• Nimalie D Stone, Donna R Lewis, Theodore M Johnson, Thomas Hartney, Doris Chandler, Johnita Byrd-Sellers, John E McGowan, Fred C Tenover, John A Jernigan, Robert P Gaynes, and Southeast Veterans Affairs Long-Term Care Methicillin-Resistant Staphylococcus aureus Cooperative.
• Emory University School of Medicine, Atlanta, Georgia, USA. nstone@cdc.gov
• Infect Control Hosp Epidemiol. 2012 Jun 1; 33 (6): 551-7.

ObjectiveTo identify risk factors associated with methicillin-resistant Staphylococcus aureus (MRSA) acquisition in long-term care facility (LTCF) residents.DesignMulticenter, prospective cohort followed over 6 months.SettingThree Veterans Affairs (VA) LTCFs.ParticipantsAll current and new residents except those with short stay (<2 weeks).MethodsMRSA carriage was assessed by serial nares cultures and classified into 3 groups: persistent (all cultures positive), intermittent (at least 1 but not all cultures positive), and noncarrier (no cultures positive). MRSA acquisition was defined by an initial negative culture followed by more than 2 positive cultures with no subsequent negative cultures. Epidemiologic data were collected to identify risk factors, and MRSA isolates were typed by pulsed-field gel electrophoresis (PFGE).ResultsAmong 412 residents at 3 LTCFs, overall MRSA prevalence was 58%, with similar distributions of carriage at all 3 facilities: 20% persistent, 39% intermittent, 41% noncarriers. Of 254 residents with an initial negative swab, 25 (10%) acquired MRSA over the 6 months; rates were similar at all 3 LTCFs, with no clusters evident. Multivariable analysis demonstrated that receipt of systemic antimicrobials during the study was the only significant risk factor for MRSA acquisition (odds ratio, 7.8 [95% confidence interval, 2.1-28.6]; P = .002). MRSA strains from acquisitions were related by PFGE to those from a roommate in 9/25 (36%) cases; 6 of these 9 roommate sources were persistent carriers.ConclusionsMRSA colonization prevalence was high at 3 separate VA LTCFs. MRSA acquisition was strongly associated with antimicrobial exposure. Roommate sources were often persistent carriers, but transmission from roommates accounted for only approximately one-third of MRSA acquisitions.

31 keywords...

hide…