title: 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%). Methicillin resistance was observed in 10% of the S. aureus isolates (n=33). Analysis by PFGE revealed that isolates with the same SCCmec type were unrelated. Instead, biofilm-forming ability tests showed that SCCmec type I MRSA had the highest ability to form a film.
  
  
  CONCLUSIONS
  The strains analyzed in our study showed a homogeneous pattern of SCCmec type. The difference in ability to produce biofilm between strains of SCCmec type I and isolates with other SCCmecs was substantial. This virulence factor could have critical implications for the formation and persistence of chronic SSIs.
authors.affiliation: Department of Cellular and Molecular Biology and Pathology Luigi Califano, University of Naples Federico II, Naples, Italy. giovannapulcrano@libero.it
authors.forename: Giovanna
authors.initials: G
authors.lastname: Pulcrano
authors.forename: Antonio
authors.initials: A
authors.lastname: Vollaro
authors.forename: Fabio
authors.initials: F
authors.lastname: Rossano
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Catania
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms; D016009:Chi-Square Distribution; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D007558:Italy / Q000453:epidemiology; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000502:physiology*; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013530:Surgical Wound Infection / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents