Genetic study of methicillin-resistant, coagulase-negative staphylococci

Abstract

In order to study the genetics of methicillin-resistant, coagulase-negative staphylococci (MRCNS), we examined and identified 17 MRCNS strains by DNA-DNA hybridization and by analysis of plasmid and chromosomal DNA. We detected the mec A gene in 16 of the 17 strains. DNA-DNA hybridization identified 60% of the MRCNS strains tested as Staphylococcus epidermidis. All but one strain possessed some plasmid DNA, and each plasmid profile was different. Chromosomal DNA analysis by pulsed-field gel electrophoresis (PFGE) indicated that all of the strains could be classified as one of 13 PFGE patterns. These results indicate that most of the MRCNS strains isolated from MRSA screening agar were mec A gene-positive, and possessed various plasmid DNA and genotypical chromosomal DNA.