PCR-based assay for discrimination between invasive and contaminating Staphylococcus epidermidis strains

The discrimination between Staphylococcus epidermidis strains that contamin ate and infect blood cultures is a daily challenge for clinical laboratorie s, The results of PCR detection of putative virulence genes were compared f or contaminating strains, sepsis-related strains, catheter strains, and sap rophytic strains. Multiplex PCR was used to explore the atlE gene, which is involved in initial adherence, the intercellular adhesion gene cluster (ic a), which mediates the formation of the biofilm, and the agrA, sarA, and me cA genes, which might contribute to the pathogenicity of S. epidermidis, Wh ereas the atlE, agrA, and sarA genes were almost ubiquitously amplified, th e ica and mecA genes were detected significantly more in infecting strains than in contaminating strains (P less than or equal to 0.02) and thus appea red to be related to the potential virulence of S. epidermidis.