Session: Poster Session: Community-Acquired MRSA
Sunday, October 26, 2008: 12:00 AM
Room: Hall C
Background: The epidemiology of Staphylococcus aureus in the community is poorly understood. We describe S. aureus strains and infection characteristics for community onset infections in Melbourne, Australia. Methods: Patients with community-onset S. aureus infections were identified via clinical specimens submitted to a community-based pathology service. The referring doctor confirmed community-onset and site of infection. Patient isolates were characterised by antibiotic resistance and genetic typing, including presence of Panton-Valentine leukocidin gene (pvl). Results: Between April and September 2006, 2,094 S. aureus isolates were processed. Of these, 11.7% were methicillin resistant (MRSA); 133 (6.4%) multiresistant MRSA (mMRSA) and 110 (5.3%) nonmultiresistant (nmMRSA, resistant to < 3 non-betalactam antibiotics). We followed-up all nmMRSA (34) and mMRSA (15) infections confirmed as community-onset, and a random subset of MSSA (57). The majority were skin infections (99/106) and antibiotics were prescribed for 89% (95%CI: 82, 94). Ten nmMRSA clones were identified, including one pvl positive nmMRSA new to Australia. Of the 29 nmMRSA isolates, 14 were pvl positive (48%; 95%CIs: 30-66%) compared with 16% of MSSA (95%CI: 8-28%), and 0% mMRSA (97.5% CI: 0-23%). Patients with infections with pvl positive strains (23) were on average younger (mean age 23 years (95%CI: 16, 30) compared with the 55 (95%CI: 50, 61)). More pvl positive infections were found in the axilla (17.9% vs 0%) and head and neck (35.7% vs 8.2%), and less in the leg or foot (21.4% vs 55.7%). Conclusions: We report high rates of pvl in both community nmMRSA and MSSA. Infections with pvl positive S. aureus were associated with younger patients and a greater incidence of axillary and head or neck infections.