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Updated June 18, 2013

Case 6: Methicillin-Resistant Staphylococcus aureus (MRSA) Skin and Soft Tissue Infections

Author: David H. Spach, MD

A 26-year-old HIV-infected man with a CD4 count of 429 cells/mm3 presents with a 5-day history of a skin lesion on his left hand. He describes having a pimple-like lesion on the dorsal surface of his left hand that has now progressed with erythema surrounding the initial lesion. In addition, the lesion has gradually expanded and has become tender (Figure 1). A diagnosis of methicillin-resistant Staphylococcus aureus (MRSA) is suspected.

Which of the following statements is TRUE regarding community-acquired skin and soft tissue MRSA infections in HIV-infected persons?

A Resistance to methicillin and cephalexin results from production of an altered penicillin-binding protein by S. aureus that has reduced affinity for binding to beta-lactam antibiotics.
B More than 30% of the isolates from skin and soft tissue infections have shown resistance to trimethoprim-sulfamethoxazole (Bactrim, Septra).
C Ciprofloxacin (Cipro) is one of the preferred oral regimens.
D In a patient allergic to trimethoprim-sulfamethoxazole, azithromycin (Zithromax) is considered the preferred alternative.
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    Figure 1. Soft Tissue Infection of the Left Hand of HIV-Infected Patient
    Figure 1