Gram-negative — Flashcards

Flashcard 41: What are the three general mechanisms of bacterial endotoxin action?

Answer: activate macrophages activate complement activate tissue factor

Flashcard 42: What is the most well-known bacterial endotoxin?

Answer: lipid A of LPS

Flashcard 43: Mechanism and source of Cholera toxin?

Answer: Produced by Vibrio cholerae (causes rice-water diarrhea)

Extra: Permanently activates Gs protein → overactivates adenylate cyclase → ↑ cAMP → increased Cl- secretion into gut lumen → voluminous "rice-water" diarrhea.

Flashcard 44: Heat-stable enterotoxin (ST) is produced by?

Answer: Enterotoxigenic E. coli (ETEC)

Extra: Mechanism: Overactivates guanylate cyclase → increases cGMP → decreased NaCl and water resorption (leads to watery diarrhea). Mnemonic: Labile in the Air (cAMP), Stable on the Ground (cGMP).

Flashcard 45: heat-labile toxin (HLT)

Answer: enterotoxigenic E. coli

Extra: increases fluid secretionsoveractivates adenylate cyclase, increased Cl- secretion mnemonic: labile in the Air, stable on the Ground watery diarrhea

Flashcard 46: exotoxin A (P. aer)

Answer: Pseudomonas aeruginosa

Extra: protein synthesis inhibitorinactivates elongation factor 2 (EF-2)host cell death

Flashcard 47: Give some diseases caused by endotoxins.

Answer: meningococcemia, sepsis by G- rods

Flashcard 48: What are the modes of action of bacterial endotoxins?

Answer: induce TNF and IL-1

Flashcard 49: What are the clinical effects of bacterial endotoxins?

Answer: fever, shock

Flashcard 50: How can Legionella be visualized microscopically?

Answer: silver stain

Extra: Legionella is a thin Gram-negative rod that stains poorly on Gram stain; it is visualized using silver stains (e.g., Dieterle stain) or direct fluorescent antibody (DFA).