Burn and trauma units as sources of methicillin-resistant Staphylococcus aureus.

At the time that methicillin-resistant Staphylococcus aureus (MRSA) began to achieve clinical prominence, it was thought to be spread by exogenous vectors. Institution of rigorous infection control efforts, including isolation procedures, was found to have little effect on the frequency of MRSA colonization of burn wounds. It was later found that handwashing was sufficient to prevent cross-contamination. Subsequently, it has been shown that patients can be harboring MRSA at the time of admission to the burn unit and that multiple antimicrobial resistance can develop among organisms that reside in the patient through plasmid-mediated transfer of resistance genes. Excessive use of such agents as the synthetic penicillins and second- and third-generation cephalosporins has selected for the survival of these organisms. Currently, the only available agent for systemic treatment of MRSA infection is vancomycin, the use of which is expensive and associated with significant toxicity. Muciprocin is a topical antimicrobial that promises to be useful in the treatment of such infections. Other agents for systemic use are needed, since use of a single drug to combat MRSA infections seems likely to encourage the emergence of resistant organisms.