MRSA Skin Abscess: The Daily PANCE Blueprint
A 29-year-old man has had a painful, swollen lump on his thigh for 4 days; he thought it was a spider bite. Several members of his wrestling team have had similar boils this season. He has a 4-cm fluctuant, tender abscess with 4 cm of surrounding redness and warmth, and his temperature is 38.3°C (100.9°F). He has no drug allergies and is otherwise healthy. You perform incision and drainage and send the pus for culture. Which oral antibiotic is the most appropriate to prescribe?
A. Trimethoprim-sulfamethoxazole
B. Cephalexin
C. Amoxicillin
D. Penicillin V
E. Azithromycin
Answer and topic summary
The answer is A. Trimethoprim-sulfamethoxazole
A fluctuant abscess with a “spider bite” story and boils spreading through a contact-sport team is community-acquired MRSA until proven otherwise. Incision and drainage is the most important treatment for any abscess. Antibiotics are added for fever or other signs of systemic illness, extensive surrounding cellulitis, a large or multiple abscesses, immunosuppression, the very young or old, or a hard-to-drain location. His fever alone is enough, and the surrounding cellulitis adds to it. The oral choice must cover MRSA: trimethoprim-sulfamethoxazole, doxycycline, or clindamycin, typically for 5 to 10 days. Cephalexin, amoxicillin, and penicillin cover streptococci (and cephalexin covers methicillin-sensitive staph) but not MRSA; cephalexin is the right pick for nonpurulent cellulitis, which is usually streptococcal. Azithromycin has unreliable staph coverage. Severe infection or systemic toxicity calls for IV vancomycin. Repeated infections or a team outbreak call for hygiene measures (no shared towels, cover wounds, clean mats) and sometimes decolonization with mupirocin and chlorhexidine.
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