Molecular and phenotypic characterization of methicillin-resistant Staphylococcus aureus from surgical site infections.

Abstract Background: Nosocomial infections represent an important problem for the health of hospitalized patients. Peri-operative infections—those occurring during surgery or in the post-operative period—account for 15%–20% of cases. Most surgical site infections (SSIs) are caused by endogenous gram-positive microorganisms, in particular, Staphylococcus aureus, S. epidermidis, and other coagulase-negative staphylococci that are part of the flora of the skin. Methods: A retrospective study was conducted from January 2006 to December 2010 to describe the epidemiology of methicillin-resistant S. aureus (MRSA) in SSIs. The MRSA isolates were analyzed by a combination of two genotyping methods: SCCmec and pulsed-field gel electrophoresis (PFGE). Also, biofilm-forming ability was analyzed for all isolates as an indicator of their ability to persist despite antibiotic treatment. Results: During the study period, 1,793 swabs from SSIs were analyzed, and S. aureus was identified in 318/987 positive specimens (32%)...