COMPARISON OF VARIOUS METHODS AND REAGENTS FOR SPECIES IDENTIFICATIONOF STAPHYLOCOCCUS-AUREUS POSITIVE OR NEGATIVE FOR THE MECA GENE

The reliability of various methods for species identification of Staph ylococcus aureus was evaluated. A total of 135 coagulase-positive (SA) or -negative (SS) staphylococcal isolates were tested, including meth icillin-resistant (MR) and -susceptible (MS) strains. When the nuc gen e which encodes the S. aureus thermonuclease (TNase) was amplified in a multiplex PCR simultaneously with the mecA gene which encodes for th e MR-associated penicillin-binding protein 2a of staphylococci, the nu c amplification showed full agreement with the results of the coagulas e test. TNase detected by an enzymatic method or as protein in a sandw ich ELISA identified S. aureus with nearly the same precision as the P CR. The Staphylase, Monostaph and Staphaurex agglutination kits were a ll reliable for identification of MSSA, but not for MRSA. Most of the negative MRSA strains were identified by the Pastorex agglutination ki t, in which reagents for fibrinogen receptor and protein A detection h ave been supplemented with antibodies for capsular polysaccharides of the serotypes 5 and 8. These results show that detection of the nuc ge ne or its TNase product is highly reliable for identification of both MRSA and MSSA strains, while various widely used agglutination kits do not show the same reliability for identification of MRSA strains.