MRSA Update

Staphylococcus aureus (S. aureus) is a gram positive bacterium that causes a variety of diseases. These include skin and soft tissue infections, endocarditis, blood stream infections, pneumonia, and deep-seated abscesses. Staphylococcus aureus also causes osteomyelitis, surgical wound infections, toxic shock syndrome, and food poisoning. 1,2 It has become the most frequent cause of these infections seen in emergency room departments across the United States.3 Methicillin-resistant Staphylococcus aureus (MRSA) has emerged over the past 50 years as an important pathogen, particularly in the health care setting, and the prevalence of this disease-causing bacteria is increasing. Methicillin is a penicillinase-resistant semi-synthetic penicillin that was introduced in 1959. By 1961 methicillin-resistant strains were first described in England. While initially a hospital-based pathogen, MRSA has evolved through numerous major lineage changes to now include a community-based component.4,5 The first community-acquired outbreak of MRSA (CAMRSA) occurred in 1982; documented in an intravenous drug user in Detroit, Michigan.6 Since then, CAMRSA has reached epidemic proportions.7,8,9 MRSA/CAMRSA is important to recognize early, as it is a virulent pathogen that often produces rapidly progressive disease and is often resistant to other commonly used antibiotics. Epidemiology of CAMRSA infections has indicated that certain predisposing factors do exist. These include dialysis, immunosuppression, foley catheter or nasogastric tube placement, intravenous drug use, chronic disease, diabetes, and parental nutrition, all of which predispose to more severe cases of MRSA. The predisposing factors for less severe cases of CAMRSA include environmental exposure at day care centers, prisons, or long term care facilities; recent hospitalization; internal medical device usage; prolonged antibiotic therapy