[Community-acquired methicillin-resistant Staphylococcus aureus]

Abstract

Recently, methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a cause of community-acquired (CA) infections among patients without established risk factors for MRSA. CA-MRSA strains mainly cause mild skin and soft tissue infections in otherwise healthy children and young adults, but can also cause severe necrotizing fasciitis and pneumonia. In contrast to nosocomial MRSA, CA-MRSA are, in general, susceptible to multiple antimicrobials and present a different genotype. Most CA-MRSA strains share the staphylococcal chromosomal cassette (SCCmec) type IV and produce Panton-Valentine leukocidin (PVL), a cytotoxin that causes leukocyte destruction and tissue necrosis. At present, the predominant clone is the USA300 clone, which is widely disseminated in the United States, Europe and Australia. In Spain, the predominant clone is related to the USA300 clone. The main mechanism of transmission is close person-to-person contact, although household pets and farm animals have also been implicated. In patients with purulent skin and soft tissue infections, the mainstay of treatment is incision and drainage. Antimicrobials are indicated in patients not responding to appropriate drainage. Clindamycin, trimethoprimsulfamethoxazole or tetracyclines can be administered, while the use of fluoroquinolones should be avoided due to the rapid emergence of resistance. For severe infections, vancomycin should be used. Other alternatives are linezolid or daptomycin (only if there is no pulmonary involvement). Adequate hygiene practices are the most efficient measure to prevent spread.