Predominance of Methicillin-Resistant Staphylococcus aureus among Pathogens Causing Skin and Soft Tissue Infections in a Large Urban Jail: Risk Factors and Recurrence Rates

Abstract

In the 1990s, community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains emerged as pathogens outside of the health care environment. Epidemic foci of CA-MRSA infections were reported in jails and prisons, but risk factors for MRSA infection there are not known. All skin and soft tissue infections (SSTIs) cultured in the Cook County Jail in March 2004 to August 2005 were reviewed. Demographic and clinical risk factors were compared among patients with methicillin-susceptible S. aureus (MSSA) SSTIs and those with MRSA SSTIs. Antibiotic susceptibilities were recorded, and we performed multilocus sequence typing on a sample of MRSA isolates. There were 378 SSTIs from different patients requiring culture, of which 240 (63.5%) were of MRSA and 43 (11.4%) were of MSSA; 84.8% of S. aureus isolates were MRSA. MRSA- and MSSA-infected patients were similar with regard to age, gender, ethnicity, previous exposure to the jail, and comorbidities. In the 12 months prior to the index culture, MRSA patients were more likely to have received a beta-lactam antibiotic (25% versus 9%; P = 0.02). Among 26 MRSA strains, 24 (92%) had the sequence type 8 (ST8) genotype. Within 6 months, 14% (95% confidence interval, 8.7% to 22.3%) of MRSA SSTI patients in the jail had a recurrent SSTI compared with 8.8% (95% confidence interval, 2.1% to 32.6%) of MSSA SSTI patients (P = 0.004). MRSA is the predominant cause of SSTIs requiring culture in the jail. Few risk factors differentiated MRSA from MSSA SSTIs, and detainee patients with MRSA SSTIs are at high risk for recurrent SSTIs.