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Pathogenic Bacteria

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A 14-year-old boy presented with a 3-day history of vomiting, diarrhea, sore throat, headache, weakness, and fever. His temperature was 39.9°C. He had pharyngeal inflammation, and his blood pressure was 60/0 mm Hg while supine and unobtainable when sitting. Initial laboratory findings included white blood cell (WBC) count of 13 600l/mL with a pronounced left shift (ie, many immature forms), blood urea nitrogen (BUN) of 24 mg/dL (normal up to 15 mg/dL), and abnormal urinalysis, with 20 to 30 WBCs and 8 to 10 red blood cells (RBC) per high-power field.

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He was treated with large volumes of intravenous fluids and with penicillin; his blood pressure rose, but he had multiple episodes of disorientation, and diffuse erythroderma developed. On admission, a small crusted wound had been noticed on the dorsum of his left foot (the result of a bicycle injury 1 week earlier); 45 hours later the wound became red, warm, and pustular, and a left femoral lymph node became tender and enlarged. A culture of the pustule grew S aureus coagulase-positive resistant to penicillin. Several cultures of blood and a throat swab taken before antibiotic therapy was started had been negative. He improved with cephalexin therapy. He had extensive desquamation of the skin of the palms and soles 2 weeks after discharge.

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Which one of the following is most responsible for the nature of the lesion on this boy's foot?

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A. Coagulase

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B. Catalase

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C. Superantigen toxin (StaphSAg)

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D. Exfoliatin

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E. α-Toxin

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A 14-year-old boy presented with a 3-day history of vomiting, diarrhea, sore throat, headache, weakness, and fever. His temperature was 39.9°C. He had pharyngeal inflammation, and his blood pressure was 60/0 mm Hg while supine and unobtainable when sitting. Initial laboratory findings included white blood cell (WBC) count of 13 600l/mL with a pronounced left shift (ie, many immature forms), blood urea nitrogen (BUN) of 24 mg/dL (normal up to 15 mg/dL), and abnormal urinalysis, with 20 to 30 WBCs and 8 to 10 red blood cells (RBC) per high-power field.

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He was treated with large volumes of intravenous fluids and with penicillin; his blood pressure rose, but he had multiple episodes of disorientation, and diffuse erythroderma developed. On admission, a small crusted wound had been noticed on the dorsum of his left foot (the result of a bicycle injury 1 week earlier); 45 hours later the wound became red, warm, and pustular, and a left femoral lymph node became tender and enlarged. A culture of the pustule grew S aureus coagulase-positive resistant to penicillin. Several cultures of blood and a throat swab taken before antibiotic therapy was started had been ...

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