Lipid Biochemistry USMLE Step 1 Practice Question
A 72-year-old man with gram-negative sepsis presents with hypotension (BP 78/52 mmHg), tachycardia (HR 118/min), tachypnea (RR 22/min), and fever (38.9°C). Laboratory findings reveal elevated D-dimer (8.2 mg/L) and prolonged PT/INR consistent with disseminated intravascular coagulation. He develops refractory septic shock unresponsive to fluid resuscitation. Platelet count remains above 100,000/μL. The bacterial product most directly triggers macrophage activation through which of the following lipid components?
Answer choices
- AFlagellin hook protein
- BTeichoic acid
- CLipid A of lipopolysaccharideCorrect answer
- DPeptidoglycan tetrapeptide cross links
- EProtein A
- FOuter membrane porin proteins
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.