MICRO EXAM #4

Pathogenesis of a Boil

(Furuncle) Staphylococcus aureus infects a hair follicle through its opening on the skin surface. The infection produces a plug of necrotic material, a small abscess in the dermis, and finally, a larger abscess in the subcutaneous tissue

Escherichia coli Gastroenteritis

1.Pathogenic strain of E. coli enters by the fecal-oral route, either directly from an infected person or with contaminated food or drink. 2.Most strains colonize the small intestine and produce watery diarrhea. 3.Others invade the large intestine and cause dysentery. 4.Some strains produce Shiga toxin, which is absorbed by the bloodstream and causes hemolytic-uremic syndrome. 5.The bacteria exit the body with feces

Which of the following may be added to normal media to make it more selective for staphylococci?

7.5% salt

Blood and lymph may carry

A) antibodies. B) lysozyme. C) interferon. D) complement. E) All of the choices are correct

Which of the following is NOT a virulence factor of Streptococcus pyogenes?

A-B exotoxin

Salmonella gastroenteritis

About 1.2 million cases in U.S. each year Outbreaks due to foods contaminated by animal fecesSigns and symptoms Diarrhea, vomiting, headache, abdominal pain, and fever Incubation period Usually 6 to 72 hours Causative agent Salmonella enterica, Gram-negative, member of the Enterobacteriaceae Pathogenesis Induce uptake by epithelial cells in the distal small intestine; bacteria multiply in the phagosome and then are discharged at the base of the cell; inflammatory response increases fluid secretion Epidemiology Ingestion of food contaminated by animal feces, especially poultry Treatment and prevention Treatment: antimicrobial medication is generally not advised. Prevention: relies on adequate cooking and proper handling of food.

Enlargement of which of the following structures may contribute to ear infections by interfering with normal drainage from Eustachian tubes?

Adenoids

Yellow fever is transmitted by

Aedes mosquitoes

Corynebacterium

Aerobic or facultatively anaerobic. Those that look similar to C. diphtheriae, the cause of diphtheria, are included in a group calle d diphtheroids

Moraxella

Aerobic. Some microscopically resemble pathogenic Neisseria species such as N. meningitidis

Streptococcus

Aerotolerant (obligate fermenters). Viridans streptococci, which are α-hemolytic (greenish partial hemolysis), and non-hemolytic streptococci are common. β-hemolytic (clear hemolysis) streptococci and the potential pathogen S. pneumoniae may also be present

The scientist responsible for the development of the first anti-plague vaccine in 1866 was

Alexandre Yersin

Which of the following conditions is important in the ecology of the skin? Temperature Salt concentration Lipids pH

All of the above

Which of the following contributes to the virulence of Streptococcus pyogenes? Protease Hyaluronidase DNase

All of the above

Which of the following virulence factors used by Staphylococcus puts holes in host cells?

Alpha toxin

The causative agent of whooping cough is

B. pertussis

The causative agents of pertussis and tuberculosis differ in that

B. pertussis produces exotoxins that damage the host, while M. tubercuosis does not

Brucellosis may also be known as

Bang's disease OR undulant fever

Pathogenesis of Streptococcus pyogenes

C5a peptidase Inhibits recruitment of phagocytes by destroying complement component C5a Hyaluronic acid capsule Interferes with phagocytosis by causing inactivation of complement component C3b, an opsonin; involved in attachment to host cells M protein causing inactivation of complement component C3b, an opsonin Protein F Responsible for attachment to host cells Protein G Binds to Fc portion of antibodies, thereby interfering with opsonization Streptococcal pyrogenic exotoxins (SPEs) Superantigens responsible for scarlet fever, toxic shock, "flesh-eating" fasciitis Streptolysins O and S Lyse leukocytes and erythrocytes Tissue-degrading enzymes Enhance spread of bacteria by breaking down DNA, proteins, blood clots, tissue, hyaluronic acid

All of the following must be cultivated in cell cultures instead of cell-free media except

Candida albicans

Both S. pneumoniae and K. pneumoniae use this as a virulence factor

Capsules

What is eschar (a sign of cutaneous anthrax)?

Dead tissue resembling a flat scab

Superficial Cutaneous Mycoses

Dermatophytes cause athlete's foot, ringworm, and invasions of the hair and nails

Which is used in the vaccination for C. diphtheriae?

Exotoxin

The stomach

Expandable, sac-like structure with muscular wall. Breaks down and stores food ▪ Highly acidic gastric juices denature proteins, activate pepsinogen to form proteindigesting enzyme pepsin ▪ Cells lining stomach protected by alkaline mucus ▪ Most bacterial cells cannot survive, so normal empty stomach has few

This chemical compound, typically added to drinking water, makes enamel more resistant to dissolving in acid.

Fluoride

The varicella-zoster virus is a member of which virus family?

Herpesviridae

Which of the following is associated with the upper respiratory system?

Humidifying inhaled air AND warming inhaled air

The upper digestive system

Includes mouth, salivary glands, esophagus, stomach

The Lower Respiratory Tract

Includes the larynx (voice box), trachea (windpipe), bronchi, and lungs ▪ The trachea is a continuation of the larynx and branches into two bronchi. ▪ The smallest bronchioles end in the alveoli, which are tiny, thinwalled air sacs where gas exchange occurs. ▪ The lungs are surrounded by two membranes called pleura; one adheres to the lung and the other to the chest wall and diaphragm

Which of the following infectious agents is most likely to cause a pandemic?

Influenza A virus

Which of the following statements about the spleen is false?

It routinely produces new blood cells

The process used for identifying the different carbohydrates of streptococci is called

Lancefield grouping

Which of the following is caused by a protozoan?

Malaria

Which of the following normal skin microbiota is a small yeast?

Malassezia species

Bacterial Infections of the Upper Respiratory System

Pink Eye, Earache, and Sinus Infections Common, often occur together, often from same agent • Signs and symptoms • Conjunctivitis ("pink eye"; inflammation of the eye surface): tears, redness, swollen eyelids, sensitivity to bright light, pus • Otitis media [inflammation of the middle ear]: severe earache; pain often causes vomiting • Sinusitis [inflammation of the sinuses]: facial pain, pressure; headache, malaise, thick green nasal discharge may develop • Causative agents ▪ Haemophilus influenzae (Gramnegative rod) and Streptococcus pneumoniae (Gram-positive encapsulated diplococcus) ▪ Strains that infect conjunctiva have adhesins ▪ Approximately one third of otitis media, sinusitis caused by respiratory viruses

The following are all complications of streptococcal pharyngitis except

Reye's syndrome

If a woman begins to develop shingles, which of the following can you conclude?

She had chickenpox in the past

Campylobacteriosis

Signs and symptoms ▪ Incubation period 1 to 11 days; usually 2 to 5 days ▪ Fever, vomiting, diarrhea, abdominal cramps ▪ Dysentery occurs in about half the cases Causative agent: Campylobacter jejuni ▪ Curved, Gram-negative rod first isolated in 1972 ▪ Can be cultivated under microaerophilic conditions with a selective medium Pathogenesis Penetrate epithelial cells of small and large intestines, cause localized inflammatory reaction Up to 40% of Guillain-Barré syndrome cases preceded by campylobacteriosis; autoimmunity likely involved

Escherichia coli gastroenteritis

Signs and symptoms ▪ Some cause watery diarrhea, others dysentery ▪ One group causes hemolytic uremic syndrome (HUS) Causative agent: Escherichia coli ▪ Gram-negative rod closely related to Shigella ▪ Unlike Shigella, most strains ferment lactose

The lower digestive system

Small and large intestines, pancreas, liver

is a common resident on the skin surface but is relatively harmless. ______ is found mostly in the nostrils and may lead to serious hair follicle infections.

Staphylococcus epidermidis; Staphylococcus aureus

Complications of measles may include pneumonia and encephalitis

T

Which statement about rotavirus gastroenteritis is false?

The causative agent infects mainly the stomach

Choose the most accurate statement about cryptosporidiosis

The life cycle of the causative agent occurs within small intestinal epithelial cells

Pathogenesis of otitis media, sinusitis

Usually preceded by infection of nasal cavity and pharynx that spreads through Eustachian tube • Infection damages ciliated cells, results in inflammation and swelling, prevents movement of secretions. Fluid, pus collect behind eardrum, cause pressure, Eardrum may burst • Biofilm may lead to chronic infections

Pertussis ("whooping cough")

Vaccination-preventable disease, but still endemic in many countries including U.S. ▪ Causes up to half a million deaths annually globally Signs and symptoms: three stages 1. Catarrhal stage (inflammation of mucous membranes) ▪ 1 to 2 weeks of signs resembling upper respiratory infection (runny nose, sneezing, low fever, mild cough) 2. Paroxysmal stage (repeated sudden attacks) ▪ Frequent bursts of violent uncontrollable coughing lasting 2 to 4 weeks or longer ▪ Dry but severe; small blood vessels in eyes rupture, tongue protrudes, neck veins stand out ▪ Forceful inhalation of air: "whoop" sound. Vomiting, seizures, cyanosis may occur 3. Convalescent stage (recovery) ▪ Not contagious; coughing decreases over several weeks Causative agent: ▪ Bordetella pertussis, Tiny encapsulated aerobic Gram-negative rod ▪ Sensitive to sunlight, drying: quickly die outside of host Pathogenesis: ▪ cells are inhaled, attach to ciliated cells of epithelium ▪ Increased mucus production, decreased ciliary action results in severe cough ▪ Some bronchioles completely obstructed, lead to small areas of collapsed lung. Spasms, partial mucus plugging let air enter but not escape ▪ Three toxins released: Pertussis toxin (PT) is A-B exotoxin: B attaches to receptors, A moves through cytoplasmic membrane ▪ Increases cAMP: yields increased mucus, decreased killing ability of phagocytes, release of lymphocytes into bloodstream, ineffectiveness of natural killer cells, low blood sugar ▪ Adenylate cyclase (ACT) lyses leukocytes; catalyzes ATP to cAMP ▪ Tracheal cytotoxin (TCT) causes release of fever-inducing interleukin-1; toxic to ciliated epithelial cells Epidemiology: highly contagious ▪ Spread via respiratory secretions suspended in air ▪ Patients most infectious during catarrhal stage ▪ Classically disease of infants; most fatalities in those under 1 year of age Treatment and prevention ▪ Macrolides during catarrhal stage; ineffective in paroxysmal stage ▪ Intensive supportive therapy sometimes needed in infants ▪ Prevented with acellular pertussis vaccine (aP) given in combination with diphtheria and tetanus toxoids (DTaP) ▪ Additional booster for adolescents (Tdap) ▪ Also given to pregnant women to provide passive immunity to newborn

The plague bacillus is known as

Yersinia pestis

Which statement about Yersinia pestis is false?

Yops (proteins) increase phagocytosis

The diarrhea of cholera has been described as

a rice water stool

Vibrio cholerae pathogenesis involves all of the following except

acid resistance

Shigella moves from cell to cell using

actin tails

The disease that closely resembles "strep throat" but is of viral origin is

adenoviral pharyngitis

Staphylococcus aureus can be responsible for all of the following conditions except

athlete's foot

Adenoviral infections and the common cold are both

avoided by handwashing

The spleen, in part, functions to cleanse the

blood

S. aureus clumping factor

causes bacteria to clump together in plasma

Collections of bacteria that adhere to the surfaces of the teeth are called

dental plaque

The passage from the mouth to the anus is termed the

gastrointestinal tract

The inflammatory effect of immune complexes lodged in the kidney is called

glomerulonephritis

The condition that develops on a previously damaged heart valve is called

infective endocarditis

The pancreas:

located behind stomach. Produces hormones, alkaline digestive enzymes

Although sepsis affects many organs, the organ(s) most seriously and irreversibly affected is/are the

lungs

Warts are caused by

papillomaviruses

The sudden, violent, uncontrollable cough of pertussis is described as

paroxysmal

The "Black Death" may also be known as

plague

The common name for tularemia is

rabbit fever

Viral gastroenteritis in infants and children is most commonly caused by

rotavirus

The virulence of the tubercle bacillus is due to its

survival within macrophages

All of the following are true of diphtheria except

the causative organism typically invades the bloodstream.

Helicobacter pylori appears to have some connection with

ulcers AND stomach cancer

The secretions of the sweat and sebaceous glands provide ________ to the microbiota

water, amino acids, AND lipids

Rubella (German Measles)

1.Airborne rubella virus infects nose and throat. 2.Virus enters lymph nodes in the region. 3.Rubella virus multiples and enters the bloodstream. 4.Circulating virus reacts with antibodies, resulting in immune complexes. 5.Immune complexes lodge in the skin, causing a mild rash, and in the joints, causing pain. 6.In pregnant women, rubella virus crosses the placenta, infecting the fetus, resulting in congenital rubella syndrome. 7.Transmission to others is by respiratory secretions Signs and symptoms Mild fever and cold symptoms, rash beginning on forehead and face, enlarged lymph nodes behind the ears; joint pain in adults Incubation period 14 to 21 days Causative organism Rubella virus, an enveloped RNA virus Pathogenesis Following replication in the upper respiratory tract, virus spreads to all parts of the body and crosses the placenta; surviving fetuses often develop abnormally and excrete the virus for months after birth. Epidemiology Virus typically present in nose and throat from 1 week before rash to 1 week after; infection occurs via the respiratory route; humans are the only source. Treatment and prevention Treatment: no specific antiviral treatment. Prevention: attenuated vaccine (MMR or MMRV).

Rubeola (Measles)

1.Rubeola virus spread by air or direct contact infects the upper respiratory tract, then the lymph nodes in the region. 2. Virus enters the bloodstream and is carried to all parts of the body, including the brain, lungs, and skin. 3. Skin cells infected with the rubeola virus are attacked by cytotoxic T cells, causing a generalized rash. 4. Virus replicating in the lungs can cause pneumonia; the brain can also be infected. 5.In rare cases, virus persisting in the brain causes subacute sclerosing panencephalitis, months or years after the acute infection. 6. Secondary infection of the ears and lungs is common. 7.Transmission is by respiratory secretions Signs and symptoms Rash, fever, weepy eyes, cough, nasal discharge, and sometimes diarrhea. Incubation period 10 to 12 days Causative organism Rubeola virus, an enveloped single-stranded RNA paramyxovirus Pathogenesis Virus multiplies in respiratory tract; spreads to lymphatic tissues, then to all parts of body, notably skin, lungs, and brain; damage to respiratory tract epithelium leads to secondary infection of lungs (pneumonia) and ears. Epidemiology Acquired by respiratory route; highly contagious; humans only source. Treatment and prevention Treatment: no antiviral treatment. Prevention: attenuated vaccine (MMR or MMRV).

Strep Throat (Streptococcal Pharyngitis) and Post-Streptococcal Sequelae

1.Streptococcus pyogenes enters by inhalation (nose), or by ingestion (mouth). 2.Pharyngitis, fever, enlarged lymph nodes; scarlet fever with strains that produce erythrogenic toxin. Symptoms go away. 3.S. pyogenes exits by nose and mouth. Late complications appear: 4.Glomerulonephritis 5.Rheumatic fever affects heart and joints. 6.Rheumatic fever may cause neurological abnormalities resulting in chorea. Complications subside. 7.Heart valves damaged by rheumatic fever leak; heart failure develops. Signs and symptoms Sore, red throat, with pus and tiny hemorrhages, enlargement and tenderness of lymph nodes in the neck; occasionally, rheumatic fever and glomerulonephritis as sequelae Incubation period 2 to 5 days Causative agent Streptococcus pyogenes, Lancefield group A β-hemolytic streptococci Pathogenesis Virulence associated with hyaluronic acid capsule and M protein, both of which inhibit phagocytosis; protein G binds Fc segment of IgG; protein F allows bacteria to attach to mucous membranes; multiple enzymes damage tissues Epidemiology Direct contact and droplet infection; ingestion of contaminated food. Treatment and prevention Treatment: appropriate antibiotic. Prevention: avoiding crowds; adequate ventilation; daily penicillin to prevent recurrent infection in those with a history of rheumatic heart disease.

Cholera

1.Vibrio cholerae enters the mouth with fecally contaminated food or drink. 2.The bacteria attach to epithelial cells of the small intestine. 3.Cholera toxin enters the cells and causes them to continuously secrete chloride ions. Other electrolytes and water follow. 4.The outpouring of water and electrolytes into the intestinal lumen causes watery diarrhea. 5.Fluid loss causes severe dehydration, resulting in shock and death unless the fluid can be replaced. 6.The bacteria exit the body with feces

The lower digestive system The large intestine

Absorbs water; vitamins produced by resident microbiota ▪ Degrade wide variety of foods including substances (for example, fibers) indigestible by stomach, small intestines ▪ Important to human health: synthesize vitamins (like niacin, thiamine, riboflavin,, vitamin B_12, folic acid, vitamin K) ▪ Prevent pathogens from colonizing; stimulate mucosal immunity; opportunistic pathogens ▪ Antibiotic treatment causes dysbiosis (imbalance in normal microbiota), that may lead to antibiotic-associated diarrhea

Bacterial Infections of Lower Respiratory System-Pneumococcal pneumonia

Account for approximately 60% of adult community-acquired pneumonia patients requiring hospitalization Signs and symptoms: cough, fever, chest pain, sputum production (incubation period 1 to 3 days) • Usually preceded by 1 to 2 days of runny nose, congestion that ends with sudden fever and shaking chills • Sputum becomes pinkish or rust-colored from blood • Severe chest pain aggravated by each breath or cough • Causes shallow rapid breathing • Patient develops cyanosis from poor oxygenation • Without treatment, survivors sweat heavily and return to normal temperature after 7 to 10 days Causative agent: Streptococcus pneumoniae ▪ Gram-positive diplococcus known as pneumococcus; lancet-shaped ▪ Thick polysaccharide capsule responsible for virulence ▪ 90 different serotypes each with different capsular antigens ▪ Certain serotypes more commonly invasive ▪ Strains lacking capsule do not cause invasive disease Pathogenesis: ▪ Capsule, pneumococcal surface protein (PspA) interfere with C3b of complement system, block phagocytosis ▪ Pneumolysin damages ciliated epithelium ▪ Accumulations in alveoli cause difficulty breathing; sputum coughed from lungs ▪ Pneumococci may enter blood-stream, lead to sepsis of blood, endocarditis (heart valve infection), meningitis (infection of brain, spinal cord membranes) ▪ In several days, antibodies allow phagocytosis and destruction of pneumococci, recovery Epidemiology: ▪ up to 30% of healthy people carry encapsulated pneumococci in throat; mucociliary escalator effectively keeps from reaching lungs ▪ Risk of infection increases when this defense is impaired ▪ Increased risk in those over 50, or with heart or lung disease, diabetes or cancer Treatment and prevention: ▪ penicillin cures if given early; resistant strains increasingly common ▪ Conjugate vaccine (PCV13) against 13 strains available for children under 2, adults over 65 and those with certain health conditions ▪ Vaccine (PPSV23) available for 23 most common pneumococcal strains

Acne Vulgaris

Acne in its most common form begins at puberty in association with a rise in sex hormones. Sign and symptoms: Acne is characterized by enlarged sebaceous glands and increased secretion of sebum. Causative Agent: Cutibacterium (Propionibacterium) acnes Pathogenesis: The metabolic products of the dividing bacteria cause an inflammatory response Treatment and Prevention: The length of infection can be limited by medications such as antibiotics and benzoyl peroxide

Which of the following infection fighters are found in lymph? Leukocytes Antibodies Complement Interferon

All of the above

Which of the following is considered a function of the skin? Production of cytokines Synthesis of vitamin D Regulation of body temperature Prevention of fluid loss All of the choices are correct.

All of the choices are correct

Cutaneous Anthrax

Anthrax is rare in humans. It may, however, occur when endospores Bacillus anthracis enter the body by inhalation, ingestion, or contact with the skin Signs and Symptoms ▪ small red bump within a few days ▪ Bump develops blisters, eventually forms ulcer surrounded by swelling ▪ Black eschar covers center of area and persists for several weeks ▪ Seldom results in scarring Causative agent: Bacillus anthracis Endospore-forming, Gram-positive, non-motile rod Named for black "coal-like" scabs Endospore is infectious form; germinate to form toxin-producing vegetative cells in host Pathogenesis Virulence due to capsule and exotoxins Cutaneous anthrax not likely to become systemic Epidemiology Seen in people who work with animals or animal products (farmers, leather tanners, etc.) No person-to-person transmission Treatment and prevention Antimicrobial medication for 7 to 14 days Vaccine available for those at greatest risk

Treatment and prevention

Antibiotics generally effective when properly used ▪ Proper use decreases risk of complications (for example, meningitis) ▪ Decongestants, antihistamines generally ineffective; can actually reduce immune response ▪ Preventive measures include handwashing, avoiding touching eyes ▪ Preventive measures for otitis media include plastic tubes through eardrums if chronic, influenza vaccine, or removal of adenoids to improve drainage

Viral Infections of the Lower Respiratory System Influenza ("Flu")

Antigenic changes responsible for serious annual epidemics; infects approximately 20% of humans annually ▪ Three major virus types based on protein coat; type A causes most serious disease Signs and symptoms: ▪ Headache, muscle aches, fever, sore throat, fatigue; peaks in 6 to 12 hours; dry cough develops and worsens over a few days (incubation period approximately 2 days) ▪ Acute symptoms last approximately 1 week; lingering cough, fatigue, weakness last additional days or weeks Causative agent: Influenza A in Orthomyxoviridae ▪ Enveloped virus with 8 segments of single-stranded RNA ▪ Glycoprotein spikes embedded in envelope: hemagglutinin antigen (HA) and neuraminidase antigen (NA) ▪ HA attaches to receptors on host epithelial cells ▪ NA critical in release: destroys surface receptors that bind budding virions ▪ Subtypes based on HA and NA ▪ 1997 "avian flu" was H5N1; 2009 "swine flu" was H1N1 ▪ 18 HA, 11 NA subtypes; only H1, H2, H3 and N1, N2 infect humans Pathogenesis: ▪ inhalation of aerosolized secretions or from contaminated fomites ▪ Virions attach by HA spikes to respiratory epithelial cells; enter by endocytosis. Rapid synthesis of viral RNA and proteins ▪ Host membrane embedded with HA and NA; mature virions acquire these as they bud from host cell ▪ Infected cells die, slough off, destroy mucociliary escalator Epidemiology ▪ Epidemics occur annually; pandemics periodically ▪ Antigenic drift: minor mutations in HA and NA genes; responsible for seasonal influenza ▪ Antigenic shift: uncommon; concurrent infection allows mixture of 8 RNA segments; causes pandemic influenza ▪ Human strain can gain novel HA and/or NA antigens to which humans have no immunity Treatment and prevention: ▪ Antiviral medications such as neuraminidase inhibitors ▪ Variety of trivalent or quadrivalent vaccines Influenza Virus: Antigenic Drift and Antigenic Shift With drift, repeated mutations cause a gradual change in the HA and/or NA spikes, so that antibodies against the original virus become progressively less effective. With shift, there is a sudden major change in the spikes because the virus acquires a new genome segment.

The small intestine

As stomach contents enter, pancreas and liver add alkaline digestive fluids that neutralize acid ▪ Emulsifying agent bile, helps break down fat globules; help absorb oils, fats, fatsoluble vitamins ▪ Villi, microvilli increase surface area to about 250 meters squared ▪ Major role in nutrient and fluid absorption. Fatty acids, vitamins, minerals absorbed ▪ Dendritic cells, M cells, and Peyer's patches monitor bacterial population

Periodontal disease

Bacterial products in plaque near gum margin trigger inflammation ▪ Gingivitis: swelling and redness of the gums ▪ Chronic periodontitis: destructive response that damages structures that support teeth Signs and symptoms ▪ Gingivitis: gums are tender, bleed easily ▪ Occurs within days of plaque formation; goes away when plaque is removed ▪ Chronic periodontitis: bad breath, red shiny gums that bleed easily, loosening of teeth ▪ Base of teeth becomes discolored, gums recede Causative agent ▪ This infection is polymicrobial, Mostly Gram-negative anaerobes: Porphyromonas, Treponema, Tannerella, Prevotella, and others ▪ Polymicrobial infections; hundreds of species in plaque Pathogenesis ▪ Plaque, tartar accumulate, extend into gingival crevice ▪ Bacterial products incite inflammatory response ▪ Microbes release tissue-degrading enzymes that widen and deepen gingival crevice; allow plaque to spread ▪ Tissues detect LPS endotoxin, release pro-inflammatory cytokines that damage nearby tissues. Membrane attaching root to bone weakens, bone softens, Tooth becomes loose, may fall out Treatment and prevention Cleaning, minor surgery; antibiotics, flossing and brushing

Helicobacter pylori gastritis

Barry Marshall drank culture of Helicobacter pylori in 1980s, demonstrated association with stomach ulcers Signs and symptoms ▪ Most infections asymptomatic ▪ Gastritis with belching, vomiting may occur ▪ Chronic gastritis can lead to stomach cancer ▪ Peptic ulcers produce localized abdominal pain, tenderness, bleeding Causative agent: Helicobacter pylori, Short, curved, Gram-negative microaerophile with multiple sheathed polar flagella Treatment and prevention Antibiotics plus medication to inhibit acid production Pathogenesis ▪ H. pylori survives acidic environment of stomach, Produces urease, which converts urea to ammonia, creating alkaline microenvironment ▪ Burrows within mucus layer that coats stomach lining ▪ Avoids recognition by immune system receptors • VacA (vacuolating cytotoxin) promotes flow of urea, induces apoptosis in epithelial cells, interferes with T cells • CagA (cytotoxin-associated gene) in strains with higher risk of cancer; alters host cytoskeleton, cell signaling • Damage to epithelial cells and inflammatory response results in decreased mucus production, cell damage • Infections persist for years, often for life; 90% of those with stomach cancer are infected Epidemiology Likely transmitted via fecal-oral route Bacteria found in well water

Which of the following organisms is not normally found on the skin?

Candida species

Properties of Staphylococcus aureus Implicated in Its Virulence

Capsule Inhibits phagocytosis Clumping factor Attaches the bacterium to fibrin, fibrinogen, and plastic devices Coagulase May slow progress of leukocytes into infected area by producing clots in the surrounding capillaries Enterotoxins Superantigens cause food poisoning if ingested Exfoliatin Destroys material that binds outer layers of the epidermis together, causing scalded skin syndrome Fibronectin-binding protein Attaches bacterium to acellular tissue substances, endothelium, epithelium, clots, indwelling plastic devices Hyaluronidase Breaks down hyaluronic acid component of tissue, thereby allowing infection to spread Leukocidin Kills neutrophils or causes them to release their enzymes Lipase Breaks down fats to glycerol and fatty acids Proteaes Degrade collagen and other tissue proteins Protein A Binds to Fc portion of antibody, thereby interfering with opsonization that otherwise facilitates phagocytosis Toxic shock syndrome toxin Causes rash, diarrhea, and shock a Toxin Makes holes in host cell membranes

Which is considered the most serious staphylococcal skin infection? Acne Folliculitis Furuncles Tinea versicolor Carbuncles

Carbuncles

Fifth disease

Caused by parvovirus B-19: non-enveloped, single-stranded DNA virus ▪ Preferentially infects bone marrow cells Up to 5% of pregnant women suffer spontaneous abortion

The mouth and salivary glands

Chewing grinds food into smaller pieces; saliva moistens the food, while amylase begins breakdown of starches • Teeth protected by enamel • Proteinaceous material from saliva adheres, creates thin film (pellicle) • Bacteria attach, create biofilm called dental plaque • Mineral salts deposit over time, create dental calculus or tartar • Damage to enamel allows microorganisms to enter tooth, cause decay or dental caries • Gums become inflamed in response: gingivitis • Largest glands are the parotid glands , Rich in protective secretory IgA, antibacterial lysozyme, lactoferrin • Over 600 types of bacteria found in mouth; members of Streptococcus most common

Which of the following may aid Staphylococcus in resisting phagocytosis?

Coagulase

Roseola

Common but mild in children 6 months to 3 years old ▪ Begins abruptly with fever nearing 105 degrees Fahrenheit, ▪ After several days, fever subsides, short-lived red rash appears, disappears in a few hours to 2 days ▪ Caused by herpesvirus type 6 ▪ No vaccine or treatment except to reduce fever

Post-streptococcal sequelae

Complications that develop after streptococcal infections • Thought to result from immune response • Acute rheumatic fever can begin approximately 3 weeks after recovery • Fever, joint pains, chest pains, rash, nodules under skin • Uncontrollable body movements (chorea) can occur • Carditis develops in 30 to 50% of patients, can lead to chronic rheumatic heart disease • Heart valve damage; infective endocarditis • Some MHC class II alleles involved in susceptibility • Thought to involve autoimmune response • Acute post-streptococcal glomerulonephritis • Fever, fluid retention, high blood pressure; blood and protein in urine • Damage to kidneys from inflammatory reaction to streptococcal antigens in kidney glomeruli

Which of the following is an important function of the skin?

Control body temperature

Diptheria

Corynebacterium diphtheriae enters by inhalation. 2. Infection established in throat. 3. Toxin released locally, pseudomembrane forms. 4. Circulating toxin may cause paralysis, or damage heart muscle, kidneys, nerves. 5. Membrane may come loose and obstruct breathing. 6. Exit from body by respiratory secretions

Which of these infections is not transmitted by mosquitoes?

Ebola virus disease

Klebsiella pneumonia

Enterobacteria such as Klebsiella species and other Gram-negative rods can cause pneumonia ▪ Especially if host defenses are impaired ▪ Cause most of the deaths from healthcare-associated infections Signs and symptoms: ▪ cough, chills, shortness of breath, fever, chest pain, cyanosis (incubation period 1 to 3 days) ▪ Most symptoms similar to pneumococcal pneumonia ▪ Distinguished by repeated chills, production of bloody jelly-like sputum Causative agent: ▪ Klebsiella pneumoniae ▪ Gram-negative rod with large capsule; produces big mucoid colonies when cultured on agar Pathogenesis ▪ Contracted through secretions that are transmitted by contact, or from medical equipment (for example, ventilators) ▪ Klebsiella colonize throat; reach lung via inhaled air, mucus ▪ Adhesins aid colonization ▪ Capsule is virulence factor: likely interferes with C3b ▪ Siderophore "steals" iron, causing cellular stress that induces inflammation and spread of bacteria ▪ Tissue death, lung abscesses may cause permanent damage to lung, perhaps leading to death ▪ Often enters blood, causes abscesses, septic shock Treatment and prevention: ▪ Treated with antibiotics, but more strains are developing increasing antibiotic resistance ▪ Commonly produces plasmid-encoded β-lactamase; often produces extended-spectrum β-lactamase (ESBL) as well ▪ Surgery may be required to drain abscesses ▪ No vaccine; follow infection control measures

Typhoid and paratyphoid fevers

Examples of enteric fevers: systemic diseases that originate in the intestine Signs and symptoms ▪ Incubation period of 1 to 4 weeks ▪ Progressively increasing fever over a number of days, severe headache, constipation, abdominal pain ▪ In severe cases, intestinal rupture, bleeding, shock, death Causative agents Salmonella serotypes Typhi and Paratyphi, Cases confirmed by blood culture Pathogenesis ▪ Enteric fevers caused by bacteria that colonize intestines, cross mucous membrane via M cells, multiply within macrophages, and are carried in bloodstream throughout the body ▪ Systemic infection causes fever, abscesses, sepsis, and shock, often with little or no diarrhea ▪ Peyer's patches sometimes destroyed, leading to rupture of intestine, hemorrhage, and death ▪ Toxin produced when cells are within a host cell ▪ Role of toxin in disease under study Epidemiology ▪ Humans only known host, so spread person to person often via contaminated food or water ▪ Some survivors remain colonized in gallbladder; can shed high numbers for years (for example, "Typhoid Mary") Treatment and prevention ▪ Antibiotics; some strains resistant ▪ Surgical removal of gallbladder and months of antibiotic therapy often necessary to rid carriers of infection ▪ Two vaccines against Salmonella Typhi, each approximately 50 to 75% effective: attenuated live oral or injectable capsular polysaccharide ▪ No vaccine against Salmonella Paratyphi

Haemophilus

Facultative anaerobes. Commonly include the potential pathogen H. influenza

Staphylococcus

Facultative anaerobes. Potential pathogen Staphylococcus aureus commonly inhabits the nostrils

Acute necrotizing ulcerative gingivitis (ANUG)

First called trench mouth, common during World War I Since 2005, increase in ANUG associated with methamphetamine use: "meth mouth" Signs and symptoms •Bleeding painful gums, abscessed and broken teeth, bad breath Causative agent •Polymicrobial infection that includes spirochetes, fusiform, prevotella Pathogenesis • Precise mechanisms of tissue destruction unknown • Plaque always present with large numbers of spirochetes that invade tissue causing necrosis, ulceration • Methamphetamine use lowers saliva production • Tooth grinding increases risk of fracturing teeth Epidemiology • Any age; poor oral hygiene, poor nutrition, high sugar diet, chronic stress, immunodeficiency; methamphetamine use Treatment and prevention • Hydrogen peroxide, antibiotics; removing plaque and tartar • Daily brushing and flossing

Staphylococcus aureus Causes a number of other medical conditions

Food poisoning Intoxication from consuming exotoxin in food Hair follicle infections Folliculitis, carbuncles, furuncles Impetigo Superficial skin disease with pus production Infective endocarditis Infection of heart valves or inner lining of heart Staphylococcal scalded skin syndrome Toxin-mediated skin disease Toxic shock syndrome Superantigens causing low blood pressure and organ failure Wound infections Colonization of wounds; possible systemic complications

Pharynx (Throat) and Epiglottis

From the nose, air moves to the throat (pharynx). Inflammation of the throat, pharyngitis, is commonly the result of viral infection ▪ The throat is shared by the respiratory system and the digestive system

Anatomy, Physiology, and Ecology of the Digestive System

Function of digestive system is to convert foods into absorbable nutrients to use for energy and raw materials for growth ▪ Digestive tract: Hollow tube from mouth to anus ▪ Gastrointestinal tract refers to stomach and intestines ▪ Accessory organs include salivary glands, liver, pancreas ▪ Mucous membrane only one cell layer thick separates microbial population from underlying tissue ▪ Damage allows microbes to penetrate; ingested pathogens often have mechanisms to breach

In which of these organs does a carrier of typhoid bacilli maintain the bacteria?

Gallbladder

Hair Follicle Infections

Generally mild and commonly clear up without treatment. In some instances, however, they progress into severe or even life-threatening disease Signs and Symptoms: There are three outcomes of hair follicle infections, listed by increasing severity: folliculitis, furuncles, and carbuncles. ▪ Folliculitis is inflammation, causes red bumps (pimples) ▪ Infection in adjacent tissues yields a furuncle (boil) ▪ May worsen to form carbuncle, Large area of redness, swelling, pain, draining pus Causative Agent: Staphylococcus aureus; Produces identifying coagulase and clumping factor which are virulence factors Treatment and Prevention: Treatment of boils and carbuncles may require minor surgery to drain the pus from the lesion. Afterward, patients are usually given oral antibiotics

Which of the following is more likely to cause fatal septicemias?

Gram-negative bacteria

A mysterious sequel to Campylobacter jejuni infections is

Guillain-Barré syndrome

The most common bacterial pathogen(s) involved with sinusitis, otitis media, and conjunctivitis is/are

H. influenzae AND S. pneumoniae

Most bacterial intestinal infections may be traced to all of the following EXCEPT

Haemophilus species

Enormous variety of respiratory system infections

Illnesses range from trivial to fatal ❑ Divided into infections of upper respiratory tract (head and neck) and lower respiratory tract (chest) ❑ Upper respiratory infections (for example, colds) very common and uncomfortable, but not life-threatening ❑ Lower respiratory infections (for example, pneumonia, tuberculosis) often serious, may be fatal

Which of the following statements about hepatitis B virus is false?

In the United States, infection rates have been steadily increasing over the last few years

Please choose the statement that best describes staphylococcal scalded skin syndrome (SSSS).

It is an exotoxin-mediated disease characterized by large fluid-filled blisters and peeling skin.

Which of the following statements concerning Salmonella enterica serotype Typhi is false?

It is commonly acquired from domestic animals

Which of the following statements is more likely to be true of measles (rubeola) than of German measles (rubella)?

Koplik spots are present

An important diagnostic sign of measles is

Koplik's spots

Mycoplasmal pneumonia

Leading pneumonia of children, young adults (college students, military recruits). Generally mild; often called "walking pneumonia" or atypical pneumonia Signs and symptoms ▪ Incubation period 2 to 3 weeks. Initial symptoms are sore throat, chills, fever, headache, muscle pain, fatigue ▪ Dry cough after several days; mucoid sputum may be produced later. Some develop otitis media Causative agent: ▪ Mycoplasma pneumoniae, Small bacterium lacking cell wall ▪ Slow, aerobic growth, Colonies on agar look like fried eggs Pathogenesis: ▪ Only a few inhaled cells can start infection. Bacteria attach to receptors on respiratory epithelium. Interfere with ciliary action, cause cells to slough off. Increases chance of secondary infection ▪ Inflammatory response with accumulation of lymphocytes and macrophages thickens walls of bronchial tubes and alveoli

Which S. aureus virulence factor is not correctly matched with its function? α-Toxin—makes holes in host cell membranes. Capsule—avoiding phagocytosis. Protein A—interferes with opsonization. Leukocidin—kills erythrocytes. Hyaluronidase—facilitates spread in tissues

Leukocidin—kills erythrocytes

Which of the following statements about hepatitis is false?

Lifelong carriers of hepatitis A are common

Choose the one true statement about sepsis

Lung damage is an important cause of death

In S. pyogenes, which of the following interferes with phagocytosis?

M protein

Other Fungal Diseases

Malassezia species can cause tinea versicolor and dandruff, as well as serious skin disease in AIDS patients. Candida albicans may live harmlessly among the normal microbiota, but it can invade deeper layers of the skin and subcutaneous.

Norovirus gastroenteritis

Most common cause of viral gastroenteritis in U.S. with about 21 million cases annually ▪ Class B bioterrorism agent due to easy spread Signs and symptoms: Abrupt onset of nausea, vomiting, watery diarrhea Vomiting most severe in older children and adults Causative agent: Noroviruses Non-enveloped, single-stranded RNA viruses in Caliciviridae New strains frequently emergeAt least 5 unrelated viruses can cause hepatitis, an inflammation of the liver Three types (A, B, and C) account for most cases Jaundice (yellowing of skin and whites of eyes) is most noticeable sign Patients should avoid alcohol, acetaminophen, and other chemicals that damage the liver

Bacterial Diseases of the Upper Digestive System Dental caries (tooth decay)

Most common chronic disease; in 60% of U.S. teens Signs and symptoms • Discoloration, roughness, defect; tooth may break • Severe throbbing pain of toothache usually first sign Causative agent • Streptococcus mutans, related Gram-positive cocci are cariogenic (caries generating); live only on teeth, thrive in acidic condition • Produce lactic acid from fermentation Pathogenesis • Streptococci adhere to pellicle on tooth, create plaque • Split sucrose into glucose and fructose; polymerize glucose into glucans and ferment fructose • Lactic acid lowers pH; glucans create thicker biofilm • Following entry of sugar, pH of plaque in mouth drops from about 7 to below 5 in minutes • Plaque can accumulate in fissures or pits in absence of S. mutans Treatment and prevention • Drill out cavity, replace with filling, restore tooth contour • Restrict dietary sucrose, especially frequency and length of time sugary food remains on teeth, Brushing, flossing reduce incidence • Fluoridation in U.S. has reduced dental caries by 60%; Sealant can prevent caries

Impetigo

Most common type of pyoderma, skin infection with pus production Pyodermas can result from infection of an insect bite, burn, scrape, or other wound Causative agent: often Streptococcus pyogenes Gram-positive, chain-forming, group A streptococcus May also be caused by Staphylococcus aureus Pathogenesis ▪ Minor injuries introduce into deeper layer of epidermis ▪ Hyaluronic acid capsule and M protein of cell wall interfere with phagocytosis; additional virulence factors include proteases, nucleases, hyaluronidase ▪ Immune response may produce post-streptococcal sequelae including acute glomerulonephritis Epidemiology ▪ Most common among poor children in hot humid areas ▪ Person-to-person contact, insects, fomites spread Treatment and prevention ▪ S. pyogenes susceptible to penicillin, erythromycin ▪ Wound cleansing, antiseptics, avoiding contact limit spread ▪ Keeping skin clean, avoiding sharing of personal items

Viral Diseases of Lower Digestive System: Intestinal Tract Rotavirus gastroenteritis

Most viral gastroenteritis around the world in infants and children is caused by rotaviruses ▪ Signs and symptoms: abrupt vomiting, slight fever, followed shortly by profuse watery diarrhea ▪ Incubation 24 to 48 hours; usually clears within a week, but fatal dehydration can occur if fluids are not replaced Causative agents: Rotaviruses Non-enveloped with double-walled capsid and double-stranded segmented RNA genome, Major subgroup of Reoviridae Pathogenesis Damages lining of upper small intestine; less fluid absorbed Viral protein acts as enterotoxin Epidemiology Transmitted via fecal-oral route Childhood epidemics; if not vaccinated, most are infected before age 5 Infection yields some immunity; later infections milder

Which of the following statements is true of streptococcal impetigo? It is caused by a Gram-negative rod. It cannot be transmitted from one person to another. Pathogenic streptococci all produce coagulase. All of the above

None of the above

Fusobacterium, Porphyromonas, Prevotella

Obligate anaerobes. Most often found in the space between teeth and gums.

Tuberculosis (TB)

Once very common; incidence declined in industrialized nations as living standards improved Signs and symptoms ▪ Initial infection by Mycobacterium tuberculosis usually results in asymptomatic lung infection. Immune response controls, but unable to eliminate. Slight fever, weight loss, night sweating, persistent cough, often blood-streaked sputum ▪ Yields latent tuberculosis infection (LTBI); later may develop active tuberculosis disease (TB disease), or active tuberculosis ▪ Primarily infects lungs, but bacterial cells can travel through bloodstream to other tissues including kidneys, bones, joints, central nervous system Causative agent: Mycobacterium tuberculosis, Slender, acid-fast, rodshaped bacterium, Strict aerobe with generation time over 16 hours ▪ Unusual cell wall contains mycolic acids: cells resist drying, disinfectants, strong acids and alkali; responsible for acid-fast staining Pathogenesis: ▪ airborne cells inhaled into lungs. Alveolar macrophages quickly engulf; unable to destroy. Mycolic acids prevent fusion of phagosome with lysosomes. Bacteria exit, multiply within macrophage cytoplasm ▪ Pro-inflammatory response recruits more macrophages. Some fuse to form giant multinucleated cells, Others induced by bacteria to accumulate oil droplets, become foamy macrophages ▪ Lymphocytes wall off infected area, granuloma forms,Called tubercles ▪ In granuloma, effector helper T cells release cytokines, Activate macrophages to destroy infecting bacteria ▪ Fibrous layer forms around macrophages, keeps lymphocytes outside of tubercle, Seen on X-rays as Ghon foci ▪ Some bacteria survive; prevented from multiplying (low pH, low O_2). Remain as latent TB infection (LTBI) ▪ In many cases infection resolves ▪ Active TB results if inflammatory response cannot contain or destroy mycobacteria ▪ Macrophages in tubercle die; bacteria, enzymes, cytokines released, forming area of necrosis ▪ Caseous necrosis; foamy macrophages (with lipids) thought to play important role ▪ Tubercle ruptures, releases bacteria, dead material ▪ Causes large lung defect called tuberculous cavity ▪ Spreads bacteria in lungs ▪ Lung cavity persists, enlarges for months or years, spreads bacteria; can be transmitted by coughing Identification of infection ▪ Tuberculin skin test (TST; Mantoux test) ▪ Blood tests (IGRAs) ▪ Xpert MTB/RIF (detect Mycobacterium DNA) Treatment and prevention: Rifampin (RIF), isoniazid (INH), pyrazinamide (PZA), and ethambutol (EMB) given for 8 weeks; then INH, RIF for another 18 weeks Resistant strains often evolve as symptoms disappear, and patient becomes careless in taking medications DOTS (directly observed therapy shortcourse) used Multi-drug-resistant TB (MDR-TB) resists RIF, INH (1990s) Extensively drug-resistant TB (XDR-TB) resists both first and many second-line drugs; threaten global control New medication (bedaquiline) for MDRTB in 2012

Pathogenesis of conjunctivitis

Organisms from airborne respiratory droplets or contaminated hands • Resist destruction by lysozyme • Attachment sometimes aided by degradation of mucin (protective component of epithelial surface mucous) • Release tissue-damaging enzymes and sometimes toxins

S. pneumoniae and H. influenzae frequently cause which of the following?

Otitis media and conjunctivitis

Warts

Papillomaviruses infect skin via minor abrasions ▪ Warts are small benign tumors (papillomas) consisting of protrusions of tissue covered by skin or mucous membrane ▪Papillomaviruses; non-enveloped, double-stranded DNA viruses

Inhalation anthrax

Primarily a disease of livestock; but Bacillus anthracis is also a Category A bioterrorism agent Signs and symptoms ▪ Begins with flu-like symptoms in 1 week to 2 months. Followed by fever, shortness of breath, chest pain, possibly cyanosis ▪ Anthrax meningitis occurs in about half the cases Causative agent: Bacillus anthracis ▪ Endospore-forming, Gram-positive, non-hemolytic, non-motile, rod-shaped bacterium. Vegetative cells have capsule composed of amino acid polymer Pathogenesis ▪ Endospores inhaled, taken up by macrophages, and carried to lymph nodes in chest where they germinate ▪ Anthrax toxin composed of three proteins; results in pulmonary edema and cell death i)Protective antigen (PA) ii)Edema factor (LF) iii) Lethal factor (LF). Toxin-producing, encapsulated cells enter bloodstream, overwhelm defenses, damage tissues Signs and symptoms Fever, nonproductive cough; progressing to shortness of breath, chest pain; meningitis in about 50% of cases Incubation period 3 to 60 days Causative agent Bacillus anthracis, an endospore-forming Grampositive rod Pathogenesis Endospores engulfed by macrophages in lung germinate and produce toxins that kill macrophages, cause pulmonary edema, and damage respiratory cells. Epidemiology Rare zoonotic disease that may be transmitted by animals or animal products; no human transmission; possible agent of bioterrorism. Treatment and prevention Treatment: antimicrobial medications; monoclonal antibody that binds to PA. Prevention: vaccinate livestock; acellular vaccine given to at-risk groups and military.

In which of the following does a rash start on the palms and soles and progress toward the trunk?

Rocky Mountain spotted fever

Which of the following pairs is mismatched? Black escher - cutaneous anthrax Rubella - Koplik spots Exfoliatin - strains of S. aureus Rocky Mountain spotted fever - zoonosis Rubella - prevented by an attenuated vaccine

Rubella - Koplik spots

The principal cause of dental caries is

S. mutans

In addition to S. aureus, impetigo may also involve

S. pyogenes

Strep throat (streptococcal pharyngitis) is caused by

S. pyogenes group A

Where in the body does the latent, non-infectious, non-replicating form of the herpes simplex virus persist?

Sensory nerves

Cholera

Seven pandemics have occurred since early 1800s ▪ South America was cholera-free for 100 years until 1991 when an outbreak occurred in Peru ▪ Lima's water supply was not chlorinated; in 2 years, more than 700,000 cases, 6,323 deaths in South and Central America ▪ In 2011 Haiti had the most recorded cases in country in single year Signs and symptoms ▪ Incubation period of 12 to 48 hours ▪ Classic example of severe watery diarrheal disease ▪ "Rice water stool" appearance; dehydration can lead to organ failure Vomiting may occur at onset; severe muscle cramps result from loss of fluids and electrolytes Causative agent: Vibrio cholerae ▪ Curved, Gram-negative rod; Several serotypes grouped by O antigen ▪ O1 serotype is pandemic; O139 in Asia ▪ Halotolerant, can grow in alkaline conditions Pathogenesis ▪ Sensitive to acid, so large numbers must be ingested ▪ Adhere to epithelial cells of small intestine, establish infection, produce cholera toxin, an A-B toxin. B portion attaches to receptors of microvilli; A portion enters cells, activates a G protein that turns on adenylate cyclase to convert ATP to cAMP. ▪ High cAMP causes cell to secrete chloride ions, Sodium and other ions follow, and water follows the salts, yielding, outpouring from cells. Toxin does not affect large intestine, but volume of fluid is too much to be absorbed, causing diarrhea ▪ Toxin encoded by bacteriophage: lysogenic conversion Epidemiology ▪ Fecally contaminated water most common source ▪ Foods including crab, oysters, vegetables implicated Treatment and prevention ▪ Intravenous or oral rehydration therapy can decrease mortality ▪ Clean water and adequate sanitation are key control measures ▪ Vaccines available in many parts of world

Adenovirus Respiratory Tract Infections

Signs and Symptoms Fever, sore throat, cough, swollen lymph nodes of neck, pus on tonsils and throat Incubation period 5 to 10 days' Causative agent Adenoviruses—more than 50 serotypes— non-enveloped, double-stranded DNA genome Pathogenesis Virus multiplies in host cells; cell destruction and inflammation occur; different serotypes produce different symptoms. Epidemiology Inhalation of infectious droplets; possible spread from gastrointestinal tract. Treatment and prevention Treatment: no treatment except for control of symptoms. Prevention: handwashing, avoiding crowds.

Streptococcal Pharyngitis ("Strep Throat")

Signs and symptoms ▪ Sore throat, difficulty swallowing, fever ▪ Throat is red with patches of pus, tiny hemorrhages ▪ Causative agent is Streptococcus pyogenes, Gram-positive; grows in chains, βhemolysis of blood agar ▪ Group A streptococcus (GAS) from Lancefield grouping ▪ Different strains within GAS distinguished by M protein

Rocky Mountain Spotted Fever

Signs and symptoms ▪ Sudden headache, pain in muscles and joints, fever ▪ Flat pink rash first appears on wrists, ankles spreads up arms and legs to rest of body ▪ Rash on palms and soles (not typical) ▪ In about half of cases, petechiae (purplish spots) form due to small hemorrhages under skin ▪ Damage to heart, kidneys, brain, other tissues can lead to drop in blood pressure, shock, and death without prompt treatment Causative agent: Rickettsia rickettsii ▪ Tiny Gram-negative non-motile coccobacilli ▪ Obligate intracellular bacteria; difficult to grow in culture ▪ May be identified by skin lesion biopsies, or PCR amplification followed by probe Pathogenesis ▪ Transmitted by tick bite after 4 to 10 hours of feeding ▪ Bacteria taken up by endothelial cells lining small blood vessels ▪ Bacteria leave phagosome; multiply within cell ▪ Bacteria use host actin to form "actin tail" to move into adjacent host cells; cause extensive membrane damage ▪ Cells rupture, release rickettsias into bloodstream ▪ Inflammation in blood vessels leads to clotting, small areas of necrosis, hemorrhagic skin rash, tissue damage ▪ Release of endotoxin into bloodstream causes shock, disseminated intravascular coagulation (DIC) Epidemiology ▪ Sporadic distribution throughout the Americas ▪ Zoonosis maintained in various species of ticks, mammals ▪ Humans are accidental host; develop severe disease ▪ Major vectors: wood tick, dog tick; active April to Sept. Treatment and prevention ▪ Doxycycline effective if given prior to irreversible organ damage ▪ Case-fatality rate approximately 20% without treatment, below 5% with ▪ No vaccine, but precautions against tick bites can limit transmission

Hantavirus Pulmonary Syndrome

Signs and symptoms Fever, muscle aches, vomiting, diarrhea, cough, shortness of breath, shock Incubation period 3 days to 6 weeks Causative agent Sin Nombre and related hantaviruses; enveloped viruses with segmented single-stranded RNA Pathogenesis Viral antigen localizes in capillary walls in the lungs; inflammation. Epidemiology Zoonotic disease; epidemics associated with increases in mouse populations near housing; generally no person-toperson spread. Treatment and prevention Treatment: no antiviral treatment. Prevention: avoiding contact with rodents; sealing access to houses, food supplies; good ventilation; avoiding dust; using disinfectants in cleaning rodent-contaminated areas.

Fungal Infections of the Lung Pneumocystis Pneumonia (PCP)

Signs and symptoms Gradual onset, shortness of breath, rapid breathing, nonproductive cough, slight or absent fever, and dusky color of skin and mucous membranes Incubation period 4 to 8 weeks Causative agent Pneumocystis jirovecii (previously known as P. carinii)—a fungus Pathogenesis Inhaled fungal cells attach to alveolar walls, causing alveoli to fill with fluid, macrophages, and fungal cells. Alveolar walls thicken, impairing O2 exchange. Epidemiology Most humans become infected in early childhood—source of human infections is unknown. Epidemics can arise in immunodeficient groups. Treatment and prevention Treatment: antimicrobial medications. Prevention: prophylactic doses to those with AIDS of the

Viral Infections of the Upper Respiratory System-The Common Cold

Signs and symptoms Malaise, runny nose, sneezing, cough, sore throat, hoarseness Incubation period 1 to 2 days Causative agent Mainly rhinoviruses—more than 100 types; many other viruses; some bacteria Pathogenesis Viruses attach to respiratory epithelium; ciliary action stops, and cells slough; secretion of mucus increases, and inflammatory reaction occurs. Epidemiology Inhalation of infectious droplets; transfer of infectious mucus to nose or eye by contaminated fingers. Treatment and prevention Treatment: no treatment except for control of symptoms. Prevention: handwashing, avoiding people with colds, and keeping hands away from face.

Respiratory Syncytial Virus (RSV) Infections

Signs and symptoms Runny nose, cough, fever, wheezing, difficulty breathing, bluish color Incubation period 1 to 4 days Causative agent Respiratory syncytial virus (RSV), a paramyxovirus that produces syncytia Pathogenesis Sloughing of respiratory epithelium and inflammatory response plug bronchioles, cause bronchiolitis; pneumonia from bronchiolar or alveolar inflammation; secondary infection. Epidemiology Yearly epidemics during the cool months; readily spread by otherwise healthy older children and adults with mild symptoms; no lasting immunity. Treatment and prevention Treatment: no satisfactory antiviral treatment. Prevention: no vaccine. For high-risk individuals, passive immunization with immune globulin or a monoclonal antibody

Diphtheria is deadly toxin-mediated disease

Signs and symptoms Sore throat, fever, fatigue, and malaise; pseudomembrane forms on tonsils and throat or in nose; paralysis, heart and kidney failure Incubation period 2 to 6 days Causative agent Corynebacterium diphtheriae, an A-B toxin- producing, non-spore-forming Gram-positive rod Pathogenesis Infection in upper respiratory tract; exotoxin is released and absorbed by bloodstream; toxin kills cells by interfering with protein synthesis; affects cells that have receptors for the toxin—mainly heart, kidney, and nerve tissue. Epidemiology Inhalation of infectious droplets; indirect contact with fomites. Treatment and prevention Treatment: antitoxin; appropriate antibiotic to prevent transmission. Prevention: immunization of infants and children with toxoid; boosters for adults.

Clostridium difficile Infection (CDI)

Signs and symptoms Variable; mild diarrhea to pseudomembranous colitis, a potentially fatal inflammation of the colon Incubation period Usually less than a week Causative agent Clostridium difficile, a Gram-positive, rod-shaped, endospore-forming anaerobe Pathogenesis Toxins disrupt host cell actin and cell signaling, causing lethal effects to the intestinal epithelium. Epidemiology Primarily occurs in patients on antibiotic therapy. Treatment and prevention Treatment: when practical, stop antimicrobial medications; otherwise, an antimicrobial medication that targets C. difficile. Fecal transplant to restore normal intestinal microbiota. Prevention: includes handwashing and disinfection of surfaces.

Hepatitis B (formerly, serum hepatitis)

Signs and symptoms ▪ Acute form ranges from asymptomatic to severe ▪ Incubation varies from 2 to 5 months depending on dose ▪ Acute disease rarely fatal; virus usually cleared within weeks or months of initial infection ▪ Can become chronic; one in five develop cirrhosis (scarring of the liver), liver failure, liver cancer, or other chronic liver disease ▪ Causative agent: Hepatitis B virus (HBV) ▪ Enveloped, mostly double-stranded DNA genome ▪ Resistant; virions infectious after a week outside the body ▪ Member of Hepadnaviridae ▪ Three notable components serve as useful markers ▪ Hepatitis B surface antigen (HBsAg) ▪ Appear in bloodstream before signs of liver damage are evident ▪ Hepatitis B core antigen (HBcAg) ▪ Indicate active viral replication ▪ Hepatitis B e antigen (HBeAg) ▪ Correlate with increased risk of liver damage and risk of spread ▪ Complete virion is Dane particle; less common than empty envelopes with HBsAg but no DNA Pathogenesis Bloodstream carries to liver; HBsAg allows virus to attach Replication involves HBV-encoded reverse transcriptase Liver damage likely from cell-mediated immune response Epidemiology ▪ Transmitted in body fluids (saliva, blood, blood products, semen); activities that mix fluids are risk factors ▪ Sharing needles, toothbrushes, razors, towels, unsterile tattooing or ear-piercing instruments ▪ About half of new cases in U.S. from unprotected sex ▪ In chronic infection, virus replicates and circulates in blood for years, often asymptomatically, which increases spread Treatment and prevention ▪ No curative antiviral treatment, but PEP with hepatitis B immune globulin (HBIG) or vaccination can protect ▪ Reverse transcriptase inhibitors plus interferon injections ▪ First vaccine approved in early 1980s, consisted of HBsAg from blood of chronic carriers ▪ Since 1986, genetically engineered subunit vaccine available, given to all newborns before leaving hospital ▪ Combined vaccine against hepatitis A and B

Hepatitis A (formerly, infectious hepatitis)

Signs and symptoms ▪ Acute illness; no known chronic form or carrier state ▪ Older children and adults develop jaundice, fever, fatigue, claycolored feces, and vomiting after approximately 1 month incubation ▪ Most young children (<6 years) and many older children (6 to 14 years) are asymptomatic ▪ About 1 in 5 adults requires hospitalization Causative agent: Hepatitis A virus (HAV) Non-enveloped single-stranded RNA virus of Picornaviridae Pathogenesis Following ingestion, reaches liver via unknown route Replicates, is released into bile, eliminated in feces Epidemiology Spreads via fecally contaminated hands, food, or water Many outbreaks traced to restaurants where food-handlers failed to wash hands. Raw shellfish may be source; virus is concentrated from fecally polluted seawater High risk groups: children in day care centers, residents in nursing homes, international travelers, individuals having sexual contact with infected person Treatment and prevention No antiviral treatment available, but post-exposure prophylaxis (PEP) can prevent disease if given within 2 weeks of exposure Immune globulin provides immediate but short-term protection Vaccination provides long-term protection in those who develop adequate response to vaccine. Effective inactivated HAV vaccine recommended for all children 1 to 2 years of age

Viral Diseases of the Upper Digestive System Oral herpes simplex (cold sores; fever blisters)

Signs and symptoms ▪ Fever, small blisters in mouth that break in a day or two; produce painful superficial ulcers (incubation 2 to 20 days) ▪ Lesions heal within approximately 10 days, but virus persists ▪ Recurrent cold sores usually less severe ▪ Tingling, itching, burning; blisters, ulcerations usually heal within 7 to 10 days Causative agent: Herpes simplex viruses (HSVs) ▪ Enveloped viruses with double-stranded linear DNA ▪ Two types: HSV-1 (most oral infections) and HSV-2 (usually genital infections) Pathogenesis ▪ Virus multiplies in epithelium, destroys cells. Some cells fuse to produce multinucleated giant cells, where viruses replicate ▪ Viral DNA persists in nerve cells in latent form ▪ Stresses can reactivate (menstruation, sunburn, fever) Epidemiology ▪ Initial infection during childhood; symptoms usually mild ▪ Virus transmitted by close contact, but transmission by fomites such as plastic and cloth is possible ▪ Greatest risk is contact with lesions or saliva within few days of disease onset since many virions present ▪ HSV can infect almost any body tissue ▪ Herpetic whitlow (finger infection) ▪ Blindness can result if rubbed into the eyes Treatment and prevention ▪ Medications like acyclovir target HSV DNA polymerase. Do not affect latent virus and so cannot cure ▪ Sunlight can trigger, so sunscreens useful as preventive

Shigellosis

Signs and symptoms ▪ Incubation period 1 to 3 days ▪ Usually dysentery, some species cause watery diarrhea ▪ Headache, vomiting, fever, stiff neck, convulsions, joint pain ▪ Often fatal for infants in developing countries Causative agents ▪ Four species of Shigella, Gram-negative rods: S. dysenteriae, S. flexneri, S. boydii, and S. sonnei ▪ S. dysenteriae most virulent, S. sonnei least virulent ▪ S. dysenteriae and S. flexneri most common in developing countries ▪ S. sonnei causes over two-thirds of cases in U.S. Pathogenesis ▪ Shigella taken up using antigen sampling function of M cells ▪ Multiply inside macrophages, released at bases of epithelial cells after macrophages die ▪ Attach to specific receptors, induce uptake by epithelial cells, multiply, cause actin polymerization to propel cell to cellInvasion results in death of epithelial cells, sloughing of patches of epithelium; strong inflammatory response ▪ Some strains produce Shiga toxin, an A-B toxin responsible for hemolytic uremic syndrome (HUS) ▪ B subunit binds to endothelial cells lining small blood vessels ▪ A subunit halts protein synthesis, leading to cell death ▪ HUS may cause anemia and kidney failure; often fatal Epidemiology ▪ Disease of humans; fecal-oral route ▪ Small infectious dose; Shigella resistant to stomach acid ▪ Spreads rapidly in populations with poor sanitation Treatment and prevention ▪ Antimicrobials shorten duration; some strains resistant ▪ Sanitary measures control spread ▪ Cases can be tracked through PulseNet

Mumps

Signs and symptoms ▪ Onset marked by fever, loss of appetite, headache; incubation 15 to 21 days ▪ Followed by painful swelling of one or both parotid glands ▪ Spasm of underlying muscle makes talking, chewing hard; Serious consequences most likely in elderly ▪ Headache, stiff neck indicate of meningitis ▪ Pregnant women often miscarry ▪ Sudden-onset deafness ▪ Orchitis is swelling of testicles; Ovarian involvement is manifested by pelvic pain Causative agent: Mumps virus ▪ Enveloped, single-stranded RNA virus of Paramyxoviridae Pathogenesis ▪ Virus inhaled via saliva droplets, spreads via bloodstream. ▪ Virus multiplies in epithelium of ducts; In parotid salivary glands, inflammatory response yields severe swelling, pain ▪ Similar process in tubules of testicles or kidneys. Swelling can impair blood supply to testicular tissue Treatment and prevention No effective treatment. Attenuated vaccine as part of measles, mumps, rubella (MMR), and varicella (MMRV) vaccine

Hepatitis C

Signs and symptoms ▪ Similar to A and B except generally milder; incubation period about 6 weeks (2 weeks to 6 months) ▪ Approximately 65% of individuals have no symptoms of acute infection, only approximately 25% have jaundice ▪ >80% develop chronic infection; related to cirrhosis, liver cancer Causative agent: Hepatitis C virus Enveloped, single-stranded RNA virus of Flaviviridae, first cultivated in vivo in 2005. Much genetic variability; types differ in pathogenicity Pathogenesis Infection generally from exposure to contaminated blood Disease process starts and stops Hepatitis A Hepatitis B Hepatitis C Causative agent Non-enveloped, single-stranded RNA picornavirus, HAV Enveloped, doublestranded DNA hepadavirus, HBV Enveloped, singlestranded RNA flavivirus, HCV Transmissi on Fecal-oral Blood, semen Blood, possibly sems Incubation period 3 to 5 weeks (range, 2 to 7 weeks) 10 to 15 weeks (range, 6 to 23 weeks) 6 to 7 weeks (range, 2 to 24 weeks) Prevention Inactivated vaccine; immune globulin Subunit vaccine; hepatitis B immune globulin (HBIG) No vaccine Comments Usually mild symptoms, but often prolonged; full recovery; no chronic carriers; combined hepatitis A and B vaccine available Acute symptoms often more severe than in hepatitis A; chronic disease can lead to cirrhosis and cancer; chronic carriers; can cross the placenta; combined hepatitis A and B vaccine available Usually few or no symptoms; progressive liver damage can lead to cirrhosis and cancer; chronic carriers; highly effective treatments are newly available

Focus on Diarrheal Diseases Gastroenteritis; "stomach flu" (not influenza)

Signs and symptoms: ▪ Diarrhea, loss of appetite, nausea, vomiting, perhaps fever; incubation period 1 to 2 days ▪ Small intestine infection: abundant, watery diarrhea ▪ Large intestine infection: small amounts of diarrhea with mucus, pus, and sometimes blood ▪ Dysentery: blood and pus in feces Pathogenesis ▪ Virulence genes often shared by horizontal transfer ▪ Acid tolerance; organism must survive passage through stomach ▪ Disrupts fluid exchange in small intestine; can result in dehydration ▪ Causes strong inflammatory response in large intestine ▪ Mechanisms include alteration of intestinal epithelial cells, cell invasion, exotoxin production ▪ Enterotoxins cause water and electrolyte loss; Cytotoxins cause cell death; Some absorbed into bloodstream; systemic effects Epidemiology ▪ Hundreds of thousands of children die of diarrheal disease every year; most are infants ▪ Transmitted by fecal-oral route ▪ Ingestion of contaminated food, water ▪ Sexual practices with oral-anal contact ▪ Pathogens with low infectious dose can be transmitted by person-toperson contact ▪ Sewage treatment, handwashing, chlorination of drinking water are important control measures Treatment and prevention ▪ Oral rehydration therapy (ORT): appropriate fluids counteract loss of fluid and electrolytes ▪ Glucose increases absorptive capacity of intestine. ORS is mixture of glucose and salts; premeasured packets added to clean water ▪ Antimicrobial medications often prolong bacterial infection as they suppress normal microbiota; zinc supplements may decrease severity of disease. A few pathogen-specific vaccines are available

Staphylococcal Scalded Skin Syndrome

Staphylococcal scalded skin syndrome (SSSS) is a potentially fatal, toxin-mediated disease that occurs mainly in infants. Signs and Symptoms: ▪ Begins as redness of skin, malaise, irritability, fever ▪ Nose, mouth, genitalia may become painful ▪ Within 48 hours of redness, skin wrinkles and peels as large fluidfilled blisters develop Causative Agent ▪ Staphylococcus aureus ▪ 5% of strains that produce toxin called exfoliatin Destroys material that binds outer layers of epidermis Pathogenesis epidermis splits below dead layer ▪ Exfoliatin carried in blood, widespread areas lose skin ▪ Fluid loss, risk of secondary infection Epidemiology: any age group; most frequently newborns ▪ Transmission generally person-to-person Treatment and prevention: antibiotics, dead skin removal Can be fatal; quick treatment usually yields full recovery

Which of the following are bacterial diseases of the upper respiratory tract?

Streptococcal pharyngitis and diphtheria

The cause of strep throat is

Streptococcus pyogenes—beta-hemolytic, group A

Which of the following statements about brucellosis is false?

The causative agent is readily killed by phagocytes

Which of these statements about tularemia is false?

The causative organism has growth requirements similar to those of E. coli.

Which of the following statements about malaria is true?

The characteristic recurrent fevers are associated with release of merozoites from RBCs

Anatomy, Physiology, and Ecology of the Respiratory System

The major function of the respiratory system is gas exchange. ❑ Each breath brings in O2 , which replenishes the supply in the blood, and then releases CO2 , the waste product of cellular metabolism. ❑ In addition, movement of air over the vocal cords makes sound, which allows us to speak, and sensors in the nose detect odors. ❑ The respiratory system consists of the upper respiratory tract and the lower respiratory tract.

Importance of skin

The skin is a barrier that prevents the entry of microbes, regulates body temperature, and restricts the loss of fluid from body tissues It has many sensory receptors that provide the central nervous system with information about the environment The skin also plays an essential role in the function of the immune system Collections of lymphocytes found in skin-associated lymphoid tissues (SALT) are ready to proliferate when needed Skin is a distinct ecological habitat, most areas of the skin are cool and dry. Members of the normal skin microbiota are uniquely suited to thrive in this environment Most of the microbial skin inhabitants can be categorized in three groups: diphtheroids [Gram-positive rods of the Cutibacterium and Corynebacterium genera], staphylococci [Gram-positive cocci] , and fungi [require oily substances for growth]

Anatomy, Physiology, and Ecology of the Skin

The skin is composed of two layers: the epidermis and the dermis. The subcutaneous layer, or hypodermis, lies beneath the dermis and supports the skin The outermost layers of skin are bathed in secretions produced by glands in the dermis Sweat glands produce sweat Sebaceous glands produce the oily secretion called sebum

The Upper Respiratory Tract

The upper respiratory tract includes the nose and nasal cavity, pharynx ▪ Mucous membranes line the respiratory tract; produced by goblet cells ▪ Ciliated epithelium lines ▪ mucociliary escalator, is an important defense that helps prevent microorganisms that have been inhaled from reaching the lungs. ▪ The tonsils are lymphoid organs

Which of the following statements about yellow fever is false?

There is no animal reservoir

Which of the following about intestinal bacteria is false?

They are mostly aerobes

Which of the following statements about noroviruses is false?

They generally cause vomiting lasting 1 to 2 weeks

Which of the following is NOT true about diphtheroids?

They include Malassezia species

The Nose and Nasal Cavity

This warms the air in the nose to near body temperature while passage over mucous membranes saturates it with water vapor

Otitis media is an infection of the middle ear that is rare in the first month of life

True

Which of the following are considered diseases of the lower respiratory tract?

Tuberculosis and pneumonia

SARS and MERS

Two novel coronaviruses caused new diseases ▪ Severe acute respiratory syndrome (SARS) seen in 2003 involved 27 countries resulting in over 8000 cases and 800 deaths ▪ Middle East respiratory syndrome (MERS) seen in 2012 involved more than 25 countries by 2016 resulting in over 1800 cases and 600 deaths Signs and symptoms ▪ Typical flu-like symptoms of fever, malaise, muscle aches, nonproductive cough, shortness of breath (incubation period 2 to 7 days) ▪ Many develop pneumonia Causative agents ▪ SARS coronavirus (SARS-CoV) and MERS coronavirus (MERSCoV) of Coronaviridae ▪ Enveloped, single-stranded RNA viruses with spikes on surface, giving crown-like appearance Pathogenesis ▪ Infect cells in lower respiratory tract and replicate genome within virus-induced vesicles that hide them from host responses ▪ Damages cells and strong immune response ▪ Cytokine storm Epidemiology: ▪ zoonotic viruses; likely originated in bats ▪ Transmitted by respiratory droplets during close person-toperson contact

Viral Diseases of the Skin Varicella (Chickenpox)

Varicella-zoster virus from respiratory secretions or Skin lesions is inhaled; infects nose and throat. 2.The virus infects nearby lymph nodes, reproduces, and enters the bloodstream. 3.Infection of other body cells occurs, resulting in spread of virions into the bloodstream. 4. Virions cause successive skin lesions, which evolve into blisters and crusts. 5.If immunity decreases, latent virus persisting in sensory nerve ganglia can reactivate and return to the skin, causing shingles. 6.Transmission occurs from respiratory secretions or skin lesions, causing chickenpox in people not immune to VZV. Signs and symptoms Itchy bumps and blisters in various stages of development, fever; latent infections can reactivate, resulting in shingles. Incubation period 10 to 21 days Causative organism Varicella-zoster virus; enveloped double-stranded DNA herpesvirus. Pathogenesis Virus enters respiratory tract, replicates in lymph nodes, spreads via bloodstream to the skin and forms lesions; infected cells fuse, swell, and then lyse. Epidemiology Highly infectious. Acquired by the respiratory route; people infected with either chickenpox or shingles are the only source; spread via skin lesions and respiratory secretions. Treatment and prevention Treatment: antiviral medication. Prevention: attenuated vaccine (single agent or in the combination MMRV); passive immunization with zoster immune globulin for immunocompromised individuals

Epidemiology

Virulence of bacteria, crowding of potential hosts, presence of respiratory viruses all likely important, Nasal allergies, air pollution, smoking may play role • Preceding or concurrent viral illness is common, Virus may damage protective mucociliary mechanisms • Otitis media rare in first month of life, but common in early childhood; increased risk from pacifiers beyond age two; older children develop immunity so rare beyond age five • Sinusitis tends to affect adults and older children with more developed sinuses

Helicobacter pylori is able to survive in the stomach by its ability to produce

ammonia from urea

Part of the ability of S. mutans to result in dental caries depends on its ability to

convert sucrose to lactic acid

The food products most commonly contaminated with Salmonella strains are

eggs and poultry

Diphtheria toxin works on

elongation factor 2

The principal species of Staphylococcus found on the skin is

epidermidis

The surface layer of the skin is the

epidermis

Which species of Plasmodium causes the most serious form of malaria?

falciparum

The plague is typically transmitted via the bite of

fleas

The malarial form infectious for mosquitoes is called a

gametocyte

Rebecca Lancefield showed that almost all the strains of beta-hemolytic streptococci from human infections

had the same cell wall carbohydrate "A."

Shigella and cholera toxin both

have an A-B arrangement

Projecting from the outer envelope of the influenza virus are two glycoproteins called

hemagglutinin and neuraminidase

In the United States, hantaviruses

infect human beings with a fatality rate of about 30%

The spleen enlarges in

infectious mononucleosis AND malaria

The main effect of staphylococcal protein A is to

interfere with phagocytosis

Yops, proteins produced by Yersinia pestis

interfere with phagocytosis

The fluid which bathes and nourishes the tissue cells is the

interstitial fluid

Respiratory syncytial virus

is a leading cause of serious lower respiratory tract infections in infants

The disease histoplasmosis

is a threat to AIDS patients living in areas bordering the Mississippi River.

Helicobacter pylori has all of the following characteristics except

it has not been cultivated in vitro

All are true of mycoplasmal pneumonia except

it is a mycosis

All of the following are true of coccidioidomycosis except

it is more common in Maryland than in California

All of the following attributes of Streptococcus mutans are important in tooth decay except

it produces endotoxin, which triggers an inflammatory response

All of the following are true of legionellosis except

it spreads readily from person to person

The MMR vaccine is used to protect against

measles, mumps, rubella

The viral disease that characteristically infects the parotid glands is

mumps

The esophagus

muscular tube from mouth to stomach ▪ Peristalsis pushes food toward stomach

Mycoplasmal pneumonia is different from pneumococcal pneumonia in that

mycoplasmal pneumonia cannot be treated with penicillin.

The preferred habitat of S. aureus is the

nasal chamber

Otitis media and sinusitis are usually preceded by a(n)

nasopharyngeal infection

Viral gastroenteritis that affects people of all ages and usually lasts less than 3 days is caused by

norovirus

Although unusually resistant to many control factors, the tubercle bacillus is easily killed by

pasteurization

The sac which surrounds the heart is called the

pericardium

The chronic inflammatory process involving the gums and tissues around the teeth is called

periodontal caries

The initial attachment required for establishment of an intestinal infection is by

pili

Most colds are probably caused by

rhinovirus

The heart chamber that passes blood to the lungs is the

right ventricle

The oily secretion that lubricates the hair follicles of the skin is

sebum

The rubeola virus contains

single-stranded RNA

All of the following are true of Rocky Mountain spotted fever except

the disease is most prevalent in the western United States

Hepatitis A spreads via

the fecal-oral route

Rubella, rubeola, and varicella-zoster are all only acquired via

the respiratory route

The eyes are protected from infection by

the washing action of the tears and eyelids AND the chemical action of lysozyme

Yersinia pestis typically contains

three plasmids

The main vector(s) of Rocky Mountain spotted fever in the western United States is/are

ticks

The vaccine for preventing diphtheria contains ______, while that for preventing pneumococcal pneumonia contains ______.

toxoid; capsular polysaccharides

Enlargement of lymph nodes or spleen is often associated with

tularemia, brucellosis, AND plague

Antigenic shifts may be the result of

two different viruses infecting a cell at the same time

The liver:

upper right portion of abdomen • Produces bile, stored in gallbladder; released into upper intestine • Severe liver disease or obstruction of bile ducts can cause jaundice, yellow color of skin and eyes from buildup of bilirubin in blood • Inactivates toxic substances (for example, ammonia, medications)

All of the following might contribute to development of ringworm or other superficial cutaneous mycoses except

using skin powder

A common viral rash of childhood with the popular name chickenpox is also known as

varicella-zoster

Cholera is the classic example of a(n)

very severe form of diarrhea

The disease caused by an enveloped single-stranded RNA arbovirus of the flavivirus family is

yellow fever

Which of the following are transmitted by mosquitoes?

yellow fever AND malaria