PCR-Based Assay for Discrimination between Invasive and Contaminating Staphylococcus epidermidis Strains

Abstract

ABSTRACT The discrimination between Staphylococcus epidermidis strains that contaminate and infect blood cultures is a daily challenge for clinical laboratories. The results of PCR detection of putative virulence genes were compared for contaminating strains, sepsis-related strains, catheter strains, and saprophytic strains. Multiplex PCR was used to explore the atlE gene, which is involved in initial adherence, the intercellular adhesion gene cluster ( ica ), which mediates the formation of the biofilm, and the agrA , sarA , and mecA genes, which might contribute to the pathogenicity of S. epidermidis . Whereas the atlE , agrA , and sarA genes were almost ubiquitously amplified, the ica and mecA genes were detected significantly more in infecting strains than in contaminating strains ( P ≤ 0.02) and thus appeared to be related to the potential virulence of S. epidermidis .