Comparison of Community- and Health Care–Associated Methicillin-Resistant <EMPH TYPE="ITAL">Staphylococcus aureus</EMPH> Infection

To characterize epidemiological and microbiological characteristics of community-associated MRSA cases compared with health care-associated MRSA cases. DESIGN, SETTING, AND PATIENTS: Prospective cohort study of patients with MRSA infection identified at 12 Minnesota laboratory facilities from January 1 through December 31, 2000, comparing community-associated (median age, 23 years) with health care-associated (median age, 68 years) MRSA cases. MAIN OUTCOME MEASURES: Clinical infections associated with either community-associated or health care-associated MRSA, microbiological characteristics of the MRSA isolates including susceptibility testing, pulsed-field gel electrophoresis, and staphylococcal exotoxin gene testing.

Of 1100 MRSA infections, 131 (12%) were community-associated and 937 (85%) were health care-associated; 32 (3%) could not be classified due to lack of information. Skin and soft tissue infections were more common among community-associated cases (75%) than among health care-associated cases (37%) (odds ratio [OR], 4.25; 95% confidence interval [CI], 2.97-5.90). Although community-associated MRSA isolates were more likely to be susceptible to 4 antimicrobial classes (adjusted OR, 2.44; 95% CI, 1.35-3.86), most community-associated infections were initially treated with antimicrobials to which the isolate was nonsusceptible. Community-associated isolates were also more likely to belong to 1 of 2 pulsed-field gel electrophoresis clonal groups in both univariate and multivariate analysis. Community-associated isolates typically possessed different exotoxin gene profiles (eg, Panton Valentine leukocidin genes) compared with health care-associated isolates.