Community-acquired MRSA: Major cause of skin, soft-tissue infection

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common identifiable cause of skin and soft-tissue infections, according to a prospective study of patients at least 18 years old who visited an emergency department seeking care for such an infection.

A total of 422 patients with a skin or soft-tissue infection-mostly abscesses but also wounds and cellulitis with purulent exudate-were enrolled in the prospective study, conducted in 11 geographically diverse metropolitan areas in the United States. S aureus was isolated from the site of infection in approximately three quarters of the patients; of those isolates, 78% were MRSA.

Other organisms isolated from at least 1% of isolates included methicillin-susceptible S aureus in 17% and Streptococcus spp in 7%. Cultures from 31 patients were polymicrobial; 10 of those patients had an MRSA infection.

Potential risk factors for infection with MRSA-compared to what was found with other bacteria-included antibiotic use in the month before study enrollment, abscess or lesion attributable to a spider bite, history of MRSA infection, and a recent history of close contact with someone who had a similar skin infection (Moran GJ et al: N Engl J Med 2006;355:666).

Commentary The news here is not that community-acquired MRSA exists-you know that. What is new is just how common this micro-organism has become. Community-acquired MRSA was the most common cause of skin abscess and purulent cellulitis in 10 of 11 participating EDs from across the country.

This information should change how you evaluate, treat, and follow patients who have a skin infection: Culture often, choose an antibiotic appropriately, and encourage early follow-up for failure to improve.