clinical suspicion -reference labs only (PCR, IFA) -treatment: antibiotic therapy within 1st week: doxycycline, chloramphenicol as an alternative (RMSF and typhus) -prevention: avoid tick-infested areas; use insect repellents and check for ticks (RMSF) -epidemic typhus can be controlled through improvement in living conditions, e.g. reduction of lice population -No vaccines available for RMSF, available for epidemic typhus (only high-risk populations) -Appropriate antibiotic therapy should be initiated immediately when there is suspicion of Rocky Mountain spotted fever or typhus, rather than waiting for laboratory confirmation!

Syphilis treatment

-early stages: long-acting benzathine penicillin -congenital and secondary: penicillin G -tertiary: treatment is largely ineffective

T. pallidum ssp. endemecium

-endemic syphilis or "bejel" -common in less-developed tropical and subtropical areas of Africa, Asia, and Australia -spread by contaminated utensils -manifests as oral papules; gummas of skin, bone, and nasopharynx

Tickborne (Ornithodoros) Relasing Fever

-endemic; Borrelia sp. (at least 10) -B. hermsii (most human illness), B. parkeri, B. turicatae -can be spread from rodents, and serve as a reservoir for the infection, via a tick vector -found primarily in Africa, Spain, Saudi Arabia, Asia, and certain areas in the Western U.S. and Canada -Borrelia duttoni is responsible for the relapsing fever found in Central, East and southern Africa

Cholera toxin pathogenesis

-enters cell, routed in retrograde path from Golgi to ER -transported into cytosol via ER-associated degradation (ERAD) pathway by pretending to be a misfolded protein -alpha subunit of toxin ribosylates Gsα (G-protein of adenylate cyclase stimulator), leading to activation of adenylate cyclase and production of cAMP -cAMP production activates protein kinase A (PKA) -PKA phosphorylates CFTR, opening channel and leading to Cl- efflux

Neuraminidase

-enzyme produced by GBS -cleaves sialic acid in host mucin, glycolipids, and glycoproteins

Lousborne (Pediculus humanus) Relapsing Fever (RF)

-epidemic; B. recurrentis -occurs amid poor living conditions, famine in the developing world -currently prevalent in Ethiopia and Sudan -mortality rate is 1% with treatment; 30-70% without treatment

Rocky Mountain Spotted Fever (RMSF)

-etiologic agent: R. rickettsii -common in N., S. and Central America -vector and reservoir: ticks *transovarian transmission *other reservoirs: rodents, dogs -onset of symptoms: about 7 days after tick bite -usually flu-like symptoms -rash may develop up to 3 days or later *rash spreads from extremities to trunk *involves palms and soles (centripetally) -if rash does not develop, diagnosis is delayed and complications arise

Brill-Zinsser disease

-etiological agent: R. prowazekii -less severe form of typhus that occurs years after initial infection -symptoms and rash similar to typhus

Epidemic typhus

-etiological agent: R. prowazekii -vector: human body louse; reservoir: humans -humans are principal reservoir -spread person to person by louse vector -Recrudescent disease can develop years after initial infection (Brill-Zinsser disease) -onset of symptoms occurs about 8 days after louse bite -usually flu-like symptoms -rash develops in only about 40% of pts *begins on trunk and spreads peripherally (centrifugally) *does not involve palms or soles of feet -mortality rate up to 66% in some epidemics -clinically similar to RMSF except for rash

Characteristics of fungi

-eukaryotic -have nucleus (can be multi-nucleated), chromosomes (haploid, diploid, several types), a nuclear membrane, and cytoplasmic organelles -about 1.5 million species; however, only about 300 species are medically relevant -ability to cause disease in humans is likely an accidental phenomenon: for most species, infection of a host is not necessary for maintenance or dissemination of the species

Streptococci superantigens (StrepSAgs)

-exotoxins that have multiple effects, including fever, rash (scarlet fever), T-cell proliferation, B-lymphocyte suppression, and heightened sensitivity to endotoxin due to cytokine storm

C. diff infection risk factors

-exposure to organism -prolonged hospital exposure -old age -comorbidities (inflammatory bowel disease, gastrointestinal surgery, cancer, chemotherapy treatment, and organ transplant) -immunosuppressive pts -illness severity -malnutrition -male gender -recent or frequent use of broad-spectrum antibiotics -use of proton pump inhibitors may also be a risk factor

Fungal allergies

-exposure to the respiratory tract by many saprophytic (live on dead animals or plants) fungi can induce IgE responses and stimulate allergic rxns upon re-exposure -neither growth nor viability of the fungal cells are necessary for induction of allergic responses -molds (esp. Aspergillus species), are responsible for most fungal-related allergies (mold counts)

Streptokinase

-extracellular product of many GAS strains -causes lysis of fibrin clots through conversion of plasminogen in normal plasma into plasmin

protein F and LTA

-fibronectin-binding protein and lipoteichoic acid in GAS -exposed on streptococcal surface and play a role in pathogenesis

Controlled expression (phase variation) of Type 1 fimbriae expression in E. coli

-fimS contains promoter for genes encoding structural fimbriae subunits (including fimA and fimH) -is flanked by 2 inverted repeat sequences: IRL, IRR -->IRL is inverted version of IRR -ON-to-OFF inversion of switch mediated by recombinases FimB and FimE -OFF-to-ON inversion mediated by FimB

Helicobacter virulence factors

-flagella: motility: chemotaxis toward higher pH environment of stomach lining -acid resistance: urease converts urea --> ammonia (raises pH) + CO2; ammonia is cytotoxic to epithelial cells -VacA (vacuolating cytotoxin) -Type IV secretion system (T4SS)

Campylobacter virulence factors: invasion of epithelial cells

-flagellar export system: secretes/exports proteins that aid invasion -Campylobacter invasion antigen (Cia), specifically CiaB, and flagellin protein FlaC required for host cell invasion, although their specific roles are unknown

Campylobacter virulence factors: motility

-flagellum: chemotaxis toward mucin and other mucosal components -composed of flagellin components FlaA and FlaB -CheY: response regulator needed for flagellar rotation; under/over expression results in level of virulence -corkscrew morphology aids in cell penetration

Campylobacteriosis treatment

-fluid and electrolyte therapy -antibiotics: erythromycin and azithromycin

Auaramine rhodamine

-fluorescent stain

Alflatoxins B1

-fungal toxin -produced by certain molds, such as Aspergillus flavus -potent natural carcinogen that can also cause acute liver failure

Psilocybin and Psilocin

-fungal toxins that cause hallucinations -LSD drug is a synthetic analog of these toxins

Genetic factors that may play a role in acute rheumatic fever (ARF)

-gene for an alloantigen found on the surface of B lymphocytes occurs 4-5 times more frequently in ARF patients than general population -suggests a genetic predisposition to hypersensitivity to streptococcal products

Phase variation of fimbrial adhesins

-genetic expression of P-pili and Type 1 pili can turn them on/off, depending on environment -formation of "on" complex depends on inversion (type 1 pili) or differential methylation (P-pili) of specific DNA sequences

Significance of Relapsing Fever Borreliosis

-geographic distribution of RF spirochetes largely over-laps that of malaria; reports indicate that RF is misdiagnosed as malaria, so the true morbidity of this disease is likely underrepresented -morbidity and mortality may be increased by co- infections of the spirochetes with trypanosomes or malaria parasites -persistent nature of the diseasedue to the neurotropism of the spirochetes -neonatal pathology and death associated with infections

Ascaris

-giant roundworms infecting humans -penetrates duodenum and enters bloodstream -in about 3 weeks, llarvae pass through bloodstream, through liver and heart, and are coughed up by respiratory system and sent down to small intestine, where it matures

Salmonella spp characteristics

-gram negative bacilli -none-spore forming -do not ferment lactose -mobile (peritrichous flagella) -facultative anaerobes -produce H2S+

Streptococci

-gram-positive -catalase-negative -smaller, usually arranged in chains of oval cells -medically important streptococci are not acid-fast, not spore-forming, and nonmotile

Common causes of bacterial meningitis: newborns

-group B streptococcus, E. coli, Listeria monocytogenes

Pathobiology and virulence factors of fungal diseases

-have multiple weak virulence factors -adherence to host tissue is critical in some species -resistance to phagocytosis -transformation to alternate forms (yeast, hyphae, spherule) in the host -production of destructive enzymes -capsule production (ex. Cryptococcus neoformans) -immunomodulating factors

What are some reasons a parasite is typically considered to have a complex life cycle?

-helminths, in particular, have multiple stages -different maturation stages may be associated with different hosts -each stage of a parasite's life cycle may be associated with a unique pathogenicity -the complexity of the life cycle provides multiple targets for control, prevention, immunity, and treatment

Descending UTI

-hematogenous infection -bacteremia occurs first, then colonization of kidney

Streptococci can be identified by...

-hemolysis pattern on blood agar -Lancefield carbohydrate group -biochemical activity (species)

Anisakiasis

-herring worm disease, caused by nematodes by ingesting raw or undercooked seafood or fish

Typhoid fever signs and symptoms

-high grade fever (104F) -malaise -abdominal pain/cramps -swollen abdomen -constipation -rash/rose spots -deliria or "typhoid state" induced by fever -complications: intestinal bleeding or perforations, myocarditis, endocarditis, pancreatitis, meningitis, pneumonia

Leptospira characteristics

-highly coiled, thin spirochetes with bent or hooked ends (6-20 µm long) -highly motile -can be visualized by darkfield microscopy -microaerophilic and grow best at 30oC -can be grown in enriched artificial medium (so can be cultured from clinical specimens) -generation time is slow (6-16 hours)

Opportunistic fungal pathogens

-host defenses must be impaired for them to grow -have no significant or defined virulence traits

N. gonorrhoeae virulence factors

-hypervariability of surface proteins and pili -blocks antibodies -intracellular resistance -resistant to multiple antibiotics -mucosal portal of entry -for these reasons, no vaccine available

Factors that increase risk of TB

-immigration: foreign-born persons account for 59% of the new cases in the U.S. -crowded conditions: homeless shelters, prisons -emergence of HIV -decline in public health infrastructure: in 1972, federal funding for TB control ended

Complex parasitic interactions and their effects on immunity

-immunity after infection is typically partial (or absent) rather than complete (ex. malaria) -most infected hosts will have a response which may limit parasite population, but does not completely eradicate it nor does the immune response cause pathology (well-adapted parasites, such as strongyloides) -many have complex mechanisms of immune evasion (ex. schistosoma) -incidental hosts often have a more exuberant immune response to a parasite (ex. larva migrans) -some hosts may prevent/limit pathology due to the effects of the parasite (ex. toxoplasma) -some parasites manifest as a pathology itself (ex. schistosoma)

Impetigo

-in older children, produced by exfoliative toxins from S. aurueus, forming blister-like lesions -case study: child with honey-colored or clear crusts over ruptured pustules (usually bullous lesions) on the face; intense itching

Chlyamydiae

-include genital, ocular, and respiratory pathogens -cause damage by evoking both cellular and humoral immune response -can be treated with antibiotics that are able to enter host cells

Relapsing Fever (RF)

-incubation pd: 2-15 days -fever, headache, myalgia lasting 3-7 days (spirochetemia) -afebrile period lasting 1 week -development of new antigenic types -cycle repeats: each cycle is characterized by emergence of a new variable surface protein -single relapse for epidemic and up to 10 relapses in tickborne -myocarditis most common cause of death; hepatic necrosis and cerebral hemorrhage *<5% mortality with endemic RF *Up to 40% mortality in epidemic RF

Who's at risk for getting TB?

-individuals residing with infected pt -HIV/AIDS pts -poverty-stricken, homeless -IV drug users -nursing home residents (age, malnourishment) -healthcare professional employed in high-risk areas -prisoners

Cutaneous fungal mycoses (or dermatophytoses)

-infection of keratinized tissues, deeper in the epidermis and its integuments (skin, hair) -this elicits some degree of host response -caused by a group of fungi known as dermatophytes -ex. tinea infections, ringworm

Puerperal fever

-infection of the endometrium by GAS at or near delivery that is life-threatening -"childbed fever" (19th century) -rare, but this form is most likely to produce a rapidly progressive infection

Scarlet fever

-infection with strains that elaborate any of the StrepSAgs may superimpose the signs of scarlet fever on pt with pharyngitis -caused by secreted erythrogenic toxin (ET), a superantigen -strep throat with a characteristic "sandpaper" red rash -the buccal mucosa, temples, and cheeks are deep read -pale area around mouth and nose (circumoral pallor) -for unknown reasons, less severe and common now than in early 20th centruy

Immunity and Treatment of Shigella

-infections confer short-lived immunity only to the same serogroup -no licensed vaccine available -palliative treatment, no antispasmodics -treatment usually given to reduce shedding b/c disease is self-limiting -may also give ceftriaxone or azithromycin

Subcutaneous mycoses

-infections in the dermis, subcutaneous tissues, muscle, and fascia -infections generally resulting from traumatic implantation of fungi into the skin -usually localized, but can spread *usually the fungus is recognized as foreign by the immune system ==> induces inflammatory response and tissue damage -ex. sporotrichosis (caused by Sporothrix schenckii, a dimorphic fungus)

Superficial fungal mycoses

-infections of the hair, nails, and startum corneum -infection of dead tissue does not elicit host response -ex. pityriasis (tinea) versicolor (caused by Malasezzia furfur)

Systemic mycoses

-infections that spread from the original site of infection via the bloodstream and/or lymphatic system to other tissues in the body -many acquired via inhalation; thus, can begin as a primary pulmonary disease *true pathogens (dimorphic): Histoplasma capsulatum, Blastomyces dermatitidis, Coccidioides immitis, Paracoccidioides brasiliensis *opportunistic pathogens: Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Pneumocystis, Zygomycetes

Mycoses

-infections with fungi; can be: *superficial *cutaneous and subcutaneous *systemic -caused by both "true" and "opportunistic" pathogens -account for 10% of nosocomial infections--an emerging medical concern

H. pylori

-infects 50% of world's population -no animal reservoir -fecal-oral transmission -most become colonized as children and remain colonized for life

Salmonella pathogenesis

-ingested bacteria travel to small intestine via macrophages, adhere to lining, and invade epithelial cells -severe cases: bacteria break through lining into bloodstream (septicemia)

Vibrio cholerae pathogenesis

-ingested in large numbers -sensitive to gastric acidity -colonization of small intestine aided by motility, mucinase, receptors -toxin production leads to increase in cAMP -causes massive loss of fluid and electrolytes

Pathogenesis of infant botulism

-ingested spores germinate and colonize the colon of infants whose resident flora is not fully developed -symptoms: infants are lethargic, feed poorly, constipated, have a weak cry, and have poor muscle tone -often associated with consumption of raw honey -most common form of botulism in the U.S.

Pathogenesis of M. tuberculosis

-inhalation of bacteria -bacteria reach lungs and enter macrophages -reproduce inside macrophages -lesions form (granuloma): 2 possible pathways: *macrophages activate, immune response, keeps infection under control (latent stage), lesion calcifies OR *lack of immune response, lesion liquifies, bacteria are coughed up in sputum, spread though blood and to organs, resulting in death

Case study: Wound infection: Young man with fever and redness, pus and swelling at the site of recent surgery -How did the organism get to the site? -How does it survive host immune defenses and how does it cause damage?

-invasive bacteria reach epithelial site through skin breach, have many surface adhesive factors -produce collagenase and hyaluronidase to break down tissues and invade deeper -produces coagulase-->clotting-->released into bloodstream -avoid immune defenses -Protein A in S. aureus inhibits phagocytosis and avoids opsonization -purulent (produces pus)

H. influenzae diseases

-invasive disease *caused by encapsulated strains (mainly Hib) *meningitis, acute epiglottitis, cellulitis, arthritis -localized disease *caused by mostly non-encapsulated strains *otis media, sinusitis, chronic bronchitis -treatment: ampicillin, 3rd generation cephalosporins -vaccination

Blood and tissue protozoa

-kinetoplastids *Trypanosoma (sleeping sickness, Chaga's disease) *Leishmania (Old and New world, visceral vs. cutaneous vs. mucocutaneous) -apicomplexa *Plasmodium (malaria) *Babesia

Clostridia characteristics

-large, pleomorphic, Gram (+), rod-shaped -all species form spores -most species have peritrichous flagella and are motile -some (C. perfringens) are encapsulated -all are anaerobic, but sensitivity to oxygen varies -spores are heat-resistant and disinfectant-resistant; germinate only under strongly reducing conditions -natural habitat: soil, intestine of humans and animals

Primary syphilis

-lesion at portal of entry: painless, but highly infectious chancre with raised borders -regional lymphadenopathy -response occurs 3 weeks after infection -lesions generally heal spontaneously within 2 months

Periplasmic flagella of spirochetes

-lie between outer membrane and peptidoglycan layer (in periplasmic space) -attached subterminally at each pole of the cell and extend along the body of the organism -allow bacteria to move in corkscrew motion; especially suited for viscous environments

Opisthorchis viverrini

-liver fluke; trematode parasite -infects humans through raw or undercooked fish -infects human intestine and gallbladder

Hyphae

-long, multicellular filaments found in mold -a cluster of hyphae ==> mycellium -hyphae can be septate (with partitions) or aseptate (coenocytic = no partitions)

Characteristics of spirochetes

-long, thin, corkscrew structure -Gram negative -periplasmic flagella -slow generation time -microaerophilic -have complex nutritional requirements -cause systemic infections (multiple organ tropism) -persist in otherwise healthy people -no human vaccines available

S. flexneri

-major cause of shigellosis in children in developing countries -15 serotypes

Capsule of S. pneumoniae

-major determinant of virulence -interferes with effective deposition of complement (C3b) on the organism's surface, blocking opsonization and phagocytosis -choline-binding proteins also bind serum factor H, blocking phagocytosis

T. denticola virulence factors: Msp

-major outer sheath proteins (Msp): cell attachment (fibronectin, laminin) and porin function that is toxic to host cells; homologous to tpr genes of T. pallidum

Fungal cell wall

-mannoprotein (peptidomannan) is the major antigenic component recognized by host antibodies -various glucans are poorly immunogenic -chitin is composed of B-1,4-linked N-acetyl-D-glucosamine units *some dyes are chitin-specific for staining

M protein

-many different immunotypes, which are the basis of a subtyping system for GAS; virulent -fibrillar coiled molecule with structural homology to myosin -on peptidoglycan wall and most available to immune surveillance -binds serum H, leading to diminished availability of alternate-pathway generated complement component C3b for deposition on the streptococcal surface -blocks complement deposition -anti-phagocytic

Chlamydiae pneumoniae

-may be an almost universal pathogen in humans

Other pyrogenic streptococci

-may resemble those caused by group A or B -a few foodborne outbreaks linked to group C and G -none of the non-group A pyrogenic streptococci associated with poststreptococcal sequelae

Infections associated with N. meningitidis

-meningitis -septicemia -PID -urethritis -arthritis

Fungi as infectious agents

-molds and yeasts are widely distributed in air, dust, fomites, and normal flora -humans are relatively resistant -fungal virulence is multi-factorial -only about 300 species have been linked to disease in humans and animals -some adaptations for survival and growth in humans (not all applicable to all pathogenic/opportunistic fungi) *hyphal-to-yeast switch at 37 deg. C. (thermal dimorphism) *ability to survive both at ambient temperature and 37 deg. C. *ability to thrive both as commensals and as pathogens

Pathogenesis of acute rheumatic fever (ARF) after strep throat

-molecular mimicry (type 2 hypersensitivity) -streptococcal cell wall stimulates antibody production -some antibodies cross-react with heart tissue, causing heart damage

Ascending UTI

-most common -infection travels from cystitis to pyelonephritis

Pneumonia

-most common form of infection of Streptococcus pneumoniae -characterized by fever and shaking chill, followed by signs that localize the disease to the lung -includes dyspnea, coughing purulent sputum, sometimes with blood -can progress to acute purulent meningitis if bacteria spread to the CNS -microaerosols transmission person to person

Treatment and prevention of neonatal GBS disease

-mothers are screened by selective culture -positive screening: given intrapartum IV prophylaxis -penicillin (or ampicillin) and an aminoglycoside for synergistic effects -current research into development of vaccine that targets GBS polysaccharide capsule

C. tetani virulence factors

-neurotoxin (tetanospasmin): blocks release of neurotransmitters for inhibitory synapses ==> rigid paralysis -spores are able to persist in soil or vegetation for years -C. tetani are part of normal intestinal flora for many animals

C. botulinum virulence factors

-neurotoxin: blocks excitatory neurotransmitter of cholinergic nerves (acetylcholine) ==> flacid paralysis -spores can persist in soil or vegetation for years and survive in contaminated food -cause foodborne (dying from improperly canned foods), wound, and infant botulism

Possible disease manifestations caused by a parasite infecting a host it is NOT well adapted to:

-non existent disease -similar, but less profound than in usual host -similar, but more profound than in usual host -quite different than in the usual host

Shigella characteristics

-non motile (no H antigen, no flagella) -does not ferment lactose -natural disease in humans and non-human primates; no animal reservoir -transmitted via fecal-oral route -very infectious: ID 10-100 organisms

Serologic diagnosis of Treponema after treatment

-non-treponemal: detect reaginic IgM and IgG antibodies; measures the flocculation of cardiolipin antigen by patient's serum -VDRL and RPR -most effective during secondary and latent stages -used successfully for screening and can be used as indicator of treatment success -seropositivity will wane over time

Mycobacteria general characteristics

-nonmotile; slender, slightly curved, rod-shaped bacilli -non spore forming -cell wall has high lipid content (mycolic acid) -resist de-colorization with Gram-stain (acid fast) -require complex media for growth -strictly aerobic -slow growers; those associated with disease take 2-6 weeks for growth -M. tuberculosis is enhanced by 5-10% CO2 -M. leprae fails to grow in vitro

C. trachomatis and N. gonorrhae testing in men

-nucleic acid amplification tests (NAATs) -a 1st catch urine specimen is recommended sample type and equivalent to a urethral swab in detecting infection -a urethral swab specimen for N. gonorrhae should be obtained and evaluated for antibiotic susceptibility in pts that: *have received CDC-recommended antimicrobial treatment *subsequently had a positive N. gonorrhae test result (positive NAAT >= 7 days after treatment) *did not engage in sexual activity after treatment

C. trachomatis and N. gonorrhae testing in women

-nucleic acid amplification tests (NAATs) -self or clinician-collected vaginal swab; self-collected are an option for screening if no pelvic exam is indicated -endocervical swab is acceptable when a pelvic exam is indicated -1st catch urine specimen is acceptable, but might detect up to 10% fewer infections when compared with vaginal and endocervical swab samples -an endocervical swab specimen for N. gonorrhae should be collected and evaluated for antibiotic susceptibility in pts that: *have received CDC-recommended antimicrobial treatment *subsequently had a positive N. gonorrhae test results (positive NAAT >= 7 days after treatment) *did not engage in sexual activity after treatment

What does pathogenicity of parasites depend on?

-number of parasites (parasite burden) -exposure and infection -ability to multiply in host (generally) *protozoa--YES *helminths--NO -regulation of intensity by host immune system or parasite -tissue specificity -mechanical effects -toxic effects -invasion and destruction of host cells -inflammatory (host immune) response to parasite or parasitic products -competition for host nutrients (with other parasites, flora, etc.)

Streptococcal impetigo

-occurs when transient skin colonization with GAS is combined with minor trauma (ex. inset bites) -characterized by small (up to 1cm) vesicle surrounded by area of erythema -vesicle enlarges over a pd of days, becomes pustular, and breaks to form a yellow crust

Principles of parasites

-often dependent on host-parasite relationship for species survival -co-evolution with specific host species -complicated life cycle -complex mechanisms of host entry, nutrition, and reproduction -complex interaction with host immune response

Shiga toxin (Stx1)

-only produced by S. dysenteriae and EHEC/STEC -AB toxin -MoA: toxin is transported into the cytosol, where it cleaves 28S rRNA, inhibiting protein synthesis -similar MoA to ricin toxin

Cytolethal distending toxin (CDT)

-only toxin VERIFIED to be encoded by C. jejuni -contributes to IL-8 release by epithelial cells -results in host cell DNA damage and cell cycle arrest leading to apoptosis -actual role in pathogenesis not fully known -other species that produce this toxn: E. coli, Heliobacter hepaticus, Haemophilus ducreyi, Shigella

Shet1 and Shet2 toxins

-other Shigella toxins encoded by gene on chromosome (Shet1) and plasmid (Shet2) -not as well characterized -contribute to initial watery diarrhea

Nutrition of parasites

-passive -active -may compete with host for nutrients

Borrelia burgdorferi

-pathogenic, helical-shaped spirochete -cause of Lyme Disease -multiple plasmids; some indispensable -large variety of lipoproteins -characteristic diminished expression of lipoproteins that is concurrent with host antibody response

Campylobacter pathogenesis

-penetrate mucosal layer of intestinal tract -attach to epithelium -invade epithelial cells -induce pro-inflammatory cytokines, such as IL-8

Treatment for GBS disease

-penicillin is primary treatment -B-lactam agents

Which combination of antibiotics are used to combat penicillin-resistant strains?

-penicillinase-resistant penicillins (methicillin, nafcillin, oxacillin) and 1st-generation cephalosporins -causes synergistic effect

Meningococcemia: on the skin

-petechiae (rash of small red or purple spots that do not disappear when pressure is applied to skin)--50-70% cases -rash may progress to larger red patches or purple lesions (similar to bruises) -most often found on trunk or extremities, but may progress to involve any part of the body -in severe cases, lesion may burst and lead to necrosis

Haemophilus virulence factors

-pili -outer membrane proteins (OMPs) -capsule *basis for vaccine (Hib) *contains polyribitol phosphate (PRP): surface polysaccharides *PRP is a T-cell independent antigen *capsule is conjugated to diphteria toxoid to improve immunogenicity in infants -endotoxin -no known exotoxins

Bordetella virulence factors

-pili, pertactin: for adherence -filamentous hemagglutinin (FHA): adherence, cytokine release, Th1 interference -pertussis toxin (PT): A-B toxin -adenylate cyclase (AC) -tracheal cytotoxin (TCT)

Acinetobacter

-pleomorphic, aerobic, Gram (-) bacillus (similar to haemophilus) -prefers aquatic environments (irrigating solutions, IV solutions) -in disease found mostly in organ systems with high fluid content: respiratory, CSF, urinary, etc. -low virulence; problematic in organ transplants; can cause neutropenia -inherently resistant to multiple antibiotics -recent emergence of strains resistant to all commercially available antibiotics

GBS disease manifestation

-pneumonia is common, and onset is typically 1st few days of life -nonspecific finding evolve to pneumonia and meningitis (late-onset) -maternal ad adult infections are rare, but can be serious if immune system is compromised

Pneumococcal conjugate vaccine (PCV)

-polysaccharide conjugated with protein -stimulates T-dependent Th2 responses -effective for children 2 months and older

alpha-hemolysin or alpha-toxin

-pore-forming cytotoxin that lyses the cytoplasmic membranes by direct insertion into the lipid bilayer to form transmembrane pores, leading to cell death -protein secreted by almost all strains of S aureus, but not by coagulase-negative Sstaphyloccoi

C. diff prevention

-prescribe and use antibiotics carefully; about 50% antibiotics given are not needed and may unnecessarily increase risk of C. diff infections -test for C. diff when pts have diarrhea while on antibiotics or within several months of taking them -isolate infected pts immediately -wear gloves and gowns while treating infected pts; hand sanitizer and hand washing are not sufficient -clean room surfaces with bleach or another EPA-approved, spore-killing disinfectant after a pt with C. diff has been treated there -when a pt transfers, notify the new facility if the pt has a C. diff infection

Embrel

-prescription medication (self-injected) for treatment of 5 long-term inflammatory diseases: *moderate-severe rheumatoid arthritis (RA) *adult chronic moderate-severe plaque psoriasis in pts who are candidates for systemic therapy or phototherapy *psoriatic arthritis *moderate-severe juvenile idiopathic arthritis (JIA) *ankylosing spondylitis (AS) -infections have occurred: tuberculosis (TB) and those caused by viruses, bacteria or fungi that have spread throughout body -pts should be tested for TB before, during, and after treatment with this drug

Peptic ulcer disease history

-prior to the 1980's, stress, diet and lifestyle were considered the major causes -Marshall and Warren noted small, curved bacteria colonizing lower part of stomach in pt biopsies -this organism was present in almost all pts w/gastric inflammation, duodenal ulcer, or gastric ulcer (Postulate 1) -inflammation noted in areas close to bacteria -Marshall was able to culture the organism (Postulate 2)

ETEC pathogenesis

-produce heat-stable (ST) and/or heat-labile (LT) enterotoxin -this stimulates guanylate or adenylate cyclase activity, increasing production of cAMP -activates PKA, opens CFTR, leads to fluid and electrolyte loss

Lepromatous leprosy

-progressive and malignant -organisms disseminate to all organs -extensive skin involvement: nodular skin lesions; nose deformities -nerve involvement not severe -no giant cells, no granuloma -poor Th1 response; elicits Th2 response

T. denticola virulence factors: dentilisin

-protease that mediates attachment and degrades the ECM

Lyme disease prevention

-protective clothing -use tick repellents (DEET-containing) -perform bodily tick checks when entering areas of risk -use preventative landscaping: remove brush and leaf litter; create a buffer zone of wood chips or gravel between forest and lawn or recreational areas -remove ticks promptly -seek medical care if characteristic rash appears

S. flexneri T3SS

-proteins assemble into a "syringe" to inject host cell with effector proteins -IpaC: actin polymerization -IpaB: cytoskeleton remodeling, ruffle formation, apoptosis -IpaA: localized de-polymerization of actin -IpaD: phosphatase -OspF: inactivates MAPK -VirA: GTP-ase activating; promotes escape from phagosome -VirG (IcsA): intracellular spread

Predisposing host factors to infection

-race, age, sex, genetic background -immune status affects ability of opportunistic fungal pathogens to establish infection *AIDS, cancer therapy, immuno-suppressive drugs for transplantation, antibiotic treatment can all increase susceptibility to infection

Parasites are self-regulatory in that they regulate:

-rate of maturation -population density (ex. Taenia solium) -response to host

Meningococcal meningitis: infants

-refusing feeds -increased irritability -sleeping all the time -fever -bulging fontanelle (soft spot on top of head) -inconsolable crying -epileptic fits (seizures)

WHO-ORS (low-osmolar ORS or reduced-osmolarity ORS)

-rehydration formula -formula: -2.6 g NaCl -2.9 g tri-sodium citrate dihydrate -1.5 g KCl -13.5 g anhydrous glucose/L of fluid

13-valent (PCV13) conjugate vaccine

-replaced the original 7-valent vaccine -stimulates Th2 in children

Leptospira transmission

-reservoir hosts: rodents, small mammals; colonize renal tubules and shed in large numbers in urine -incidental hosts: dogs, farm animals, humans; usually by recreational exposure to contaminated water or occupational exposure to infected animals -often transmitted by water contaminated with infected animal urine -veterinary vaccines (commercial bacterins) available -hamster model commonly used in research

Shigella pathogenesis

-resistant to gastric acidity -colonizes and invades colonic mucosa -causes acute inflammatory colitis with mucosal ulceration and abscess formation -invasion after entering M (microfold) cells -taken up by macrophages, but escapes from phagosome -induces macrophage apoptosis -invades epithelial cells via T3SS -in epithelial cells, polymerize actin ("comet" tails) to invade adjacent cells -invasion plasmid antigens (Ipa) and T3SS are encoded by a large plasmid (220kb) -cell to cell expansion destroys cells and causes ulceration and bleeding (bleeding + PMNs + ulcers + diarrhea = dysentery)

Jarisch-Herxheimer reaction

-results from complications in treating syphilis -high fever, rigors, cyanosis, and hypotension; mild to moderate in severity and self-limited -caused by rapid destruction of treponemes and release of endotoxins -can be distinguished from allergic reaction to penicillin by fever

Staphylococcal scalded skin syndrom

-results from production of exfoliatin in a staphyloccocal lesion from S. aureus -most common in neonates and children under 5 years -erythema and intraepidermal desquamation takes place at remote sites from which S. aureus can't be isolated

Chlamydia prevention

-risk reduction should be tailored to each individual's needs, risk factors, and abilities -abstinence -maintaining a monogamous relationship with a partner known to have no STIs -regular and proper use of latex and female condoms -avoid sex with multiple, casual partners and high-risk individuals (IV drug users, commercial sex workers, persons with multiple partners) -avoid high-risk practices (ex. condomless anal sex with someone with STIs

Prevention and treatment of cholera

-sanitation and hygiene -oral or parenteral re-hydration therapy -vaccines (none optimal): whole cell/B subunit; live-attenuated V. cholerae

S. epidermidis (novobiocin-S)

-second most common Staphylococcus spp. -Common cause of: • Nosocomial blood infections, which can lead to central nervous system (CNS) infections • Peritonitis in people on renal dialysis • Infections of replacement heart valves • Infection of long-term, indwelling venous catheters • Infection of prosthetic implants (hips, knees) -common colonizers of skin -form biofilms that are adhesive and protect bacteria from antimicrobial agents and host immune responses

Cytotoxin-associated gene A (CagA)

-secreted by H. pylori -highly immunogenic -CagA+ strains induce higher inflammatory response and are more likely to result in symptomatic outcome -prevents apoptosis of B cells, possibly contributing to gastric lymphoma

Osteomyelitis

-septic arthritis caused by staphyloccocal invasion of bones, joints, deep organs, and soft tissues, including surgical wounds -case study: Child with fever and localized pain and swelling below the right knee following orthopedic surgery; positive blood culture for S. aureus

CDC recommends chlamydia screening for:

-sexually active women age 25 or younger; test for each new partner -pregnant women: test during 1st prenatal exam -women and men at high risk: multiple partners, not always using a condom, possible exposure to someone with an STI

Chlamydiae trachomatis

-sexually transmitted bacterium that causes genital tract infections -obligate intracellular pathogen -Gram (-) type cell wall; no peptidoglycan -cross-linked outer membrane proteins provide stability -2 stage life cycle: reticulate body (RB-replicative form) and elementary body (EB-survival/transmissible form) -smaller than most bacteria

Group B streptococcus (GBS) or Streptococcus agalactiae

-short chains and diplococcal pairs of sperical/ovoid Gram-positive cells -B-hemolysin pore-forming toxin causes B-hemolysis -Lacefield B antigen -9 types of antigenic polysaccharide capsules (Ia, Ib, II-VIII) that contain sialic acid -leading cause of sepsis and meningitis in 1st few days of life -bacitracin-resistant

GBS capsule pathogenesis

-sialic acid moiety of the capsule binds serum factor H -this accelerated C3b degradation before it can be effectively deposited on the surface of the organism -inactivates alternative complement pathway and opsonophagocytosis

Tetanus treatment and prevention

-single serotype vaccine -immunity to tetanus involves antibodies to tetanus toxin; antibodies to the bacterial cell are not protective -tetanus toxoid is an excellent immunogen, but clinical tetanus does not induce immunity because so little toxin is released -therefore, actively immunizing pts on recovery is extremely important -wound debridement, passive immunization, and antibiotic therapy are appropriate

Treatment of Relapsing Fever (RF)

-single, large dose of erythromycin, tetracycline, or penicillin; but may induce a Jarisch-Herxheimer reaction

Yeast

-single-celled -divide by "budding" process -ex. Candida, Cryptococcus

Other infections caused by pneumococci

-sinusitis -odis media -endocarditis, arthritis, and peritonitis (usually in association with bacteremia) -does not cause pharyngitis or tonsillitis

Enteroinvasive E. coli (EIEC)

-site of action: large intestine -diseases: fever, cramps, watery diarrhea followed by dysentery with scant bloody stools -pathogenesis: plasmid-mediated invasion and destruction of epithelial cells lining the colon

Enterohemorrhagic E. coli (EHEC)

-site of action: large intestine -diseases: hemorrhagic colitis with severe abdominal cramps, watery diarrhea followed by bloody diarrhea, little or no fever, hemolytic uremic syndrome (HUS) -pathogenesis: Shiga-like toxin

Enterotoxigenic E. coli (ETEC)

-site of action: small intestine -diseases: Traveler's diarrhea, infant diarrhea in underdeveloped countries, cramps, low grade fever -pathogenesis: heat-stable (ST) and/or heat-labile (LT) toxin; stimulates production of cAMP, leading to great water and electrolyte loss

Enteropathogenic E. coli (EPEC)

-site of action: small intestine -diseases: infant diarrhea with fever, nausea, vomiting, non-bloody stools -pathogenesis: plasmid-mediated adherence and destruction of epithelial cells

Enteroaggregative E. coli (EAggEC)

-site of action: small intestine -diseases: persistent infant diarrhea, sometimes with gross blood; low grade fever -pathogenesis: aggregative adherence

Bordetella pertussis

-small Gram (-) diplococci or coccobacilli -oxidase (+) -encapsulated -strictly human pathogen -Fastidious (growth only on specialized medium with nicotinamide and charcoal: Bordet-Gengou agar) -Causes whooping cough, primarily in unvaccinated children and adults with waning immunity; highly contagious. -Vaccine: DTaP -bacteria stay localized in tracheobronchial tree -rapid diagnostic test (PCR, DFA) -treatment: Azithromycin, Erythromycin

Mycoplasma/Ureaplasma common features

-smallest organisms capable of growth on cell-free media -smallest genomes known -lack a cell wall (unique among prokaryotes) -no LPS or peptidoglycan -pleiomorphic: unusual morphology *asymmetrical shape with tailing/gliding end and attachment organelle at the other end -outer membrane triple-layered structure of lipids and proteins *contains sterols--unique among bacteria *sterols enhance stability of membrane *also help resist osmotic stress *must be supplied in cell growth medium *resistant to action of B-lactams

Thermal dimorphism

-some fungi can exist as both yeasts and molds by adapting to their environment -at high temperatures (about 37 deg. C), exist as yeasts -at lower temperatures (25 deg. C), exist as mold

What conditions need to be in place for someone to get infected by Ascaris?

-someone in the community has to have patent infection -infected person leaves stool on the ground, in appropriate conditions -stool must remain in that spot while eggs mature -another person (victim) has to ingest those eggs *from food contaminated with soil containing eggs *from contaminated hands *from water contaminated with stool and eggs (less common)

Group A streptococcus (GAS) or Streptococcus pyrogenes

-spherical or ovoid cells in chains of short-medium length -Beta-hemolysis caused by 1 of 2 hemolysins: streptolysin S and the oxygen-labile streptolysis O -cell wall: peptidoglycan matrix provides rigidity -group carbohydrate antigen lies within peptidoglycan matrix -group A carbohydrate -M protein and lipoteichoic acid (LTA) attached to wall -LTA and protein F mediate binding to fibronectin on host surface -many have a nonantigenic hyaluronic acid capsule -pili aid with adhesion to host cell surface -responsible for scarlet fever (StrepSAgs) -cause of "strep throat", pharyngitis in children -mostly susceptible to penicillin G

Antistreptolysin O (ASO)

-standard serologic test for GAS bacteria -uses quantification of antibodies against streptolysin O as a basis -ASO antibodies document previous infection in suspect ARF

Meningococcal meningitis: children >1 year and adults

-stiffness in neck -headaches -nausea and vomiting -neck and/or back pain -fever and chills -increased sensitivity to light -irritability, confusion

Th2 cell response

-stimulated by helminths -eosinophil response; cells secrete IL-4 -IL-12 and IL-5 also secreted to help control infection

Th1 cell response

-stimulated by protozoa, bacteria, and viruses -involves macrophages, NK cells, and granulocytes -Th cell secretes IFN-gamma and IFN-Beta -no eosinophils

Helicobacter diagnosis

-stool samples -urease production tests: Helicobacter breath tests and Campylobacter-like organism (CLO) test

Common features of the 2 types of MRSA

-strains rose independently worldwide -highly communicable -Staphylococcal cassette chromosome mec (SCCmec) elements that encode methicillin resistance -type IV most prevalent in CAMRSA -P-V leukocidin that attack neutrophils (rare in HAMRSA) -P-V leukocidin transferred by bacteriophage -Resistance is plasma-mediated -sensitivity to most other antibiotics except beta-lactams

Which 2 hemolysins cause Beta-hemolysis in GAS strains?

-streptolysin S and O

Mycology

-study of "mykos" or "mycetes" (Greek for mushroom) -members of Kingdom Fungi -large and diverse group of organisms with extensive ecological distribution

Necrotizing fascitis

-suppurative infection caused by S. pyogenes - rapidly expanding area of erythema, bulla formation, and anesthesia around a recent wound on the arm, which leads to tissue destruction; accompanied by fever and other evidence of systemic toxicity (possible shock and multisystem organ failure) -"flesh-eating" disease

Active TB

-symptoms: fever, cough (usually with bloody sputum), weight loss, fatigue, night sweats -eventually leads to irreversible lung damage -bacteria can escape from lungs to cause systemic disease

UTI diagnosis

-take history, symptoms, and urinalysis -urine culture shows > 10^3 colony-forming units (CFU)/mL of urine -urine dipsticks -in recurrence UTI: ultrasound, cytoscopy -intravenous pyelogram

Metazoans (or helminths)

-the "big ones"

Protozoan parasites

-the "little ones"

Penicillin minimal inhibitory concentration (MIC)

-the amount of penicillin required to inhibit pneumococcal strains, which is increasing as more strains develop resistance

Capsule switching

-the antigenic of the capsule makeup of S. pneumoniae changes -possibly due to in vivo transformation and recombination with external DNA

Dirofilaria Immits

-the cannine heartworm -transmitted from vectors during blood meal to dogs; completely mature in the cannine -female worms produces microfilariae in heart, which is transmitted through the blood and taken up by arthropod during next blood meal

Host

-the harboring species for a parasite -may show no effect from the parasite or may suffer from various disease states

Treponema general characteristics

-thin, tightly coiled spirochete, with pointed, straight ends -does not stain with Gram or Giemsa stain due to thinness -microaerophilic -can't be cultured; only limited success with tissue culture -generation time: 30 hrs or more

Ehrlichia/Anaplasma

-tick-borne; obligate intracellular -disease: ehrlichiosis *HME: Human monocytic ehrlichiosis (Ehrlichia chaffeensis) *HGA: Human granulocytic ehrlichiosis (Anaplasma phagocytophilum) -nonspecific presentation: fever, headache, myalgia -Clinical manifestations similar to Rocky Mountain Spotted Fever but often without rash ("Spotless spotted fever") -May have co-existent infection with other tick-borne infections: Lyme disease, RMSF, Babesiosis -cause lysis of host cells and re-infection of neighboring cells -biphasic life cycle: *dense cells (DC) *reticulate cells (RC) -diagnosis: *cell wall lacks PG and LPS (Giemsa stain) *inclusion bodies (morulae) inside WBCs; serology (PCR)

Diagnosis of leprosy

-tissue and skin scrapings -cannot be grown on artificial medium -diagnosis based on clinical symptoms and positive acid-fast smears of scrapings

Pathogenesis of tetanus

-toxin elaborated in a local wound migrates to site of infection -toxin acts at several sites in CNS, including peripheral motor end plates, spinal cord, and brain -symptoms arise when tetanus toxin interferes with release of neurotransmitters, blocking inhibitor impulses -leads to unopposed muscle contraction and spasm; seizures may occur, and the ANS may also be affected -the enzymatic portion of tetanus toxin is a zinc-requiring endopeptidase that cleaves SNARE proteins (synaptobrevin, SNAP-25, syntaxin) found in secretory vesicles -death usually occurs due to interference of mechanics of respiration

C. perfringens enterotoxin (CPE) mechanism

-toxin produced when bacteria sporulates in intestine -toxin binds to claudin receptors to form a small complex -those small complexes then oligomerize to create a hexameric prepore on the membrane surface -Beta hairpin loops from CPE molecules in the prepore assemble into a beta-barrel that inserts into the membrane to form an active pore that enhances calcium influx --> apoptosis of cell -cell death is result of intestinal damage caused by fluid and electrolyte loss

Ergot alkaloids

-toxins produced by Claviceps when growing in grains -also hypothesized that these toxins were accidentally inhaled by women working in the grain fields in Salem, causing hallucinations and having them be mistaken as witches

Staphylococcal enterotoxins

-toxins that stimulate gastrointestinal symptoms (mainly vomiting) -stable and retain activity even after boiling or exposure to stomach or intestinal enzymes

M. pneumoniae pathogenesis

-transmission by aerosol droplets -"cytadherence": attachment to ciliated epithelium via P1 adhesion (receptor: specific, sialic-acid containing) -do NOT enter cells, but burrow down between them and are found in intercellular spaces -cause "ciliostasis" and epithelial necrosis: after attachment, there is a decline in RNA synthesis in host cell; cilia stop beating -superficial epithelia in upper airway destroyed and microbes can infect the lower respiratory tract -inflammatory response stimulated with membrane lipoprotein -not a commensal bacterium; isolation is always significant and pathognomonic -low infectious dose (highly infectious)

Wound infections caused by streptococci

-transmission is from patient-patient by hands of healthcare providers who do not wash hands -more common in developing countries

Progression of TB

-transmission via aerosol droplets -primary TB --> latent TB --> "reactivation" TB -primary: rare, unless immunocompromised due to lack of CD4+ cells (ex. HIV pts) -latent: most common; majority of cases progress to this infection *5% chance of developing "active" TB within 2 years of latent infection; *if no infection after 2 yr pd., 5% of developing active infection over lifetime *with HIV: chances of re-activation are 10% each year

Pathogenesis of Legionella

-transmitted by aerosol droplets -target alveolar macrophages: attach via pili and OMPs -survive and multiple in a vacuole after being ingested by macrophages -induction of apoptosis and pore-forming toxin leads to death of host cell -causes destructive lesions and cytokine release (systemic)

Botulism treatment and prevention

-treatment usually with antitoxin and supportive therapy (ex. respirators) -outcome depends on amount of ingested neurotoxin and how quickly treatment is started -infant and wound botulism: antibiotics that kill the bacteria and antitoxin to neutralize circulating neurotoxin -boiling food for 10 min prior to consumption can inactivate the toxin, but will not kill the spores -best prevention for foodborne botulism is proper food processing, which kills spores -no practical vaccine due to rareness of disease, multiple serotypes, and inability to identify at-risk individuals

Gas gangrene treatment and prevention

-treatment: usually debridement and excision with amputation necessary in many cases -antibiotics alone are not effective because they do not penetrate ischaemic muscles enough to be effective; however, penicillin is given as an adjunctive treatment to surgery -hyperbaric oxygen therapy (HBOT) is also used and acts t inhibit the growth of and kill the anaerobic C. perfringens

Phylum Platyhelminthes (flatworms)

-type of metazoa -Class Cestoda (tapeworms) *beef, pork, and fish tapeworms *Hydatid disease -Class Trematoda (flukes) *liver, blood, lung, and intestinal flukes

Phylum Nemathelminthes (roundworms)

-type of metazoa -Class Nematodes: *intestinal nematodes (roundworms, hookworms, pinworms, etc.) *blood and tissue nematodes --> filaria (filariasis, river blindness, loaiasis) ---> Guinea worm

S. boydii

-uncommon, 20 serotypes

Infections associated with N. gonorrhoeae

-urethritis -cervicitis -salpingitis -proctitis -septicemia -arthritis -PID -conjunctivitis -pharyngitis

Clinical conditions that promote opportunistic infections

-use of broad-spectrum antibiotics for an extended time (Candida, part of normal flora) -therapeutic use of immunosuppressive drugs (ex., transplantation) -radiation therapy for cancer -loss of helper T cell function (AIDS) -cancer, severe burns, infectious diseases that decrease immunity -neutropenia -diabetes and physiological deficiencies

Water bath canning

-used for canning high acid foods (pH 4.6 or lower) -examples: fruits, most soft spreads, tomatoes with added lemon or citric acid, pickles

Pressure canning

-used for canning low acid foods (pH > 4.6) -examples: meats, seafood, poultry, dairy products (though canning generally not recommended), vegetables, soups and meals

Ziehl-Neelsen acid-fast stain

-uses heat to force stain into bacilli -carbol fuchsin/methylene blue -organisms stain red

Pathogenesis of foodborne botulism (intoxication)

-usually associated with improperly-canned food b/c temperatures are not high enough to kill spores, which can then germinate and grow in the anaerobic environment of the jar/can -bacteria multiply and produce neurotoxin, which is ingested with the food -toxin is absorbed from the stomach and attacks peripheral neurons where it blocks neurotransmitter release -symptoms: double vision, blurred vision, droopy eyelids, slurred speech, dysphagia, dry mouth, and muscle weakness -symptoms generally begin 18 to 36 hours after eating contaminated food, can occur as early as 6 hours or as late as 10 days

Tuberculous leprosy

-usually self-limiting -single skin lesions -nerve involvement: patches of anesthesia from inflammatory response -organisms rarely found in tissues -histology: granuloma, giant cells -elicits strong Th1 response

Haemophilus

-very small, Gram (-) coccobacilli -require hematin (X-factor) and NAD (V-factor) for culture (chocolate agar or special medium) -2 major species: *H. influenzae *H. ducreyi -strictly human pathogen -vaccine available for H. influenzae type B (Hib)

Protein A

-virulence factor unique to S. aureus bacteria -surface protein -binds the Fc portion of IgG molecules, leaving the antigen-reacting Fab portion directed externally (turned around) -also able to stimulate cytokines (TNF-α), platelets, and B cells -Anti-opsonic and anti-phagocytic

Treponemal adhesins (OMPs)

-virulence factors that aid T. pallidum in invasion of host cell -located on pointed ends of cell -recognize and bind to fibronectin, a glycoprotein on eukaryotic cell surfaces -also helps bacteria attach to laminin and collagen in the basement membrane

Clinical symptoms of C. diff infection

-watery diarrhea -fever -loss of appetite -nausea -dehydration -abdominal pain/tenderness

C. jejuni transmission

-zoonotic pathogen; commensal in chicken and other avian species -colonizes chicken intestine at 10^10 CFU/gram infected tissue -thermophilic nature reflects adaptation to avian host -ingested of contaminated and/or under-cooked poultry, meat, or unpasteurized milk -direct contact with domestic animals -contaminated water

Direct Coombs (antiglobulin) test

1) Blood sample obtained from pt with immune-mediated hemolytic anemia 2) Pt's washed RBCs are incubated with antihuman antibodies (Coombs reagent) 3) Positive test: RBCs agglutinate; antihuman antibodies form links between RBCs by binding to the human antibodies on the RBCs

Leptospira pathogenesis

1) Penetrate intact mucous membrane or through broken skin 2) Hematogenous spread 3) Dissemination - tropism for liver, kidney, and CNS 4) Leptospires shed in urine

Indirect Coombs (antiglobulin) test

1) Recipient serum is obtained, containing antibodies (Ig's) 2) Donor's blood sample is added to a tube with serum 3) Recipient's Ig's that target the donor's RBCs form antibody-antigen complexes 4) Antihuman Ig's (Coombs reagent) are added to the solution 5) Positive test: agglutination of RBCs occurs b/c human Ig's are attached to RBCs

4 possible outcomes of Mtb infection

1) immediate clearance of organism 2) primary disease soon after infection 3) latent infection that never re-activates 4) re-activation disease

Stages of pertussis

1) incubation: 7-10 days; no symptoms 2) catarrhal: 1-2 weeks; rhinorrhea, malaise, fever, sneezing, anorexia (most bacteria detected in culture at this stage) 3) paroxysmal: 2-4 weeks; repetitive "whooping" cough, vomiting, leukocytosis 4) convalescent: 3-4 weeks (or longer); diminished paroxysmal cough, possibly secondary complications (pneumonia, seizures, encephalopathy)

Which component is present in fungi? 1. Ergosterol 2. Lipid A 3. Peptidoglycan 4. Teichoic acid 5. 70S ribosome

1. Ergosterol

Suzie, a 7-year-old girl, who previously had been in good health, develops fever, headache, and a dry cough while on summer break. Her 12-year-old brother has had similar symptoms ca. 3 weeks earlier. Over the next 2 days, her temperature increases and the cough worsens, producing small amounts of clear sputum. She appears slightly pale and has a temperature of 38.6°C (101.5F) and a respiratory rate of 40 bpm (N: 15-30). Scattered rales (abnormal respiratory sounds) were heard through the stethoscope over the left posterior lung. Her white blood cell count was in the normal range, 8,600 per μL (N: 4,000-12,000), with a normal differential count. She was slightly anemic (hematocrit of 29%, N:33-43%) and had an increased number of reticulocytes. A Gram stain of her sputum revealed only a few neutrophils and no bacteria. A chest radiograph showed bilateral, patchy infiltrates. A rapid test for IgM antibody to the causative agent was positive. This finding and the clinical picture allowed the tentative diagnosis of primary atypical pneumonia. Suzie was treated with azithromycin and made an uneventful recovery. 1. What is the differential? 2. What is unusual about this respiratory illness? 3. How did she acquire the organism? 4. What are distinguishing features of the organism and the treatment process? 5. How can a definitive diagnosis of mycoplasmal infection be made?

1. Mycoplasma; not viewable by Gram stain 2. normal WBC range, dry cough, symptoms developed 3 weeks after exposure (from brother), elevated respiratory rate, increased number of reticulocytes 3. acquired from her brother, though the bacteria took some time to manifest 4. cannot be viewed by Gram-stain 5. bacteria is too small to be viewed by Gram-staining; slow growing bacteria, dry cough

Which statement regarding fungal growth and morphology is correct? 1. Pseudohyphae are produced by all yeasts 2. Molds produce hyphae that may or may not be partitioned with cross-walls or septa 3. Conidia are produced only by sexual reproduction 4. Most yeasts reproduce sexually and lack cell walls 5. Most pathogenic dimorphic molds produce hyphae in the host and yeasts in nature.

2. Molds produce hyphae that may or may not be partitioned with cross-walls or septa

Cholera causes an osmotic imbalance due to inhibition of Na+ absorption and secretion of Cl- into the lumen of the bowel that can result in up to _______ a day of "rice-water" stool and fatal dehydration.

20 liters

Which statement regarding fungi is correct? 1. All fungi are able to grow as yeasts and molds 2. Although fungi are eukaryotes, they lack mitochondria 3. Fungi are photosynthetic 4. Fungi have one or more nuclei and chromosomes 5. Few fungi possess cell membranes

4. Fungi have one or more nuclei and chromosomes

Which of the following mycotoxins is the most potent natural carcinogen of fungal origin and can also cause acute liver failure? 1. Psilocybin 2. Fumonisin 3. Ergot alkaloids 4. T-2 5. Aflatoxin B1

5. Aflatoxin B1

A febrile patient presents with diarrhea containing both blood and pus. The lab cultures on a special medium incubated at 42°C under microaerophilic conditions grow a Gram-negative spiral-shaped organism that is isolated. What is the most likely genus? A. Campylobacter B. Helicobacter C. Vibrio D. Bacillus E. Escherichia

A. Campylobacter

A 36-year-old man presents to his primary care physician's office complaining of fever and headache. On examination, he has leukopenia, increased liver enzymes, and inclusion bodies are seen in his monocytes. History reveals that he is an avid hiker and he remembers removing a tick from his leg after his last trip into the Virginia woods. Which of the following is the most likely diagnosis? A. Ehrlichiosis B. Lyme disease C. Q fever D. Rocky Mountain spotted fever E. Tularemia F. I don't know

A. Ehrlichiosis

A 4-year-old boy is taken to see his pediatrician because of a persistent cough that gradually worsened over a 12-day period. On the day of the examination, the cough is so severe that it is frequently followed by vomiting. A blood cell count shows marked leukocytosis with a predominance of lymphocytes. Which of the following best characterizes this microorganism? A. It produces a toxin that increases cAMP levels, resulting in increased mucus production B. It produces a toxin that blocks protein synthesis in an infected cell and which is carried on a lysogenic phage C. It secretes an erythrogenic toxin that causes the characteristic signs of scarlet fever D. It secretes peroxide which destroys ciliated cells E. It produces an exotoxin that causes unspecific binding of APCs and T-cells F. I don't know

A. It produces a toxin that increases cAMP levels, resulting in increased mucus production

A patient had surgery 6 months ago to put in a pacemaker. He felt fine initially, but over the past month, he has been feeling worse. He is running a low-grade fever, tires easily, and has worsening heart murmurs. A gram-positive, catalase positive, coagulase negative, novobiocin sensitive bacterial strain was isolated. Which of the following is the most likely causative organism? A. Staphylococcus epidermidis B. Streptococcus pyogenes C. Staphylococcus aureus D. Streptococcus pneumoniae E. Staphylococcus saprophyticus F. I don't know

A. Staphylococcus epidermidis

A 5-y/o girl comes to the clinic with fever, inflamed throat with possible exudates, general malaise, cervical lymphadenopathy, and no coryza. On examination, a grayish-white exudate is seen on her tonsils and pharynx. A culture of the exudate reveals a catalase-negative, gram-positive, bacitracin-sensitive coccus that grows in chains. A primary mechanism responsible for the pathogenesis of the girl's disease is which of the following? A. Action of Protein A B. Action of M protein C. Action of sIgA1 protease D. Action of Lipid A E. Action of pneumolysin F. I don't know

B. Action of M protein

A 14 month old boy is brought in by his parents with fever, fussiness, lethargy, and apparent headache. On examination, his neck is stiff. His parents have not given him his routine childhood vaccines due to concerns of autism. Very short gram-negative rods are seen in the CSF, so antibiotics are immediately started. The organism grows on chocolate agar but not blood agar. No one else in the family is ill. What is the most likely causative agent? A. Escherichia coli B. Haemophilus influenzae type b C. Klebsiella pneumoniae D. Neisseria meningitidis E. Streptococcus pneumoniae F. I don't know

B. Haemophilus influenzae type b

A 42 y/o man comes to the ED with complaints of sudden onset fever, myalgia and dyspnea. He is a cattle farmer and lives in rural Montana. On PE his temperature is 38.2°C. No rash is noted. Scattered rales are heard on auscultation. He does not recall having been bitten by any insects in the last few weeks. Which of the following rickettsial diseases has he most likely contracted? A. Brill- Zinsser disease B. Q fever C. Rickettsial pox D. Rocky Mountain spotted fever (RMSF) E. Scrub typhus F. I don't know

B. Q fever

A child presents with impetigo with bullae. A gram-positive, catalase-positive, coagulase-positive coccus is isolated. Which of the following is the most likely organism? A. Streptococcus pyogenes B. Staphylococcus aureus C. Streptococcus agalactiae D. Staphylococcus epidermidis E. I don't know

B. Staphylococcus aureus S. aureus is gram-positive, catalase-positive (not found in Streptococcus) and coagulase positive.

A young woman recently underwent rhinoplasty to correct a deviated septum and her nose was packed postoperatively. She experienced a 3-day period of low-grade fever, muscle aches, chills, and malaise. This was followed by the development of a sunburn-like rash that covered most of her body including her palms and soles. The packing was removed and a nasal swab grew gram-positive cocci that were catalase-positive and produced colonies on mannitol-salt agar that were surrounded by a yellow halo. The bacteria clumped when mixed with rabbit plasma. What is your diagnosis? A. Scalded skin syndrome B. Toxic shock syndrome C. Scarlet fever D. Necrotizing fasciitis E. Impetigo F. I don't know

B. Toxic shock syndrome

Which of the following parasites would be most likely to cause eosinophilia? A. Plasmodium falciparum B. Wuchereria bancrofti C. Naegleria fowleri D. Entamoeba histolytica

B. Wuchereria bancrofti

Why are Vibrio difficult to Gram-stain in stool samples?

Because all you see is a shit-load of Gram (-) rods

An 18 mths old boy who has received no vaccines because of parental fear of autism develops S. pneumoniae meningitis. Which vaccine should he have received to prevent his illness? A. An inactivated whole cell vaccine B. A 23-valent polysaccharide vaccine C. A conjugate (protein-polysaccharide) vaccine D. A toxoid vaccine E. A DNA vaccine F. I don't know

C. A conjugate (protein-polysaccharide) vaccine

Regarding the first case study (kid with 'strep throat'): If untreated, which other sequelae could most likely occur? A. Endocarditis B. Impetigo C. Acute rheumatic fever D. Acute glomerulonephritis E. Necrotizing fasciitis F. I don't know

C. Acute rheumatic fever

A 1-year-old boy is brought to his pediatrician with a severely inflamed cut on his knee. He has had four ear infections in the past year, and several additional wound infections that generally respond to topical therapy. Culture of the current wound reveals gram-positive cocci that are catalase-positive and coagulase-positive. Protein A, a determinant of pathogenesis for these bacteria ....? A. Is required for attachment to epithelial tissue. B. Is a superantigen. C. Binds to the Fc portion of immunoglobulin G. D. Is a cytotoxin. E. Is an exo-enzyme that aids in spreading of bacteria through tissue. F. I have no idea

C. Binds to the Fc portion of immunoglobin G

A 75 year old man with a one week history of fever, rash and headache comes into the office. He reports that the rash started in the axillary folds and his upper trunk and then spread to the rest of his body, sparing face, palms and soles. An exam shows a maculopapular rash. The patient further states that this is similar to, but not as bad as, an illness he had when he was in Poland just after WWII ended. What is this disease called? A. Rocky Mountain spotted fever B. Endemic typhus C. Epidemic typhus D. Brill-Zinsser disease E. Rickettsialpox F. I don't know

C. Epidemic typhus OR D. Brill-Zinsser disease (better answer)

The best way to remove an attached tick is: A. Burn it off with a hot match B. Apply petroleum jelly C. Grasp the tick with tweezers close to the skin and pull D. "Painting" the tick with nail polish E. All of the above work

C. Grasp the tick with tweezers close to the skin and pull

Of the species of human Plasmodia, P. falciparum causes most severe morbidity and mortality, whereas other species such as vivax, ovaleand malaria ecause relatively mild disease. From an evolutionary standpoint, what is a likely explanation? A. Falciparum parasites are better adapted to humans B. Humans are not primary hosts for the non-falciparum parasites C. Humans became hosts for falciparum parasites more recently than for other species

C. Humans became hosts for falciparum parasites more recently than for other species

Mycoplasmas have all of the following characteristics except: A. Possession of DNA and RNA B. Capability of cell-free growth C. Susceptibility to Penicillin G D. Extracellular parasitism in vivo E. I don't know

C. Susceptibility to Penicillin G

An 18-month-old male presents with fever, lethargy, malaise, productive coughing, and vomiting. Culture of cerebral spinal fluid samples with Staphylococcus aureus on blood agar reveals the presence of "satellite" colonies. Serology has indicated that the organism is polyribitol phosphate (PRP) positive. Gram stain of the colonies indicates the presence of a gram-negative coccobacillus. Which one of the following organisms is most likely responsible for the disease? A. Bordetella pertussis B. Campylobacter jejuni C. Escherichia coli D. Haemophilus influenzae b E. Pasteurella multocida

D. Haemophilus influenzae b

The Plasmodiumspecies which cause human malaria undergo 2 cycles of replication. In the human, a single parasite divides asexually into multiple parasites. In the mosquito, male and female gametocytes fuse to form diploid zygotes, which eventually divide into individual parasites. Given this scenario, humans are which type of host? A. Incidental B. Paratenic C. Definitive D. Intermediate

D. Intermediate -this host harbors the malaria in an arrested stage of development (diploid zygotes that will eventually divide into mature parasites)

Which of the patient's findings are most unique for pertussis? A. Cough B. Choking C. Vomiting D. Lymphocytosis E. I don't know

D. Lymphocytosis

A week after returning from a July camping trip to the Blue Ridge mountains in North Carolina, a 10-year-old boy is brought to the ED with a severe headache, fever, and muscle pain. He also has a maculopapular rash on his arms and legs. Although the rash began on his arms and legs, it has now spread to his trunk. He remembers removing several ticks from around his ankles on the camping trip. What is the organism most likely to the cause of this young man's infection? A. Coxiella burnetii B. Streptococcus pyogenes C. Rickettsia prowazekii D. Rickettsia rickettsii E. Borrelia burgdorferi F. I don't know

D. Rickettsia rickettsii

The fungal disease classically associated with erythematous nodules present along the lymphatics on the extremities is: A. Aspergillosis B. Coccidiodomycosis C. Mycotoxicosis D. Sporothricosis E. Histoplasmosis

D. Sporothricosis

A 47 y/o woman with AUD (alcohol use disorder) presents complaining of chest pain, fever, shaking chills, cough, and myalgia. She felt very cold two nights ago and says she has felt "poorly" ever since. Her cough is producing rust-colored, odorless, mucoid sputum. Her temperature on admission is 40°C (104F). Blood analysis shows leukocytosis. An α-hemolytic, lancet-shaped, gram-positive, optochin sensitive diplococcus is isolated on blood agar. A primary mechanism responsible for the pathogenesis of the woman's disease is: A. Action of Protein A B. Action of M protein C. Action of Catalase D. Action of Lipid A E. Action of pneumolysin F. I don't know

E. Action of pneymolysin

A neonate develops septicemia at 7 days of age. Her mother is 16 years old, single, has had multiple sexual partners without barrier protection, had no prenatal care and lives in the US. The baby was born 23 hours after the mother's amniotic sac ruptured. Culture on blood agar plate yields Gram-positive beta-hemolytic colonies that are catalase negative and resistant to bacitracin. What is the most likely causative agent? A. Staphylococcus saprophyticus B. Streptococcus pyogenes C. Staphylococcus aureus D. Streptococcus pneumoniae E. Streptococcus agalactiae F. Stapylococcus epidermidis G. I don't know

E. Streptococcus agalactiae

______ is capable of fermenting lactose, appearing as a red colony on MackConkey agar.

E. coli

Pathogen responsible for Chipotle crisis

E. coli O26

Pathogen responsible for Costco chicken salad crisis

E. coli O:157:H7

Antimycotics that inhibit B-1,3 glucan synthesis

Echinocandins

What is the most common etiologic agent in Traveler's diarrhea?

Enterotoxigenic E. coli (ETEC)

Antimycotics that block DNA synthesis

Flucytosine

Antimycotics that block microtubule activity

Griseofulvin

Antigen for Enterobacteria flagellum

H antigen

______ cytokine is released by epithelial cells and is generally associated with Campylobacteriosis. Its secretion signals neutrophils, macrophages, and DCs to site of infection.

IL-8

Pneumonia

Individual suddenly develops fever, difficulty breathing, and empyema (intrapleural abscesses) soon after recovering from influenza.

Antigen for Enterobacteria capsule

K antigen

Antigen for Enterobacteria LPS

O antigen

Surface antigens of Enterobacteria that are basis for serotypes

O, H, and K antigens

Treatment used to prevent recurrent ARF episodes

Penicillin prophylaxis

The only Shigella species that produces Shigatoxin, causing hemolytic uremic syndrome

S. dysenteriae

________ and ________ are incapable of fermenting lactose, appearing as white colonies on MacConkey agar.

Salmonella, Shigella

A 6 month old infant is brought to the office with blister like lesions widely disseminated over his body. Large areas of desquamated epithelium but no scarring is observed. Toxin? Method of action?

Scalded skin syndrome in neonate -toxin: exfolatoxin -method of action: exfoliative toxin takes at least a few days and may exert its effect locally or systemically -toxin absorbed at infection site reaches its infant stratum granulosum binding site through the circulation causing widespread desquamation by its action on the keratinized epidermis as in the staphylococcal scalded skin syndrome -infants have more Dsq-1 than adults, making them more susceptible to this disease

A 9 y/o child is brought to the pediatrician with a 6 day history of fever, inflamed throat with possible exudates, general malaise, cervical lymphadenopathy, and no coryza (acute rhinitis) [often indistinguishable from viral infection]. The boy had developed a bright red tongue and a diffuse sandpaper-like erythematous rash over his body about 36 hrs after onset of pharyngitis. Amoxicillin is prescribed. The mother reports that the rash faded 6 days later, with desquamation. What condition did the boy experience following strep throat?

Scarlet feverAut

Bacteria that: -Most common cause of community-acquired pneumonia -Most common cause of otitis media (ear infections) -Most common cause of sinus infections -Leading cause of bacterial meningitis in adults -Infections can result from organisms carried in the URT, e.g., Following viral infection (influenza)

Streptococcus pneumoniae

Protozoans usually elicit a _____ immune response

Th1 (no eosinophilia except in rare cases)

Helminths usually elicit a _____ immune response

Th2 (eosinophils present and migrate toward site of infection)

Why is gram staining not helpful when identifying spirochetes?

The width of many spirochetes is at or just below the resolving power of a light microscope. They are usually observed by dark-field microscopy.

Most common cause of UTIs

Uropathogenic E. coli (E. coli) cause more than 90% of cases

Furunculosis

a complication of acne vulgaris

Mycosis

a disease caused by a fungus

Role of peptidoglycan in Helicobacter infection

activates innate immune response upon entry into host cell

TFN-a and MCP-1 response to Mtb

activation and recruitment for granuloma formation

Coagulase

an enzyme which binds prothrombin in a manner that provides for the cleavage of fibrinogen to fibrin

Parasite

an organism that depends upon a host for nutrition and shelter for some or all of its life cycle

The basic human habitat of S. aureus is the _________

anterior nares

IFN-gamma response to Mtb

anti-mycobacterial effector functions

True fungal pathogens

can invade and grow in a healthy, immunocompetent host

Facultative parasite

can lead free and parasitic existence

Enterotoxin secreted by V. cholerae

cholera toxin (CT)

Obligate parasite

completely dependent on host(s)

What invertible DNA element controls phase variation of Type 1 fimbriae in E. coli?

fimS

Intermediate host

harbors one or all of the larval or asexual stages

Definitive host

harbors the adult or sexual stage of the parasite

Paratenic host

harbors the parasite in an arrested stage of development until it can continue development in the next suitable host

The more co-evolved a parasite is with its host(s), the _______ likely a disease will manifest

less

gamma-hemolysis

no hemolysis

_______ is the treatment of choice for susceptible S. aureus strains

penicillin G

________ and ______ are antibiotics that work against S. aureus cell wall peptidoglycan and vary in their susceptibility to inactivation by staphylococcal B-lactamases

penicillins and cephalosporins

IL-12 response to Mtb

polarization to Th1

Incidental host

species that is not the usual (principal) host, but which may become parasitized

Principal host

species that is the most common for a parasite

Hyaluronidase

spreading factor in GAS

Expediated partner therapy (EPT)

the clinical practice of treating the sex partners of patients diagnosed with chlamydia or gonorrhea by providing prescriptions or medications to the patient to take to his/her partner without the healthcare provider first examining the partner