Prevalence, risk factors, and molecular epidemiology of methicillin-resistant Staphylococcus aureus among newly arrested men in Baltimore, Maryland

Abstract

Outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) within prison populations seemingly attest to its spread within the corrections industry; however, the extent of MRSA colonization on arrest is unknown. This study determined the prevalence and risk factors of S aureus on arrest. Nasal swabs from 602 newly arrested men were evaluated. Risk factors were assessed through self-report. Molecular characterization of each isolate was completed. The prevalence of S aureus nasal colonization was 40.4% (243/602). MRSA colonization was found in 15.8% (95/602) of the total population and in 39.1% (95/243) of the total S aureus isolates. Twenty-three skin infections were identified; of these, 11 (47.8%) were S aureus infections, with methicillin-susceptible S aureus (MSSA) in accounting for 3 cases (13.1%) and MRSA accounting for 8 cases (34.8%). In 2 cases (25%) of MRSA wound infection, the nasal colonizing strain was MSSA. By pulsed-field gel electrophoresis, 76 of 95 (80%) nasal isolates were found to be USA300 or related subtypes, with the other 19 (20%) being non-USA300 strains. The Panton-Valentine leukocidin gene was identified in 38 (97.4%) USA300 isolates and in 6 (31.6%) non-USA 300 isolates. MRSA colonization is far greater in this sample than in the general public. USA300 subtypes are highly prevalent. History of previous arrest was not associated with increased MRSA prevalence. MRSA risk factors differed significantly between those with and without a history of previous arrest.