Staphylococcus aureus is ubiquitous. It readily grows on human skin and mucous membranes. Methicillin-resistant S. aureus (MRSA) is a strain of S. aureus which by definition is resistant to the semi-synthetic penicillins (i.e. methicillin, nafcillin, and oxacillin). As such, it is resistant to all other beta-lactam antibiotics (including other penicillins, cephalosporins, and cephamycins). Additionally, MRSA is often resistant to other classes of antibiotics including aminoglycosides, macrolides, and quinolones. Thus, MRSA is not only methicillin-resistant but also multiply-resistant as well. MRSA is neither more infectious nor more virulent than methicillin-susceptible S. aureus; however it is much more difficult to treat.

Detection of MRSA within hospitals and long term care facilities has in creased dramatically in the last two decades and a great deal has been written regarding its management and control. The first reports of MRSA isolates occurred in 1961 shortly after methicillin came into clinical use. Since then, MRSA have been a major cause of nosocomial infections in Europe. By the late 1970’s the organism was identified in large teaching institutions in the U.S. Now MRSA is common in all types of hospitals. Once MRSA becomes endemic within a hospital, it is rarely eliminated and may eventually account for 5-50% of all nosocomial Staphylococcal infections. Concern about MRSA is related to the potential for nosocomial transmission and the limited number of antibiotics available to treat infections caused by this organism.