Bacteriology USMLE Step 1 Practice Question
A 67-year-old man presents with fever (39.2°C), hypotension (BP 88/52), and confusion. Blood cultures grow gram-negative rods. On examination, he has warm extremities and tachycardia (HR 118). Serum lactate is elevated at 4.2 mmol/L. He denies recent antibiotic use. Within hours of admission, he develops signs of septic shock with progressive organ dysfunction. Which bacterial component most directly triggered his inflammatory response through TNF-alpha and IL-1 induction?
Answer choices
- APeptidoglycan
- BM protein
- CProtein A
- DLipid A of lipopolysaccharideCorrect answer
- ECapsular polysaccharide
- FTeichoic acids from gram-positive bacterial cell walls
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