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USA300 methicillin-resistant S. aureus (USA300 MRSA) colonization and the risk of MRSA infection in residents of extended-care facilities

  • S. M. SHURLAND (a1), O. C. STINE (a1), R. A. VENEZIA (a2), M. ZHAN (a1), J. P. FURUNO (a1), R. R. MILLER (a1) and M.-C. ROGHMANN (a1) (a3)...

To examine the pathogenesis of USA300 MRSA infection in long-term care residents, we performed a retrospective cohort study of 1691 adult residents of two extended-care facilities from 2003 to 2007 to assess whether the risk of subsequent MRSA infection is higher in USA300 MRSA-colonized residents compared to non-colonized residents or non-USA300 MRSA colonized residents. Six per cent of residents were colonized with USA300 MRSA; 12% of residents were colonized with non-USA300 MRSA; and 101 residents developed MRSA infection. The risk of infection was twofold higher in residents colonized with USA300 MRSA compared to residents not colonized with MRSA [adjusted hazard ratio 2·3, 95% confidence interval (CI) 1·1–4·5]. The risk of infection in USA300 MRSA-colonized residents was similar to USA300 MRSA non-colonized residents (relative risk 1·1, 95% CI 0·5–2·3). Our findings show that colonization with USA300 MRSA increases the risk of MRSA infection suggesting a similar pathogenesis.

Corresponding author
*Author for correspondence: M.-C. Roghmann, M.D, M.S., 685 W. Baltimore St., MSTF 3-36, Baltimore, MD 21201, USA. (Email:
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Epidemiology & Infection
  • ISSN: 0950-2688
  • EISSN: 1469-4409
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