Bacterial Infections USMLE Step 1 Practice Question
A 27 year old man is brought to the emergency department with fever and pleuritic chest pain for 3 days. He injects heroin daily. Temperature is 39.4 C (102.9 F), blood pressure is 102/60 mm Hg, and oxygen saturation is 91 percent on room air. Cardiac examination reveals a new holosystolic murmur at the left lower sternal border. Chest CT shows multiple bilateral cavitary nodules. Blood cultures grow gram positive cocci in clusters that are catalase positive, coagulase positive, and beta hemolytic. Which of the following virulence factors most directly explains this organism’s ability to evade opsonization and phagocytosis?
Answer choices
- AProtein ACorrect answer
- BPolysaccharide capsule composed of D glutamate
- CM protein
- DCord factor
- EIgA protease
- FLipoteichoic acid
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