Toxin Tactics
Cholera toxin, ETEC’s heat-labile toxin, and one of the B. cereus toxins all act through this shared mechanism, raising this second messenger in intestinal cells.
What is cAMP (causing hypersecretion of fluid and electrolytes)?
A child has a sore throat, fever, and a flushed, sandpaper-like rash. Name the disease and the toxin responsible.
What are scarlet fever and pyrogenic (erythrogenic) exotoxin?
Green pus with a fruity odor from a burn wound points to this organism and its two pigments.
What are Pseudomonas aeruginosa, pyocyanin, and pyoverdin?
Mycobacteria stain weakly with the Gram stain and are acid-fast because of these cell wall lipids.
What are mycolic acids (waxes/glycolipids)?
A cat bite causes redness, swelling, and pain within hours. Name the most common organism isolated from such wounds.
What is Pasteurella multocida?
TSST-1 from S. aureus and the pyrogenic exotoxin from group A strep both cause shock by acting as this, massively stimulating T-cells.
What is a superantigen?
Weeks after a family eats improperly cooked home-canned vegetables, they develop flaccid paralysis. Name the organism and the neurotransmitter its toxin blocks.
What are Clostridium botulinum and acetylcholine?
An elderly, debilitated patient has necrotizing lobar pneumonia with thick, red “currant jelly” sputum. Name the organism and its main virulence feature.
What are Klebsiella pneumoniae and its large, gelatinous capsule?
M. tuberculosis has no toxins and no capsule, but this surface lipid, trehalose-6,6'-dimycolate, inhibits leukocyte migration and causes chronic granulomas.
What is cord factor? (serpentine cords)?
A hiker is bitten by an Ixodes tick and develops a flat, round red rash. Name the disease.
What is Lyme disease?
One gram-positive rod colonizing the pharynx and one gram-negative rod in burn wounds and the lungs each produce an exotoxin that inhibits protein synthesis. Name both organisms.
What are Corynebacterium diphtheriae and Pseudomonas aeruginosa?
A trauma patient has necrotic skin, crepitus on palpation, and gas pockets in the muscle on CT. Name the organism and the muscle disease.
What are C. perfringens and clostridial myonecrosis (gas gangrene)?
A military recruit has abrupt high fever, a petechial rash, and hypotension, and dies within hours after hemorrhage into these glands. Name the organism and the glands.
What are Neisseria meningitidis and the adrenal glands?
A leprosy patient has abundant acid-fast bacilli, bacteremia, low cell-mediated immunity, and high humoral immunity. Name the form of disease.
What is lepromatous leprosy?
This long, thin, aerobic spirochete is shed in the urine of rats, dogs, and livestock and causes leptospirosis.
What is Leptospira (L. interrogans)?
A child with Haemophilus influenzae type b meningitis gets worse shortly after antibiotics begin. This is the cause.
What is release of lipid A (endotoxin) from lysed bacteria, causing shock?
A woman using tampons has sudden fever, vomiting, diarrhea, a red rash, peeling skin, and shock. Name the organism and why the tampon contributes.
What are S. aureus and the tampon acting as a blood-rich, warm culture medium, so the toxin crosses the mucosa and stimulates TNF-α and interleukins?
A patient with a long-term urinary catheter develops kidney stones and a swarming organism on the plate. Name the genus and the enzyme that raises urine pH.
What are Proteus and urease?
M. leprae cannot grow on artificial media but can be grown in the footpad of a mouse or in this animal.
What is the nine-banded armadillo?
The flea’s gut blocks after infection with this organism, which produces coagulase at 28°C. Name the organism and the form of its disease with 95% of cases.
What are Yersinia pestis and bubonic plague?
This anthrax component binds the host receptor and forms a seven-subunit “donut” to deliver the toxin that raises cAMP and causes massive edema. Name both.
What are protective antigen and edema factor?
Diarrhea and pseudomembranous colitis develop after a course of broad-spectrum antibiotics. Name the organism, its two toxins, and why it flourishes.
What are C. difficile, toxins A and B, and resistance to broad-spectrum antibiotics (opportunistic overgrowth)?
High fever, delirium, rose spots, and hepatosplenomegaly follow proliferation in Peyer’s patches. Name the organism and its only reservoir.
What are Salmonella typhi and humans?
An AIDS patient has a TB-like disease caused by an environmental organism that is resistant to anti-TB drugs and not readily spread person to person. Name the likely organism.
What is Mycobacterium avium-intracellulare?
Contaminated cooling towers, shower heads, and mist machines spread this organism. Name it and its two disease forms, mild and severe.
What are Legionella pneumophila, Pontiac fever, and Legionnaires’ disease?