Bacteriology USMLE Step 1 Practice Question
A 5-year-old boy presents with fever (39.2°C), abdominal cramping, and small-volume bloody diarrhea after a daycare outbreak. Vital signs show HR 115/min, RR 22/min, BP 100/62 mmHg, and SpO2 98% on room air. Stool culture yields nonmotile gram-negative rods; stool leukocytes are elevated at 15/hpf. Urinalysis shows no hematuria. Which mechanism explains how the responsible organism's toxin produces disease?
Answer choices
- AActivation of adenylate cyclase through Gs
- BCross linking T cell receptor and MHC class II molecules
- CADP ribosylation of elongation factor 2
- DInhibition of acetylcholine release at the neuromuscular junction
- EInactivation of the 60S ribosomal subunitCorrect answer
- FInhibition of Na-K-ATPase pump on intestinal epithelial cells
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