MRSA has increased in prevalence throughout the world. In addition to being resistant to methicillin, these organisms are also resistant to all β-lactam antibiotics, including cephalosporins. Although they are often thought of as a nosocomial pathogen, MRSA has been increasing in incidence in the community, as well. It is imperative for physicians to recognize MRSA as an important pathogen, and to understand the different characteristics of nosocomial versus community-acquired microbes.

In the United States, there is a high occurrence of MRSA among hospitalized patients. According to the Surveillance and Control of Pathogens of Epidemiologic Importance database, the frequency of MRSA responsible for nosocomial bacteremia increased more than 30% from 1995 to 2001. Significant risk factors for nosocomial MRSA include prolonged hospitalization, prior antibiotic therapy, and proximity to a patient with MRSA. In addition, the incidence of MRSA is pronounced in patients requiring intensive care, with burns, and with surgical wound infections. In children, other documented risk factors for acquisition of nosocomial MRSA are the presence of a central venous catheter or tracheostomy and the undergoing of frequent surgical procedures. The Hospital Infection Control Practices Advisory Committee, the Centers for Disease Control and Prevention, and the Society for Healthcare Epidemiology of America have established guidelines to help prevent the spread of nosocomial MRSA. As the most common route of transmission for nosocomial MRSA is on the hands of health care personnel, these recommendations include good hand hygiene and contact precautions.