micro exam 4

causes of epiglottitis

h. influenzae type B

RSV clinical syndrome

- bronchiolitis, pneumonia, or both: fever, cough, dyspnea, cyanosis in children <1; pneumonia in elderly or those with chronic heart disease, chronic lung disease, or immunocompromised - bronchiolitis is characterized by low grade fever, tachypnea, tachycardia, and expiratory wheezes over lungs - febrile rhinitis and pharyngitis: in children - common cold: in older children and adults

most common cause of LRI in young adults

m. pneumoniae

how does influenza virus differ from most RNA viruses

***the influenza virus transcribes and replicates its genome in target cell nucleus: the influenza nucleocapsid travels to the nucleus where it is transcribed into mRNA, the transcriptase uses host cell mRNA as a primer for viral mRNA synthesis and to accomplish this the transcriptase steals the methylated cap region of RNA, this process is called cap snatching

mycobacteria tuberculosis epidemiology

***world's leading cause of death by an infectious agent - most common in SE asia, sub saharan africa, and E europe -very prevalent in immunosuppressed pt, drug or alcohol abusers, homelessness, individuals exposed to disease pt - humans are the only natural reservoir - person to person spread by infectious aerosols

H. influenzae tx and prevention

**100% mortality rate in untreated meningitis and epiglottitis tx: broad spectrum cephalosporins, amoxicillin with clavulanate p: Hib conjugate vaccine (polyribosyl ribitol phosphate

h. influenzae virulence factors

-capsule: **polyribosyl ribitol phosphate capsule, 6 antigenically serotypes but **B is the most important - IgA protease: cleaves IgA on mucous membranes - adherence: pili and other structures - LPS/ lipopolysaccharide: paralyzes cilia

erythema nodosum

(desert rash) - red tender nodules on extensor surfaces such as shins - delayed type hypersensitivity response to fungal ag - no organisms in nodules - not a sign of disseminated disease... good prognosis - seen in other granulomatous disease: histoplasmosis, tuberculosis, leprosy

atypical pneumonia

** most common cause: mycoplasma pneumoniae (other causes are chlamydophila pneumoniae, legionella pneumoniae), first identified after the introduction of penicillin (cases that did not respond to penicillin), gradual onset, nonproductive paroxysmal cough, mucoid sputum, low grade fever, well appearing facies, pleurisy and consolidation both rare, CXR shows nondefined infiltrate or interstitial pneumonia, gram stained sputum show predominance of mononuclear cells

pharyngitis and tonsillitis EBV pathogenesis and immunity

****EBV in saliva initiates infection of oral epithelia and tonsillar B cells and the virus is spread in B cells in lymphatic tissue and blood, EBV proteins replace host cell factors that normally activate B cell growth and development, B cell activation and proliferation occur and are indicated by presence of heterophile Ab *** B cell outgrowth is controlled by normal T cell response to B cell proliferation and EBV antigenic peptides, B cells present EBV Ag on both MHC I and II molecules to activate T cells, activated T cells appear as atypical lymphocytes/ downey cells

pharyngitis and tonsillitis CMV pathogenesis and immunity

**CMV is acquired from blood, tissues and most body secretions, it is spread through the body within infected cells such as lymphocytes and leukocytes, **CMV is reactivated by immunosuppression and allogeneic stimulation ***CMV prevents Ag presentation to both CD8 and CD4 T cells by preventing the expression of MHC I and II and the virus blocks NK cell attack of CMV infected cells and encodes an analog of IL10 that inhibits Th1 protective immune response

general characteristics of mycobacteria

**acid fast, weakly gram +, nonmotile, slender bacilli, nonspore forming, cell wall has high lipid content/ mycolic acid, requires complex media, strictly aerobic, slow growers

typical pneumonia

**most common cause: strep pneumoniae, acute onset (24-48 hrs), left over or concurrent URI ssx, productive cough with purulent sputum, high fever, shaking chills, dyspnea, pleuritic chest pain, tachycardia, toxic facies, consolidation in lungs on X ray (lobar pneumonia), gram stained sputum notable for neutrophil predominance, divided into CAP and HAP

histoplasma capsulatum clinical presentation

- ****symptomatic disease occurs in only 1% infected: fever, cough, chest pain, fatigue - 80% of ppl in ohio valley have evidence of infection by 18YO - reactivation can occur as a consequence of immunosuppression that results in reduced cellular immunity - severe disease: --chronic pulmonary disease: most often in men and usually a reactivation process which is precipitated by pulmonary damage, **Mediastinal fibrosis can result, leading to compromise of airways and vessels --severe dissemination is rare but occurs in infants and AIDS pt: mucocutaneous lesions (tongue) and hepatosplenomegaly --risk factors: extremes of age, transplant pt, immunosuppressive meds (steroids, TNF alpha inhibitors, methotrexate)

blastomyces dermatitidis clinical presentation

- ***severity of ssx depends on degree of exposure and immune status: most severe manifestation in immunocompromised pts typically involve CNS and has poor prognosis - acute pulmonary blastomycosis: pt either asymptomatic or may have only mild fever and cough -chronic pulmonary blastomycosis: ***may resemble TB or lung cancer radiographically - disseminated blastomycosis from lung infection: ***cutaneous skin lesions are most common manifestation of disseminated disease, other sites include bone, GU and brain

s. aureus pneumonia

- 3 main types --aspiration pneumonia: aspiration of oral secretions, seen in very young and very old, ** generally indistinguishable from other causes of aspiration pneumonia except s. aureus commonly causes more lung abscesses due to the toxins it produces -- hematogenous pneumonia: hematogenous spread from distant site of infection, s. aureus is a common cause of bacteremia that mostly arises from skin infections --necrotizing pneumonia: caused by community acquired MRSA, hemoptysis, septic shock, and high mortality rate, more common in children and young adults - a major cause of empyema occuring as a result of pneumonia

legionnaire's disease

- 3 major patterns: 1. sporadic cases that are community acquired, 2. epidemic outbreaks usually from air conditioners, 3. nosocomial infections in immunocompromised via respiratory equipment and aerosols - one of the top four pathogens in CAP, others are strep pneumoniae, mycoplasma pneumonia, and chlamydia pneumonia -ssx: primary manifestation is pneumonia: nonproductive cough, fever, headache, and myalgia; progressing to blood or purulent sputum, rales/ crackles, difficulty breathing, shaking chills -dissemination via circulatory system can occur: invades kidneys, liver, heart, CNS, and lymphatic system

HIV infection and mycobacterium

- HIV pt are prone to mycobacterium infection due to low cell mediated immunity - m. avium complex (MAC) and TB are most common bacterial infections in AIDS pt: can cause fatal fulminating miliary disease, large numbers of organisms in blood, stool and urine, MAC more resistant to common anti TB drugs - MAC can cause disease in immunocompetent host as well: in mid age or older men with hx of smoking or with underlying pulmonary disease, elderly female nonsmokers (lady windermere syndrome), solitary pulmonary nodules (cancer suspect)

spectrum of diseases caused by aspergillus species **

- allergic rxn: nasal cavity, paranasal sinuses, LRT - colonization: obstructed paranasal sinuses, bronchi, preformed pulmonary cavities - superficial cutaneous infections - limited invasive infections: bronchi, pulmonary parenchyma, mildly immunodeficient pts - invasive pulmonary infection: severely immunocompromised pts, systemic dissemination, death

SARS and MERS pathogenesis

- are cytolytic viruses that can replicate at 37C in epithelial cells, lymphocytes, and leukocytes; both cause systemic disease, incubation period b/n 2-7 days with 10 days max - the glycoprotein corona helps these viruses survive the GI tract - a combo of viral pathogenesis and immunopathogenesis causes significant lung, kidney, liver, and GI tissue damage and depletion of immune cells

SARS clinical syndromes

- atypical pneumonia characterized by: high fever, chills, rigors, headache, dizziness, malaise, myalgia, cough, difficulty breathing - syndromes lead to acute respiratory distress syndrome - ~20% of pt will also develop diarrhea

virulence factors of bacteria that cause pneumonia

- capsules: prevent phagocytosis in strep pneumoniae and h influenzae - rapid invasion of host cells before phagocytosis can occur: viruses and intracellular bacteria such as chlamydia - survival inside phagocytes: mycobacterium tuberculosis - survival of microbe leads to tissue injury, which leads to inflammation, which leads to increased vascular permeability, which leads to pneumonia: abscesses occur in some infections as the immune system begins to wall of pathogens

coccidioidomycosis

- caused by coccidioides immitis or c. posadasii - ***AKA coccidioidal granuloma, valley fever, san joaquin valley fever - ***causes a wide variety of lesions: the great imitator - lives in alkaline soils in **semiarid hot climates: US in sonoran desert in AZ and san joaquin valley in CA... but also in SW US , mexico

m. tuberculosis tx

- combo therapy, minimum of 6 mon, isoniazid, ethambutol, pyrazinamide, rifampin for 2 months then followed by 4-6 mon of isoniazid and rifampin - prophylaxis: isoniazid or rifampin - tx failures: pt non compliant, drug resistant -****MDR-TB (multidrug resistant TB): resistant to isoniazid and rifampin, 2nd gen aminoglycosides and fluoroquinolones, pyrazinamide, ethambutol -****XDR-TB (extensively drug resistant TB): tx is combo of several drugs for up to 2 yrs

diagnostic categories of pneumonia

- criteria based on: clinical setting, presentation of illness, exposure to particular pathogens, age and immune status of host - necessary because of wide range of pathogens that can be the cause - typically empirical therapy is necessary before a definitive dx can be made

adenovirus epidemiolgy

- disease/ viral factors: naked capsid virus is resistant to inactivation by the GI tract, drying, and detergents; disease ssx may resemble those of other respiratory virus infections, virus may cause asymptomatic shedding - transmission: direct contact, respiratory droplets, fecal matter on hands and fomites, inadequately chlorinated swimming pools and ponds -who at risk: children <14, people in crowded area - virus found worldwide with no seasonal incidence - modes of control: live vaccine serotypes 4 and 7 available for military use

virulence factors of b. pertussis

- filamentous hemagglutinin: required for binding to sulfated glycoprotein on membranes of ciliated cells in trachea - pertussis toxin: bind to glycolipid on surface of respiratory cells and ganglioside on surface of phagocytic cells

enterics in pneumonia

- gram - aerobic rods (klebsiella, e. coli, pseudomonas) - common cause of both community acquired and nosocomial typical pneumonia - often the cause of lung abscesses and necrosis - k. pneumoniae: upper lobar consolidation with bulging fissure sign (see image) - empiric therapy is often warranted, generally involving carbapenems or 4th gen penicillins

RSV epidemiology

- incubation 4-5 days - highly contagious: contagious period precedes ssx and may occur in the absence of ssx - transmission via inhalation of aerosols or contact with virus contaminated hands and fomites - is ubiquitous and found worldwide but incidence is seasonal - whos is at risk: -- infants: LRI, pneumonia, bronchiolitis --premature neonates: serious disease --children: spectrum of disease from mild to pneumonia -- adults: reinfection with milder ssx -- elderly adults: serious disease -- immunocompromised, chronic heart and lung problems: serious disease -modes of control: palivizumab for infants and children at high risk, aerosol ribavirin for infants and children with serious illness

parainfluenza virus pathogenesis and immunity

- infection only occurs in respiratory tract, URI most common but significant disease may also occur in LRT - viruses do not cause viremia or become systemic - the cell mediated immune response causes both cell damage and confers protection: IgA responses are protective but short lived, the viruses manipulate cell mediated immunity to limit the development of immune memory

influenza virus pathogenesis and immunity

- infects URT and LRT -local ssx result from epithelial cell damage including ciliated and mucus secreting cells -systemic ssx are caused by interferon and cytokine response to virus - interferon and cell mediated immune response (NK and T cells) are important for immune resolution and immunopathogenesis - infected people are predisposed to bacterial superinfection because of the loss of natural barriers and exposure of binding sites on epithelial cells - ab against HA and NA proteins are important for future protection against infection

histoplasma capsulatum pathogenesis

- inhaled conidia ingested by macrophages and develop into *** small oval budding yeast - ***facultative intracellular yeast proliferate w/in phagosome: produce alkaline substances that increase pH - organism spreads through body, esp liver and spleen: phagocytes can be found throughout the RES with histo, small granulomatous foci healed by calcifications, ***erythema nodosum may occur - with intense exposure pneumonia may develop

coccidioides immitis clinical forms

- initial pulmonary infection: fever, malaise, dry cough, joint pains, and sometimes rash/ **erythema nodosum; ***In endemic areas causes up to 29% of CAP, infection leads to lifelong immunity - chronic pulmonary coccidioidomycosis: symptomatic disease for > 6 wks leads to cavitary disease, risk factors include age, diabetes, smoking, low socioeconomic status

other types of pneumonia

- interstitial/ atypical: most common agent is mycoplasma pneumonia - chronic: most common agent is mycobacterium tuberculosis, shows up over weeks to month or more, hx of night sweats, significant weight loss, productive cough with purulent sputum, dyspnea - aspiration: similar to acute onset pneumonia, recurrent chills, foul smelling sputum, consolidations, in dependent lung segments, typically there is predisposing conditions (alcoholism, seizures, anesthesia, esophageal disorders), most common agents are oral anaerobes, assorted gram - enterics

parainfluenza virus clinical syndromes

- mild coldlike URI: coryza, pharyngitis, mild bronchitis, wheezing, fever - bronchiolitis -pneumonia - in children b/n 6 mon to 6 YO: bronchiolitis, pneumonia, croup croup in children: subglottal swelling that may close the airway, results in hoarseness, a seal bark cough, tachypnea, tachycardia, and suprasternal retraction that develop after 2-6 day incubation period, most children recover w/in 48 hrs, principal ddx is epiglottitis caused by h. influenzae type b

extrapulmonary TB

- miliary TB: spread of bacteria from lungs to bloodstream, disseminates to other organs (spleen, liver, bone marrow, kidney, adrenal gland, eyes), occurs most often in children, also in HIV pt - GU TB: UTI like symptoms with **sterile pyuria - skeletal TB (pott's disease): back pain and involvement of hip and knee

aspergillosis clinical presentation

- mode of infection: inhalation of conidia and inhaled conidia bind to fibrinogen and laminin in alveolus then conidia germinate and hyphal forms secrete proteases, colonization and invasion of skin also possible - cornea, external ear, paranasal sinuses: **** most common cause of fungal sinusitis - lungs: *** aspergilloma (fungus ball), grows especially in cavities from previous TB infection - allergic bronchopulmonary aspergillosis/ ABPA: asthmatic ssx and high IgE titer against aspergillus ag, expectorate brownish bronchial plugs containing hyphae

pathogenesis of pneumonia

- no resident bacteria in LRT - important defenses: alveolar macs, IgG in fluid lining the alveoli - no specific ab... macs have receptors for C reactive protein, complement or PAMPs - phagocytosis of invaders stimulates B and T cell activity via Ag presentation - stimulation of inflammation: infiltration by PMN leukocytes

penicilliosis

- penicillium marneffei: *** only spp of penicillium that is pathogenic dimorphic fungus, **produces diffusible red pigment in culture - immunocompromised pt infected in SE asia and china - ***pulmonary involvement: can mimic TB and other systemic fungal disease - **hematogenous dissemination can lead to development of cutaneous or subcutaneous papules, pustules, or rashes, which are often located on face

toxins of b. pertussis

- pertussis toxin: inactivates G1alpha, the membrane surface protein that controls adenylate cyclase activity, uncontrolled expression leads to increased cAMP, toxin inhibits phagocytic killing and monocyte migration - tracheal cytotoxin: peptidoglycan fragments that kills ciliated respiratory cells and stimulates the release of interleukin 1 (fever)

pneumocystosis

- pneumocystis jirovecii - recently reclassified as fungus rather than protozoan - cell wall is thin but glucan and chitin elements are present - rRNA and mitochondrial gene sequence are more homologous with fungi - however: no ergosterol but has cholesterol in cell membrane, does no grow on fungal media, ***does not respond to antifungal drugs - elliptical spores in sporocyte form spore case

systemic/ deep mycoses

- primary systemic pathogens: able to cause disease in healthy and immunocompromised pt, most infections are initiated in lungs following inhalation of conidia, have a propensity to invade the deep viscera after dissemination - caused by thermally dimorphic fungi -***typically endemic: geographically restricted to specific area - not normally transmitted among humans/ animals - ***immunity is cell mediated

mycobacterium

- range from strict pathogens to soil and water saprophytes - disease caused by mycobacterium --m. tuberculosis: TB -- m. leprae: leprosy -- other: nontuberculous mycobacteria (NTM), mycobacteria other than TB (MOTT), or atypical mycobacteria

complications of b. pertussis

- resp tract complications: secondary bacterial pneumonia which is the leading cause of pertussis related death and is provoked by damage to ciliated epithelium; pulmonary HTN - seizures and encephalopathy are complications of hypoxia from apnea - pressure effects from paroxysmal coughing can produce subconjunctival hemorrhage, epistaxis, subdural hematoma, pneumothorax

hantavirus pulmonary syndrome pathogenesis and epidemiology

- sin nombre virus is transmitted in aerosols from deer mice urine and close contact with infected deer mice, **virus initiates infection and remains in lung where it causes hemorrhagic tissue destruction and lethal pulmonary disease

legionella epidemiology

- sources of infections: environmental water sources, air conditioning systems, cooling towers, fountains, and other water sources that produce aerosols, can survive in chlorinated water - usually transmitted by aerosols -***intracellular parasite of free living protozoa and alveolar macrophages and epithelial

paracoccidioides clinical presentation

- spores are inhaled - most primary infections are asymptomatic - early lesions occur in lungs - organisms may become dormant - chronic granulomatous dissemination can occur: oral lesions, enlarged lymph nodes

influenza epidemiology

- strains of influenza A are classified by: type A, place of original isolation, date of original isolation, HA and NA type - strains of influenza B are classified by: type B, geography, date of isolation, does not mention HA or NA antigens because they do not undergo antigenic shift - transmission: virus transmission precedes ssx, spread by inhalation of small aerosol droplets expelled during talking, breathing, and coughing, likes cool and less humid environment, extensively spread by school age children - who is at risk: seronegative ppl, adults get classic flu syndrome, children get asymptomatic to severe respiratory tract infection, high risk groups are elderly and immunocompromised pt and ppl in nursing homes or with underlying cardiac or respiratory problems (including asthma and smokers) -geography/ season: worldwide occurrence, epidemics are loca and pandemics are worldwide, more common in winter - modes of control: amantadine, rimantadine, zanamivir, oseltamivir are approved from prophylaxis or early tx, killed and live vaccines predicted yearly strains of influenza A and B viruses

infectious mononucleosis dx***

- symptom based: triad of lymphadenopathy, splenomegaly, exudative pharyngitis - CBC: atypical lymphocytes (T cells, downey cells) - heterophile Ab (transient) - EBV ag specific Ab -viral DNA

TNF alpha inhibitors

- tx for rheumatoid arthritis, inflammatory bowel disease - these pt are significant risk for infection with endemic fungi esp histoplasma capsulatum, and when infected tend to develop severe disseminated infection

aspergillus spp

- ubiquitous airborne soil fungus: soil, plants, water, pepper, air - hundreds of spp - most important spp: a. fumigatus, a flavus, a. niger, a. terreus

pneumocystis jirovecii

- unicellular fungus that causes pneumocystis pneumonia/ PCP** - ** not associated with disease in healthy individuals - most prominent OI in AIDS pt - pneumonia forms secretions in lungs that block breathing and be rapidly fatal if not controlled: ***interstitial pneumonitis with mononuclear infiltrate, nonproductive cough, dyspnea, cyanosis, CXR shows ** perihilar ground glass appearance, extrapulmonary lesions seen in AIDS pt

gen characteristics of pseudomonas

-** do not ferment sugars: produce acid form glucose or other carbohydrates in presence of oxygen/ oxidization, ability to use variety of sugars is diagnostic -** oxidase positive: **produce cytochrome c oxidase -minimal nutritional needs: can grow in water containing traces of nutrients

coccidioidomycosis in AIDS

-****Coccidioidomycosis is an AIDS-defining clinical condition -Disseminated disease should be considered in AIDS patients in all areas of the US -Patients often present with a rapidly fatal disseminated disease -Blood cultures are often positive for C. immitis

coccidioides pathogenesis

-****Most virulent of all human mycotic pathogens - inhaled arthroconidia reach alveoli --> convert to spherule that gives rise to endospores --> endospores phagocytized but survive --> large spherules escape phagocytosis - proteases and spherule outer wall may be linked to virulence - percutaneous inoculation is rare, from cat bite - seen after earthquakes, and windstorms, from soil being turned up image shows spherule

disseminated coccidioidomycosis

-***most commonly develops in pts with AIDS or defects in cell mediated immunity: meningitis, infections of bones and joints, GU tract, cutaneous, ophthalamic - risk factors: male, filipinos, AIDS, immunosuppression, pregnancy in 3rd trimester - mortality is over 80% if untx - CNS involvement worsens the outcome

common cold facts

-***purulent discharge often associated with late stages of cold is not due to direct effects of virus but rather bacterial superinfection - true colds are very minor in and of themselves with regard to pt health but they are responsible for huge labor hours lost and therefore economic losses

adenovirus clinical syndromes

-**acute febrile pharyngitis: typically occurs in children < 3YO - **pharyngoconjunctival fever: pharyngitis accompanied by conjunctivitis, typically occurs in outbreaks involving older children - ssx: mild flulike ssx, nasal congestion, cough, coryza, malaise, fever, chills, myalgia, headache - **symblepharon: adhesion fro lid to eyeball after conjunctivitis - **follicular conjunctivitis: condition in which the mucosa of palpebral conjunctiva becomes pebbled or nodular, and both conjunctivae become inflamed - **epidemic keratoconjunctivitis: irritation of eye by a foreign body or debris, this irritation is a risk factor for adenovirus infection, typically an occupational hazard for industrial workers -** acute respiratory disease: high incidence among the military, ssx: fever, runny nose, cough, pharyngitis, possible conjunctivitis - other: cold like ssx, laryngitis, croup, bronchiolitis, pertussis like illness in children and adults -**gastroenteritis and diarrhea: enteric adenoviruses, major cause of viral gastroenteritis in infants - **systemic infection in immunocompromised pts: pneumonia, hepatitis - other: intussusception in young children, acute hemorrhagic cystitis with dysuria and hematuria in young boys, MS disorders, genital and skin infections, obesity

influenza tx

-**amantadine and rimantidine target M2 protein and inhibit the uncoating step of influenza A only - **zanamivir and oseltamivir inhibit the neuraminidase of influenza A and B, without neuraminidase the HA binds sialic acid on other glycoproteins and viral particles clump thereby preventing virus release, **effective for prophylaxis and for tx during the first 24-48 hrs after onset of illness, tx does not prevent later host induced immunopathogenic stages of disease

coccidioides immitis

-**dimorphic block like arthroconidia in the free living mold stage and spherules containing endospores in lungs

influenza virulence factors

-**hemagglutinin/ HA: viral attachment, binds to sialic acid on cell surface glycoproteins, promotes fusion of envelope to cell membrane, HA binds to RBCs, target for neutralizing ab, **undergoes antigenic drift and antigenic shift -**neuraminidase/ NA: cleaves sialic acid and promotes virion release from infected cells, target for antiviral drugs (** zanamivir/relenza and oseltamivir/ tamiflu), undergoes antigenic shift - **matrix protein/ M1: promotes virion assembly - **membrane protein/ M2: forms a proton ion channel in membranes and promotes uncoating and viral release, the M2 is target for antiviral drugs (amantadine and rimantadine)

b. pertussis prevention

-DTP: whole cell vaccine - DTaP: replaced DTP -Tdap: booster vaccine is highly effective but immunity is not life long

legionella clinical infections

-aerosol transmission: ***person to person via aerosol transmission has not been documented, enter cells, prevents phagolysosome fusion, and multiply within host cells, disease has a large range from asymptomatic to fatal - **epidemiology suggests that asymptomatic infection with subsequent immunity is common -**predisposition for disease: immunocompromised, pts with chronic lung disease, alcoholic and heavy smokers

bordetella pertussis epidemiology

-aerosol transmission: bacterial adhere to and grow on ciliated respiratory epithelial cells - highly contagious: 90% of exposed get disease, immunity after infection is poor, adults can become transient carrier, ***babies less than 1 yr are most at risk for morbidity and mortality and the focus of prevention efforts

aspergillosis

-aspergillus fumigatus - **grows only as mold, not dimorphic - ***septate hyphae, V branches - radiating conidia - microscopic appearance is definitive identification

croup causes

-bacterial: m. pneumoniae - virus: parainfluenza virus, influenza virus, RSV

causes of pharyngitis/ laryngitis

-bacterial: s. pyogenes, m. catarrhalis, n. gonorhoeae -viral: common cold viruses, adenovirus, RSV

blastomycosis

-blastomyces dermatitidis - free living species in soil of large section of E US (ohio, MS, and st lawrence river, and great lakes) - moist soil rich in organic matter - higher incidence in males b/n 40-60 yo and rural farm workers

adenovirus pathogenesis and immunity

-capable of causing lytic and latent infections -infects mucoepithelial cells in the respiratory tract, GI tract, and conjunctiva or cornea causing cell damage directly - virus is spread in aerosols, in fecal matter, and by close contact, fingers spread virus to eyes -viremia may occur after local replication of virus, with subsequent spread to visceral organs, more likely to occur in immunocompromised pts - virus becomes latent and persists in lymphoid tissue, virus can be reactivated in immunosuppressed pts - ab and cell mediated immunity are important for resolving infection, ab to one serotype is not protective against another serotype

RSV pathogenesis and immunity

-causes localized infection of nasopharynx and lower respiratory tract, RSV induces syncytia - does not cause viremia or systemic spread - invades respiratory epithelium which leads to immune mediated cell injury - bronchi and bronchioles become necrotic resulting in the formation of plugs of mucus, fibrin, and necrotic material in the airways - the narrow airway of infants are obstructed by these plugs -maternal ab is not sufficient to protect from viral infection, natural infection does not prevent reinfection, vaccination with killed vaccine may enhance disease severity

CMV congenital and perinatal infections

-congenital: small size, thrombocytopenia, microcephaly, intracerebral calcification, jaundice, hepatosplenomegaly, rash, vision or hearing loss, mental retardation - perinatal: no disease in healthy full term infants, significant infection in premature infants

parainfluenza virus epidemiology

-contagion period precedes ssx and may occur in the absence of ssx, reinfection can occur and reinfection is milder - transmission via inhalation of aerosols or contact with people/ fomites - who is at risk: children at risk for mild disease or croup, adults at risk for reinfection with milder ssx - virus is ubiquitous and worldwide, incidence is seasonal - no vaccine available to prevent disease

legionella lab dx

-culture: BCYE, L cysteine requirement - detection of ag in urine: most diagnostic for l. pneumophila - direct fluorescent ab staining

sputum in regards to pneumonia

-difficult to collect: contamination from oropharyngeal flora, sputum versus spit - expectorated sputum: rinse mouth with water, expectorate with aid of a deep cough into sterile container - induced sputum: aerosol of solution that stimulates coughing - blood or bronchoalveolar lavage is usually much better for dx

c. diphtheriae virulence factor

-diphtheria toxin: produced by certain strains, lysogenized by bacteriophage with toxin gene (tox+), **only toxin producing bacteria can cause diphtheria, toxin is antigenic thus can use IgG to block toxin effects - A-B toxin fragments --A: active fragments: inhibits protein synthesis by inactivating elongation factor 2, leads to cell/tissue death --B: binds to specific cell membrane receptors, mediates entry of fragment A

hantavirus pulmonary syndrome dx

-early dx is difficult due to the ssx being fever, mm aches, fatigue - if pt has fever, fatigue, hx of potential rodent exposure, and SOB it is likely the pt has HPS - serology to confirm: ELISA for IgM and IgG - RT-PCR to detect viral RNA - immunohistochemistry stain post mortem for retrospective dx

factors affecting tuberculin skin test

-false positives: infection with non TB mycobacteria, BCG immunization (live attenuated mycobacterium bovis) - false negatives: anergy (no cell mediated immunity seen in HIV and AIDS), recent infection, younger than 6 months, overwhelming TB disease

bordetella pertussis labs

-gram stain: gram - coccobacillus - culture on charcoal blood agar with cephalexin: **regan lowe agar, ** mercury drop colonies - PCR dx can also be helpful

CMV dx

-histology and cytology: cytomegalic cells/ owl's eye - Ag and genome detection -cell culture -serology

histoplasmosis

-histoplasma capsulatum - most prevalent in eastern and central regions of US - grow in moist soil high in nitrogen content: enriched with bird/ bat poo, eastern half of US esp ohio and MS river valleys

metapneumovirus

-human metapneumovirus/ hMPV is newly ID virus in 2001, closely related to RSV - **hMPV accounts for up to 15% of common colds in children especially those complicated by otitis media: signs include cough, sore throat, runny nose, and high fever; nearly all 5YO children have been infected and are seropositive -** approx 10% of pts with hMPV experience wheezing, dyspnea, pneumonia, bronchitis, or bronchiolitis

influenza clinical time course

-incubation period 1-4 days: flu syndrome begins: malaise, headache, fever, chills, severe myalgias, loss of appetite, weakness and fatigue, sore throat, non productive cough - fever persists for 3-8 days - complete recovery within 7-10 days

blastomycosis pathogenesis

-inhaled conidia convert to yeast - localized yeast invasion of host invokes inflammatory rxn - yeast escapes recognition by macs and disseminates via bloodstream - dogs are 10x more likely to be infected than humans

bacterial LRIs in cystic fibrosis pts

-lung environment is different from other pathologic settings so different organisms: pseudomonas aeruginosa, s. aureus, h. influenzae non typable, pseudomonas cepacia -***by age 15-20 almost all CF pts have lungs colonized by p. aeruginosa

mycoplasma pneumonia DX

-microscopy and culture are both problematic --slow growth in lab, culture is not done by most labs -- microscopy is typically uninformative -- ***PCR or Ab detects are preferred test but both have problems -- *** cold agglutinin test are insensitive and nonspecific, cross reactive with EBV, CMV, adenovirus

s. pneumoniae dx

-microscopy and culture both highly sensitive: pneumococcus is highly sensitive to abx so cultures may be negative in pts already receiving abx - lab ID: alpha hemolytic, catalase negative, optochin susceptible, bile soluble

paracoccidioides

-mycelial phase in soil - yeast phase at 37C, has multiple buds attached - large, spherical thick walled with ***Multiple buds.. resembles ***mariner's wheel

RSV prevention and control

-palivizumab: anti RSV monoclonal ab, prophylactic and therapeutic passive immunization for young children at high risk for serious disease - isolate infected person and use infection control methods - no prophylactic RSV vaccine is available

paracoccidioidomycosis

-paracoccidioides brasiliensis: aka south american blastomycosis - source/ distribution: soil, endemic in rural latin america, disease occurs only in that region

m. tuberculosis clinical disease

-primary tuberculosis: transmitted by airborne droplet nuclei or by dust, infect the deep lung in the alveoli, bacteria get phagocytized and continue to multiply, usually mild or even asymptomatic, after 4-6 wks T cells sensitize and allow destruction of intracellular bacteria, regression and healing of primary lesion - positive tuberculin skin test: PPD -granulomas: characterized by nodular, caseous granulomas, **most pt with primary tuberculosis are asymptomatic, granulomas may resolve, reactivation can occur (advanced age, immunocompromised, malnutrition), **these lesions tend to appear in upper lobes of lung due to their increased oxygen content

s. pyogenes virulence factors

-streptolysin O: oxygen labile and only active under anaerobic conditions, destroys WBCs, platelets, RBCs, and other tissues; can use antistreptolysin O tests to check for Ab as evidence of recent exposure - streptolysin S: oxygen stable, can lyse RBCs and WBCs, responsible for hemolysis on surface of blood agar plate -streptodornases (DNase A-D): protects bacteria from being trapped in the neutrophil extracellular trap, help destroy DNA in exudates and necrotic tissue -hyaluronidase (spreading factor): break down of connective tissue -streptococcal pyrogenic exotoxins: erythrogenic toxins, many act as superantigens, manifests as necrotizing fasciitis, STSS, spreading rash of scarlet fever

adenovirus dx

-throat swab: detect the presence of adenovirus in pt with pharyngitis, lab test must eliminate other causes of pharyngitis such as strep pyrogenes - rapid detection of adenovirus in clinical samples: immunoassays, PCR -histologic analysis: histologic hallmark of adenovirus infection is a dense, central intranuclear inclusion that consists of viral DNA and protein within an infected epithelial cell, inclusions resemble those seen in CMV infection but w/o cytomegaly

h. influenzae infections/ clinical manifestations

-type B: meningitis, epiglottitis, bacteremia --** meningitis: in infants and children 3 mon to 6 YO, invasion of respiratory tract, bacteremia allows spread to meninges and CSF --**epiglottitis: affects children 2-4 YO, acute inflammation and swelling causing airway obstruction nontypable: otitis media, sinusitis, tracheobronchitis, pneumonia

metapneumovirus epidemiology

-viral infection may be asymptomatic, cause the common cold, or cause serious bronchiolitis and pneumonia; reinfection may occur - transmission via inhalation of aerosols or contact with infected hands or fomites -children, elderly adults, and immunocompromised are at risk - virus is ubiquitous and found worldwide, peak illness is in winter - modes of control: hand washing, disinfecting contaminated objects, no vaccine available

A 3-year-old male presents to the office with the complaint of a persistent non-productive cough. History reveals he is fully vaccinated and has no other past medical history. Vitals reveal a blood pressure of 110/70 mmHg, a heart rate of 100/min, a respiratory rate of 20/min, a temperature of 37°C (99.5°F), and an oxygen saturation of 99% on room air. Physical examination reveals a cough represented in the exhibit. The examination is remarkable for an erythematous oropharynx, and the lungs are clear to auscultation. 1. The most likely diagnosis is: a. Acute epiglottitis b. Bronchiolitis c. Laryngotracheobronchitis d. Pertussis e. Streptococcal pharyngitis 2. What is the radiographic finding associated with the most likely diagnosis? a. Lobar consolidation b. Lung hyperinflation c. Steeple sign d. Supraglottic narrowing e. Thumbprint sign 3. Which of the following describes the virus responsible for this disease? a. Enveloped capsid, dsDNA genome b. Enveloped capsid (-)ssRNA genome c. Naked capsid, dsDNA genome d. Naked capsid, (-)ssRNA genome e. Naked capsid, (+)ssRNA genome

1. c 2. c 3. b

A 9-month-old boy was born prematurely, requiring treatment in a neonatal intensive care unit for the first month of life. After discharge, he remained well until 3 days ago, when symptoms of a common cold progressed to cough, rapid and labored respiration, lethargy, and refusal to eat. On examination his temperature was 38.5°C, respiratory rate 60/min, and pulse 140/min. Auscultation of the chest revealed coarse crackles and occasional wheezes. Abnormal laboratory findings included hypoxemia and hypercarbia. A chest radiograph showed hyperinflation, interstitial perihilar infiltrates, and right upper lobe atelectasis. 1. What is the most likely etiologic agent responsible for causing the infant's symptoms? a. Rhinovirus b. Coronavirus c. Adenovirus d. Metapneumovirus e. Respiratory syncytial virus 3. Which of the following agents can be used to prevent RSV pneumonia? a. Amantadine b. Vaccine to F protein c. Oseltamivir d. Zanamivir e. Monoclonal antibody

1. e 2. e

ssx of 1. acute influenza infection in adults 2. acute influenza infection in children

1. rapid onset of fever, malaise, myalgia, sore throat, and nonproductive cough 2. acute disease similar to that in adults but with higher fever, GI tract ssx like abd pain and vomiting, otitis media, myositis, and more frequent croup

2 types of respiratory infections and give examples and consequences

1. restricted to surface: -common cold virus, influenza, strep throat, chlamydia, diptheria, pertussis, candida albicans/ thrush - local spread, local (mucosal) defense important, adaptive immune response sometimes too late to be important in recovery, short incubation period/ days 2. spread through body: - measles, mumps, rubella, EBV, CMV, chlamydophila psittaci, Q fever, cryptococcus - little or no lesions at site of entry, microbe spreads through body and returns to surface for final multiplication and shedding, adaptive immune response important in recovery, longer incubation period/ wks

sputum appearance and the most likely cause 1. purulent 2. mucoid 3. rust colored 4. green colored 5. thick, currant jelly, red 6. large amount of blood 7. foul smelling

1. typical pneumonia 2. interstitial pneumonia 3. strep pneumoniae 4. pseudomonas aeruginosa or H influenzae 5. klebsiella pneumoniae 6. cavitary tuberculosis or lung abscess 7. anaerobic bacterial pneumonia

anti- TB drugs

1st line: isoniazid, rifampin, pyrazinamide, ethambutol, rifabutin, rifapentine 2nd line: streptomycin, cycloserine, p aminosalicyclic acid, ethionamide, amikacin, capreomycin, fluoroquinolones

legionella pneumophila

2 manifestations of disease: legionnaire's disease/ legionellosis or pontiac fever slender gram - bacilli, aerobic, non spore forming, non encapsulated, **facultative intracellular, ** culture on buffered charcoal yeast extract agar/ BCYE (requirements for L cysteine constitutes a presumptive dx, ability to multiply at large range of temp and survives in temps up to 60C

rhinitis/ coronavirus family and virion

2nd most important cause of common cause coronaviridae virions are medium sized with solar corona like appearance, virion glycoproteins on envelope surface appear as club shaped projections (+) ssRNA genome enclosed in envelope containing the E2 viral attachment protein,, E1 matrix protein, and N nucleocapsid protein

adenovirus virion

7 subgroups for human adenovirus virions are naked icosadeltahedral capsids with fibers (viral attachment proteins) at vertices genome is linear double stranded DNA

mnemonic for corynebacterium diphtheriae

ABCDEFG ADP ribosylation Beta prophage Corynebacterium Diphtheriae Elongation Factor 2 Granules

mnemonic for epiglottitis

AIR RAID Airway inflammation causing obstruction Increased pulse Restlessness Retractions Anxiety increased Inspiratory stridor Drooling

CAP vs HAP

CAP: community acquired pneumonia, person to person, animal, or environmental exposure HAP: hospital acquired pneumonia, tends to be caused by gram - bacteria, usually in association with assisted ventilation

pharyngitis and tonsillitis mumps virus epidemiology

Disease/Viral Factors Contagion period precedes symptoms (virus is spread in respiratory symptoms from asymptomatic patients during the 7-day period before clinical illness) Immunity is lifelong. Transmission Inhalation of aerosols. Who is at risk? Unvaccinated people Immunocompromised people, who have more serious outcomes

pharyngitis and tonsillitis CMV epidemiology

Disease/Viral factors Virus causes lifelong infection. Recurrent disease is a source of contagion. Virus causes asymptomatic shedding. Transmission Occurs via blood, organ transplants, and all secretions (urine, saliva, semen, cervical secretions, breast milk, and tears). Virus is transmitted orally and sexually, in blood transfusions, in tissue transplants, in utero, at birth, and by nursing Who is at risk? Babies (especially babies of mothers who seroconvert while pregnant) Sexually active people Blood and organ recipients Burn victims Immunocompromised people: symptomatic and recurrent disease

persons at high risk for secondary TB

HIV infection, substance abuse esp IV, recent infection, diabetes, cancer, renal disease, those undergoing immunosuppression therapy, low body weight, hx of inadequately tx TB

mumps virus pathogenesis and immunity

Mumps virus causes acute, benign viral parotitis (painful swelling of the salivary glands). The virus infects the epithelial cells of the respiratory tract and is spread systemically by viremia. Principal symptom is swelling of the parotid and other glands caused by inflammation. Cell-mediated immunity is essential for control but also leads to symptoms. Humoral immunity is not sufficient to control infection because the virus spreads cell-to-cell. Immunity is lifelong.

most common cause of LRI in infants

RSV, influenza virus

general viral respiratory infections

RSV, metapneumovirus, parainfluenza virus, coronavirus (SARS, MERS), influenza virus, adenovirus, hantavirus

influenza prevention and control

VACCINATION recommended for everyone especially: ppl over 50 YO, healthcare workers, pregnant women who will be in their 2nd or 3rd trimester during flu season, ppl living in nursing homes, ppl with chronic pulmonary heart disease, ppl with asthma - inactivated subunit vaccines is a mix of extracts of purified HA and NA proteins from 3/4 different strains of virus -killed whole virus vaccines -live attenuated influenza vaccine via nasal spray consists of reassortment viruses that contain HA and NA gene segments of selected influenza strains -**persons with serious allergies to eggs can get the recombinant of tissue culture generated vaccines or the live vaccine

mycoplasma pneumoniae

causes primary atypical pneumonia/ walking pneumonia, smallest free living bacteria, no cell wall, pleomorphic, **naturally resistant to all abx that inhibit cell wall synthesis, cell membrane contains sterols, infection spread by close contact via aerosols during coughing episodes

c. diphtheriae clinical disease

_*** respiratory diphtheria: sudden onset with exudative pharyngitis, sore throat, low grade fever, and malaise; sudden severe prostration, a thick pseudomembrane develops over the pharynx, in critically ill pts must watch for breathing obstruction, cardiac arrhythmia, coma, and death - systemic effects: toxin is absorbed in bloodstream and carried systemically, affects the kidneys, heart, and nervous system that will sometimes cause demyelinating peripheral neuritis resulting in paralysis; death occurs due to cardiac failure

pontiac fever

_***nonpneumonic form of legionellosi - self limiting febrile illness: flulike ssx, fever, headache, myalgia, lasting 2-5 days -spontaneous recovery: does not generally lead to mortality -pathogenesis is thought to bome from hypersensitivity to the bacterial endotoxin

A 2-month-old infant developed a respiratory illness that the pediatrician diagnosed as bronchiolitis. The most likely cause of the disease is a. Respiratory syncytial virus b. Parainfluenza virus type 4 c. Influenza virus d. Metapneumovirus e. Rhinovirus

a. RSV

symblepharon

adhesion from lid to eyeball after conjunctivitis in adenovirus

penicilliosis tx

amphotericin B followed by itraconazole w/o tx mortality has exceeded 90%

steeple sign on Xray

appearance of tapering of upper trachea on a frontal CXR resembles a church steeple, this sign supports the dx of croup typically caused by paramyxovirus/ parainfluenza virus

most common cause of LRI in 3 mon olds to teens

assorted viruses, s. aureus, mycoplasma pneuoniae

A 32-year-old male physician developed a "flulike" syndrome with fever, sore throat, headache, and myalgia. To provide laboratory confirmation of influenza, a culture for the virus was ordered. Which of the following would be the best specimen for isolating the virus responsible for this infection? a. Stool b. Nasopharyngeal swab c. Vesicle fluid d. Blood e. Saliva

b

A 57-year-old Caucasian male presents with his wife to your office for a routine primary care visit. He is without complaints and review of his symptoms is negative. His medical history includes chronic obstructive pulmonary disease, hypertension and hyperlipidemia. He has a 15-pack-year history of tobacco abuse but quit over two years ago. He denies a history of alcohol abuse or illegal drugs. He is compliant with his medications and stable on inhaled albuterol as needed and amlodipine. Vital signs reveal a temperature of 98.6°F, blood pressure 126/82 mm Hg, heart rate of 76 bpm, and a respiratory rate of 15. Physical examination is remarkable for a slightly overweight male in no acute distress. On review of his records he received the influenza vaccination one year ago with no adverse events. He denies recent emergency room visits and has never been hospitalized. He is also up to date on his colonoscopy screening. Which of the following is the most appropriate immunization at this time? a. Pneumococcal vaccination only b. Trivalent influenza and pneumococcal vaccinations c. Trivalent influenza vaccination only d. Trivalent intranasal influenza and pneumococcal vaccinations e. Trivalent intranasal influenza vaccination only

b

A 70-year-old nursing home patient refused the influenza vaccine and subsequently developed influenza. She died of acute pneumonia 1 week after contracting the flu. The most common cause of acute post-influenza pneumonia is which of the following? a. Legionella b. Staphylococcus aureus c. Measles d. Cytomegalovirus e. Listeria

b

elek test

based on toxin/ antitoxin precipitation

A 2-year-old boy presents to the emergency department because of a sore throat, fever, hoarseness, and stridor. The physician suspects a diagnosis of croup, but wishes to exclude epiglottitis. Compared with croup, which of the following is characteristic of epiglottitis? a. Epiglottitis is associated with inflammation of the larynx and subglottic trachea. b. Epiglottitis is associated with rhinorrhea and conjunctivitis. c. Epiglottitis often leads to respiratory distress. d. Symptom onset is gradual in epiglottitis. e. The barking cough of epiglottitis becomes inspiratory stridor. f. Throat swab in epiglottitis would reveal parainfluenza virus.

c. Epiglottitis often leads to respiratory distress.

SARS coronavirus shares some characteristics, but not all, with human coronavirus HCoV-OC43. Which of the following statements is true for SARS coronavirus? a. Causes annual outbreaks during the winter b. Is distributed worldwide c. Populations at high risk of disease included health care workers d. Natural hosts are palm civets

c. Populations at high risk of disease included health care workers

pneumonia in children vs adults

c: mainly viral or bacterial secondary to viral, more often viral, neonates may develop interstitial pneumonitis caused by chlamydia trachomatis acquired from mother at birth a: bacteria more common, etiology varies with age, underlying disease, occupational and geographic risk factors

EBV nasopharyngeal carcinoma

cancer endemic to china and south east asia, EBV is likely a cofactor of disease with ingested nitrosamines (carcinogen) from preserved fish, tumor cells are of epithelial origin

m. tuberculosis virulence

capable of intracellular growth in alveolar macs, disease primarily from host response to infection

SARS/ severe acute respiratory syndrome

caused by coronavirus the glycoprotein helps enveloped virus survive in GI tract the animal coronavirus that causes SARS can replicate at 37C and cause systemic disease which is exacerbated by inflammatory responses

influenza dx

cell culture, hemadsorption to infected cells to detect presence of HA, hemagglutination in presence of virus in secretions, hemagglutination inhibition determine type and strain, ab inhibition of hemadsorption identification of type and strain, immunofluorescence, ELISA, serology, RT-PCR

most common cause of LRI in neonates

chlamydia trachomatis

pathogenesis of granuloma formation

chronic infection with inflammation occurs when microbes are resistant to the microbicidal effects of activated macs, persistent Ag activates a DTH response, the granuloma serves to wall of pathogen and limit the spread

lancefield classification

classifies strep place strep into dilute acid solution, soluble ag used to immunize rabbits, developed Ab to the C antigen classified several different carbohydrate group antigens: A-U strep in lancefield groups are more virulent and have more virulence factors than non lancefield strep: pyogenic strep

follicular conjunctivitis

condition in which the mucosa of palpebral conjunctiva becomes pebbled or nodular, and both conjunctivae become inflamed

SARS and MERS are in what family

coronavirus

causes of pharyngitis and tonsillitis

coxsackie A virus EBV CMV epidemic parotitis/ mumps virus

Each of the following statements concerning the antigenicity of influenza A virus is correct EXCEPT: a. Antigenic shifts, which represent major changes in antigenicity, occur infrequently and are due to the reassortment of segments of the viral genome. b. Antigenic shifts affect both the hemagglutinin and neuraminidase. c. The worldwide epidemics caused by influenza A virus are due to antigenic shifts. d. The protein involved in antigenic drift is primarily the internal ribonucleoprotein.

d

Your patient is a 75-year-old woman with fever, chills, and myalgia that began yesterday. It is January and an outbreak of influenza is occurring in the retirement community in which she lives. A rapid test for influenza antigen is positive. Which one of the following is the best choice of drug to treat the infection? a. Acyclovir b. Amantadine c. Interferon d. Oseltamivir e. Ribavirin

d

Coronavirus infections in humans usually cause a common cold syndrome. However, a recent outbreak of SARS was characterized by pneumonia and progressive respiratory failure. The prevention or treatment of these diseases can be accomplished by a. A subunit vaccine b. A cold adapted live-attenuated vaccine c. The antiviral drug amantadine d. Infection control measures, including isolation and wearing of protective gear e. The antiviral drug acyclovir

d infection control measures

rhinitis/ rhinovirus clinical syndrome

indistinguishable from other causes of rhinitis ssx: sneezing, rhinorrhea, nasal obstruction, headache, malaise, low grade fever peak at 3-4 days cough and nasal ssx may persist 7-10 days or longer

pharyngitis and tonsillitis coxsackie A virus pathogenesis and immunity

does not usually cause enteric disease, virus replicates within and is transmitted via fecal oral route, virus enters through mouth and URT, viral replication initiates in mucosa and lymphoid tissues of tonsils and pharynx, viral pathologic effects are responsible for disease Ab provide protective immune response

hand foot and mouth disease

due to coxsackie A virus ssx: vesicular exanthem (rash) and/or lesions on hands, feet, mouth, and tongue; mild fever, illness subsides in few days

pharyngitis and tonsillitis coxsackie A virus dx and tx

dx: ID herpangina, throat culture, RT-PCR to detect enterovirus tx: supportive and symptomatic care

blastomycosis dx and tx

dx: KOH and biopsy show ***Large spherical broad based budding yeast, use appropriate specimens, culture can be helpful but requires 4 or more wks tx: itraconazole for mild to moderate disease, amphotericin B for more serious or disseminated disease, itraconazole for long term prophylaxis in immunocompromised pts

coccidioidomycosis dx and tx

dx: KOH or calcofluor white stain to identify spherules/ endospores in sputum, exudate from cutaneous lesions, spinal fluid, blood, urine, and tissue biopsies, culture, serology-EIA ab titer, urine ag tx: itraconazole to limit ssx, severe disease requires tx with amphotericin B followed by an azole for at least 1 yr and fluconazole for meningitis

aspergillus dx and tx

dx: KOH or direct prep and see septate, branching hyphae; may seen conidia in sputum; culture shows rapid growing white colony turning colors depending on species tx: amphotericin B or voriconazole, surgical removal of fungus ball

SARS dx, tx, prevention/control

dx: RT-PCR to detect viral RNA genome in respiratory and stool sample, virus isolation requires BSL-3 conditions tx: no vaccine or antiviral tx available, ribavirin p/c: strict quarantine for infected individuals, screen for fever in travelers from a region within the outbreak zone

RSV dx and tx

dx: RT-PCR to detect viral genome in throat swab specimens and nasal washings, immunofluorescence and enzyme immunoassay tests for detection of viral ag tx: in otherwise healthy infants tx is supportive, for severe disease use aerosolized ribavirin

metapneumovirus dx and tx

dx: lab dx is usually unnecessary, RT-PCR to detect pneumoviruses and distninguish them from other resp disease viruses tx: supportive care

histoplasmosis dx and tx

dx: microscopy, culture, serology with complement fixation and immunodiffusion, urine ag test tx: for pulmonary and disseminated use amphotericin B followed by itraconazole

rhinitis/ coronavirus dx and tx

dx: primarily by clinical syndrome tx: OTC meds

rhinitis/ rhinovirus dx and tx

dx: primarily by clinical syndromes tx: OTC meds, inhalation of hot humidified air to increase drainage

parainfluenza dx, tx, prevention/ control

dx: real time PCR to detect parainflunzae RNA in throat swabs, immunofluorescence to detect presence of syncytia in respiratory aspirates or in cell culture tx: -for croup: nebulized cold or hot steam, monitor airway, on rare occasions intubation may be needed - ribavirin may be given for severe viral infections and immunocompromised p/c: no antiviral agents or vaccines are available

pneumocystosis dx and tx

dx; *** CXR shows ground glass appearance extending from hilar region, alveoli filled with ***foamy exudate, **stain bronchoalveolar lavage sample with methenamine silver, direct fluorescent ab, rapid stain tx: ***trimethoprim- sulfamethoxazole/ TMP-SMX is tx of choice for all forms of pneumocystosis

Which of the following conditions is LEAST likely to be caused by adenoviruses? a. Conjuctivitis b. Pneumonia c. Hepatitis d. Pharyngitis e. Glomerulonephritis

e

most common causative agent of LRI in pt with nursing home resident with underlying cardiopulmonary disease, recent abx therapy, or multiple medical comorbidities

enteric gram - bacteria such as e. coli, k. pneumoniae, enterobacter

influenza/ orthomyxoviruses virion

enveloped and have a segmented negative sense RNA genome, segmented genome facilitates the development of new strains through mutation and reassortment of gene segments among different human and animal strains of virus

hantavirus pulmonary syndrome genome

enveloped with helical nucleocapsid, 3 segment (-)ssRNA L segment: encodes RNA dependent RNA polymerase M segment: encodes the glycoprotein S segment: encodes 2 nonstructural proteins viral replication in cytoplasm

mycoplasma pneumonia tx

erythromycin, doxycycline, or fluoroquinolones

EBV family and genus and describe virion

f: herpesviridae g: lymphocryptovirus large, enveloped, icosadeltahedral capsules, dsDNA, virions encode proteins (early antigen/EA, viral capsid antigen/VCA, glycoproteins of membrane antigen/ MA) that manipulate host cell and immune responses, DNA replication in nucleus

pharyngitis and tonsillitis mumps virus family, genus and virion

f: paramyxoviridae g: rubulavirus virion is large with (-) ssRNA with a helical nucleocapsid, envelope that contains 2 glycoproteins (fusion protein/F and a viral attachment protein that is either hemagglutinin-neurominidase/HN, hemagglutinin/H or glycoprotein/G) virus replicates in cytoplasm and virions penetrate cell by fusion with plasma membrane and exits via budding w/o killing cells, viruses induce cell-to-cell fusion resulting in giant multinucleated cells/ syncytia

coxsackie A virus family and genus

f: picornaviridae g: enterovirus

ssx of secondary TB

fatigue, fever, weight loss, night sweats, chronic cough, hemoptysis

rhinitis/ rhinovirus genus and family and describe

genus: rhinovirus: most important cause of common cold and URTI family: picornaviridae: virions are small naked icosahedral capsids with (+) ssRNA, viral replication occurs in cytoplasm, viral RNA is translated into polyprotein which is cleaved into enzymatic and structural proteins

streptococcus pneumoniae

gram + coccus, encapsulated (mucoid colonies), colonizes nasopharynx and then spreads to distal sites (lungs, ear, blood), especially in pt with underlying disease (antecedent viral resp disease, inadequate immune defenses that result in poor bacterial clearance form resp tract, alpha hemolysis, optochin susceptible, autolytic changes

corynebacterium general characteristics

gram +, non spore forming rods, arranged in palisades (chinese letters), club shaped cells, metachromatic granules of polymerized phosphates

n. gonorrhoeae pharyngitis

gram - cocci that is a maltose nonfermenter, often asymptomatic but does resemble strep throat when there is symptoms

most common cause of LRI in institutionalized adults

gram - rods, s. pneumoniae, s. aureus

**** heterophile antibody positive infectious mononucleosis

heterophile antibodies result form the nonspecific mitogen like activation of B cells by EBV and the production of a wide repertoire of Ab, presence of these Ab are indication of EBV infection ssx triad*** lymphadenopathy, splenomegaly, exudative pharyngitis ssx: fever, fatigue, malaise, hepatosplenomegaly, rash

S. pyogenes characteristics

group A strep, gram + cocci in pairs and long chains, beta hemolytic, encapsulated, **catalase negative, **bacitracin (A disk) susceptible

most common causative agent of LRI in pt with COPD

h. infuenzae, k. pneumoniae

clinical syndromes for sin nombre virus

hantavirus pulmonary syndrome/ HPS and hantavirus cardiopulmonary syndrome - potential risk activities: opening and cleaning unused building, housecleaning, work related exposure, campers and hikers - initial ssx are similar to HFRS: headache, fever, chills, nausea, cough, myalgia, fatigue -late symptoms appear 4-10 days after initial ssx: coughing, SOB, pulmonary edema - ssx results in respiratory failure and death within days if untreated - ***rash, rhinorrhea, pharyngitis, and conjunctivitis are rare in HPS/HCPS - *** a mild nonspecific prodrome with a fulminant course - *** PE findings: tachypnea, tachycardia, hypotension, crackles or rales heard

CMV family, and describe core features

herpesviridae *** CMV is most common viral cause of congenital defects opportunistic pathogen in immunocompromised pt

s. pyogenes epidemiology

humans are natural reservoir, asymptomatic colonization in upper respiratory tract and transient colonization of skin, can survive on dry surfaces for long periods, person to person spread by resp droplets (pharyngitis) or through breaks in skin after direct contact with infected pt, fomite, or arthropod vector

c. diphtheriae epidemiology

humans are only reservoir with carriage in oropharynx or on skin surface, spread person to person by exposure to respiratory droplets or skin contact, disease observed in unvaccinated people living in crowed urban area, uncommon in US

m. tuberculosis disease

humans are very susceptible to infection but resistant to disease, primary infection is pulmonary, dissemination to any body site occurs most commonly in immunocompromised pts and untreated pts (miliary TB)

cell wall structures in strep

hyaluronic acid capsule may be present in some strains but it is not required for virulence but does prevent phagocytosis

tuberculin skin test/ PPD

identifies infection past or present and with or w/o disease, based upon delayed hypersensitivity rxn, purified protein derivatives (PPD) which is injected intradermally, read after 48-72 hrs, if positive then do a CXR

CMV - infection in immunocompromised host:

in lungs: pneumonia and pneumonitis and can be fatal causes retinitis, colitis, esophagitis in pt that are severely immunodeficient ***responsible for failure of many kidney transplants: caused by virus replication in the graft after reactivation in the transplanted kidney or host infection

pharyngitis and tonsillitis EBV epidemiology

incubation can last up to 2 mons -disease/ virulence factors: virus causes lifelong infection, recurrent disease is cause of contagion, virus may cause asymptomatic shedding -transmission: close oral contact/ sharing of saliva via kissing or sharing items like toothbrushes and cups - children experience asymptomatic or mild disease, teenages and adults are at risk for infectious mononucleosis

pharyngitis and tonsillitis coxsackie A virus clinical syndromes

incubation period of 4-14 days most common result of infection is lack of ssx or mild URTI or flulike disease infection results in vesicular ulcerated lesions around the soft palate and uvula called herpangina ssx: fever, sore throat, painful swallowing, anorexia, vomiting

middle east respiratory syndrome/ MERS

infection primarily occurs in the arabian peninsula, is zoonosis, bats and camels are natural reservoir, has a 50% mortality rate

TB infection vs disease

infection: MTB present, TB skin test +, CXR normal, sputum smears and cultures negative, no ssx, not infectious, not defined as case of TB disease: MTB present, TB skin test +, CXR reveals lesion, sputum smears and culture +, ssx such as cough fever weight loss, often infectious before tx, defined as case of TB

pharyngitis and tonsillitis EBV clinical syndromes

infectious mononucleosis, heterophile Ab positive infectious mononucleosis, chronic disease, EBV induced lymphoproliferative disease, african burkett lymphoma, nasopharyngeal carcinoma, hairy oral leukoplakia

epidemic keratoconjunctivitis:

irritation of eye by a foreign body or debris, this irritation is a risk factor for adenovirus infection, typically an occupational hazard for industrial workers

paracoccidioides tx

itraconazole

most common causative agent of LRI in pt with alcohol abuse

klebsiella pneumoniae, oral anaerobic bacteria

legionnaires' disease tx

macrolides and fluoroquinolones

thumb sign on Xray

manifestation of an enlarged epiglottis seen on radiograph of neck, this sign supports the dx of epiglottis caused by h. influenzae type B

c. diphtheriae dx

metachromatic granules can be useful culture: nonselective (blood agar) or selective (cysteine tellurite agar, tinsdale agar) that differentiates b/n c. diphtheriae and other bacteria isolated from pharynx demonstration of exotoxin is performed by PCR or Elek test

EBV african burkett lymphoma/ AfBL

monoclonal B cell lymphoma of jaw and face that is endemic to children in malarial regions of africa and papaua new guinea, malaria is a cofactor is progression of chronic or latent EBV infection in AfBL due to it weakening T cell control of EBV

CMV - infection of children and adults: **

most infections are asymptomatic but pts show a heterophile negative mononucleosis syndrome... ssx are similar to EBV but with less severe pharyngitis and lymphadenopathy, CMV infected cells show T cell outgrowth/ atypical lymphocytes, the virus does not infect B cells so no heterophile Ab

antigenic drift vs antigenic shift

mutation: antigenic drift reassortment: antigenic shift Sudden Shift is more deadly than graDual Drift

most common causative agent of LRI in pt with military recruits and college students

n. meningitidis

CMV -transmission via transfusion and transplant:

often leads to asymptomatic infection, but possible ssx include fever, splenomegaly, atypical lymphocytosis, pneumonia, hepatitis

EBV hairy oral leukoplakia

opportunistic manifestation of EBV in AIDS pt, infection of epithelial cells characterized by lesions on tongue and mouth

rhinitis/ rhinovirus pathogenesis and immunity

over 100 serotypes, most rhinoviruses bind to common receptor= intracellular adhesion molecule 1/ ICAM-1 (surface glycoprotein expressed on endothelial cells and cells of immune system like leukocytes, T and B cells), rhinoviruses are unable to replicate in GI tract due to being labile to acidic pH, growth occurs in nasal mucosa due to optimal growth temp being 33C, virus enters through nose, mouth or eyes and sets up infection in URT, virus replication primarily occurs in nose- bradykinin and histamine released from infected cells cause the runny nose, cytokine release during inflammation contributes to spread of virus by enhancing expression of ICAM-1 viral receptors immunity is transient (~18 mons), reinfection is likely because of number of serotypes and antigenic drift, nasal secretory IgA and serum IgG can be detected within a week of infection

otitis external causes

p. aeruginosa

mumps virus clinical syndromes

parotitis with fever these may occur a few days after onset of infection in absence of parotitis: epididymoorcitis, oophoritis, mastitis, pancreatitis, thyroiditis, meningoencephalitis

GAS pharyngitis tx

penicillin unless allergic abx helps prevent non-suppurative sequelae later such as rheumatic fever

blastomyces dermatitidis cutaneous lesion

person to person spread of blastomycosis can also occur by direct contact with skin lesions, ***can be confused with squamous cell carcinomas, typically painless and in exposed areas

RSV

primarily infects infants and young children, most common cause of fatal acute respiratory tract infection, infects almost everyone by 2 YO, seen among elderly persons, re-infections occur throughout life

b. pertussis tx

primarily supportive macrolides (erythromycin, azithromycin) can be used for tx but they are often of limited use because the disease is generally unrecognizable during most infectious stages (reduces length and severity, complete recovery depends largely on how quickly the ciliated epithelial cells regenerates), Post exposure prophylaxis is important and use azithromycin

complications of influenza virus infection

primary viral pneumonia, secondary bacteria pneumonia (usually involves strep pneumonia, h. influenzae, s. aureus), myositis and cardiac involvement, neurologic syndromes such as guillian barre syndrome, encephalopathy, encephalitis, reye syndrome

most common causative agent of LRI in pt with cystic fibrosis

pseudomonas aeruginosa, s. aureus

EBV induced lymphoproliferative disease

pt lacking T cell immunity are prone to suffer life threatening polyclonal leukemia like B cell proliferative disease and lymphoma with EBV infection male pts with congenital deficiencies of T cell function likely suffer X linked lymphoproliferative disease, post transplant lymphoproliferative disease when recipient undergo immunosuppresive therapy

s. pyogenes scarlet fever clinical presentation

rash appears on chest and spreads to the trunk and limbs lasting 5-7 days, after rash the skin desquamates, pastia's line

mumps virus dx

recover virus from saliva, urine, pharynx, secretions from the parotid (Stensen) duct, and cerebrospinal fluid RT-PCR ELISA, immunofluorescence, hemagglutination inhibition test

EBV chronic disease

recurrent disease: chronic tiredness, low grade fever, headache, sore throat

rhinitis/ common cold causes

rhinovirus, coronavirus, influenza C virus, coxsackie virus type A and B, parainfluenza virus

most common causative agent of LRI in pt with IV drug abuse

s. aureus

most common causative agent of LRI in pt with elderly with recent influenza infection

s. aureus

otitis media causes

s. pneumoniae, h influenzae type B, m. catarrhalis, s. agalactiae

sinusitis causes

s. pneumoniae, h. influenza B, m. catarrhalis, s. aureus

most common cause of LRI in 5-18 mon olds

s. pneumoniae, h. influenzae

most common cause of LRI in older adults (~50 and over)

s. pneumoniae, legionella spp

rhinitis/ coronavirus clinical syndromes

similar to rhinovirus but with longer incubation period of about 3 days ssx: sneezing, rhinorrhea, nasal obstruction, headache, malaise, low grade fever

pseudomonas aeruginosa

small gram - rods typically in pairs, motile, obligate aerobe, ** oxidase and catalase positive, ** mucoid slime layer form glycocalyx, ** grape like odor, **blue green pigment, colonies spreading and flat with a pearl like sheen

haemophilus spp characteristics

small gram - rods, sometimes pleomorphic ***blood loving so culture on chocolate agar: fastidious organism, require X (hemin) and V factors (NAD... V for vitamin) requires both X and V factors - SBA only has x factor directly available, NADase destroys V factor - chocolate agar: both X and v factor -satellitism: growth of fastidious organisms around other bacteria that release necessary growth factors, bacteria that cause hemolysis of RBCs release the factors or naturally produce V factor, H. influenzae satellite obtains X factor from SBA and V factor from the other bacteria

A 46-year-old male with a history of alcohol abuse is brought to the emergency department with a temperature of 104.3 degrees F. He coughs up thick, red-black sputum while being evaluated. Chest x-ray shows an abscess in the left upper lobe. The most likely diagnosis is: Streptococcus pneumoniae Haemophilus influenzae Blastomycosis Klebsiella pneumoniae Mycoplasma pneumoniae

strep pneumoniae

s. pyogenes pharyngitis clinical features

strep throat reddened pharynx with exudates generally present cervical lymphadenopathy can be prominent **difficult to distinguish from pharyngitis caused by other pathogens; most common cause of bacterial pharyngitis in children findings suggestive of GAS: sore throat, sudden onset, fever, pain swallowing, headache, lymphadenitis, tonsillar exudates, soft palate petechiae suppurative complications: abscess, sepsis, dissemination

most common bacterial causes of pneumonia

strep. pneumoniae s. aureus klebsiella pneumoniae other enterobacteriaceae

m. tuberculosis dx

tuberculin skin test and quantiferon test sensitive marker for exposure to organism, microscopy and culture are sensitive and specific, ID most commonly made using species specific molecular probes

diseases caused by group A strep

suppurative: pharyngitis, tonsillitis, adenitis, meningitis, sinusitis, otitis, scarlet fever, toxic shock syndrome, puerperal fever, pneumonia, impetigo, cellulitis, necrotizing fascitis, myositis, osteomyelitis non-suppurative sequelae: acute rheumatic fever, carditis, chorea, polyarthritis, subcutaneous nodules, erythema marginatum

s. pyogenes scarlet fever

toxigenic disease that is mediated by streptococcal pyrogenic exotoxin, multi system involvement, complication of strep pharyngitis

pharyngitis and tonsillitis coxsackie A virus epidemiology

transmission via fecal oral route due to poor hygiene, poor sanitation, crowded living conditions, and dirty diapers, ingested of contaminated food and water, contact with infected hands and formites, inhalation of infectious aerosols asymptomatic shedding of virus occurs for up to a month viral disease is more severe in adults than in children

rhinitis/ rhinovirus epidemiology

transmission via inhalation of aerosols and direct contact with infected hands and formites, virus is stable and survives on objects for hours, increase incidences occur in winter due to closer and more prolonged contact with individuals

c. diphtheriae tx, prevention

tx: infections tx with diphtheria antitoxin to neutralize exotoxin is only effective before toxin attaches to cells****; penicillin or erythromycin p: immunization of convalescent pt with diphtheria toxoid to stimulate production of protective Ab

hantavirus pulmonary syndrome tx and prevention/ control

tx: no approved antiviral, supportive tx, if pt survives the recovery is relatively rapid but can be long lasting airway damage p/c: no vaccine, rodent control

adenovirus tx and prevention/ control

tx: no approved tx, cidofovir and ribavirin are use to tx immunocompromised pt p/c: careful handwashing and chlorination of swimming pools reduces transmission, live oral vaccines prevent infection from adenovirus types 4 and 7, but only used in military

s. pneumoniae tx and prevention

tx: penicillin is drug of choice, resistance to beta lactams, macrolides, folate inhibitors, and tetracycline is beginning to be a problem; empiric tx until abx susceptibility data is available p: pneumococcal vaccines, PCV ( pneumococcal conjugate vaccine), PPSV (pneumococcal polysaccharide vaccine)

parainfluenza virus

viral croup - usually cause mild cold like ssx but may also cause serious respiratory tract disease - there are 4 serologic types of human parainfluenza viruses: --types 1, 2, 3, are the 2nd most important causes of severe LRI in infants and young children: associated with laryngotracheobronchitis/ croup --type 4 causes mild URI in children and adults

rhinitis/ coronavirus pathogenesis

virus infects epithelial cells of URT, optimal temp of growth is 33-35C so virus infection remains localized in URT, transmission by aerosols, reinfection occurs in presence of serum Ab

*** infectious mononucleosis:

war b/n EBV infected B cells and protective T cells, T cell activation and proliferation causes lymphocytosis, swelling of lymphoid tissues, malaise, fatigue due to energy it takes the body to build up T cell response

severe acute respiratory syndrome/ SARS

zoonosis, 1st outbreak in guangdong providence in china occurred when animal reservoirs (commonly raised by food, ex: civets, raccoon dogs, chinese ferret badgers) came in contact with humans; most likely transmitted in respiratory droplets v]but the virus may also be present in sweat, urine, feces

describe acute pharyngitis pathogenesis

~70% of acute sore throats are caused by viruses, viruses infect URT and encounter the submucosal lymphoid tissues around oropharynx, sore throats are the result of the virus infected mucosa or the inflammatory and immune responses in lymphoid tissues