Characteristics, control, and treatment of methicillin-resistant Staphylococcus aureus infections

The history, in vitro characteristics, epidemiology, clinical observations, control measures, and therapy of methicillin-resistant Staphylococcus aureus (MRSA) infections are reviewed. Strains of MRSA have been implicated in nosocomial infections, particularly in hospitals associated with medical schools. In vitro, MRSA cultures usually have only a small percentage of organisms that are resistant to methicillin. Patient-specific risk factors for acquiring MRSA infections have been identified in uncontrolled and controlled studies. Environmental culturing to identify sources of contamination has been nonproductive. Physical control measures such as good handwashing and proper isolation have produced variable results in dealing with MRSA. Other suggested measures for reducing the incidence of MRSA colonization include: increasing the nurse-to-patient ratio in intensive-care units; treatment of patients and hospital employees who are colonized with MRSA; and restriction of antibiotics. The drug of choice for treating MRSA infections is vancomycin given intravenously (peripherally or centrally) or by Ommaya reservoir (for CNS infections if bactericidical concentrations are not reached with i.v. doses). Vancomycin may be used empirically for patients at high risk for developing MRSA infections before culture-and-sensitivity reports are available.