Genotype MRSA, a new genetic test for the rapid identification of staphylococci and detection of mecA gene.

Early detection of Staphylococcus methicillin resistance (MR) is essential. However MR determination may be difficult because it is necessary to perform investigation of heterogeneous resistance and low level of resistance and to discriminate between oxacillin resistance and borderline resistance. Several phenotypic methods are recommended but they fail to detect low level of production de PBP2a, the modified Penicillin Binding Protein responsible for MR. Detection of mecA gene, the gene encoding PBP2a, using PCR is considered to be the reference method. We evaluated Genotype MRSA, a new rapid system based on DNA multiplex amplification and further hybridisation, for the identification of staphylococci and detection of the mecA gene. The study was performed on a collection of various Staphylococcus strains (N=30) from clinical human isolates including S. aureus MR and methicillin susceptible (MS), S. epidermidis MR and MS, and other species of coagulase negative Staphylococcus (CNS) MR and MS. For all the strains, the hybridization banding pattern obtained using Genotype MRSA correlated with their expected phenotypic and genotypic characteristics. Genotype MRSA allows the identification of the mecA gene as well as S. aureus and S. epidermidis specific genes. This DNA strip technology based assay can easily be incorporated into routine diagnostics. In addition, the short testing time (less than 2 hours) optimises treatment orientation. Genotype MRSA completely complies with all requirements for a fast, safe, valid and cost-effective MR diagnosis in staphylococci.