IDENTIFICATION OF Staphylococcus aureus CHEESE ISOLATES WITH RESPECT TO VIRULENCE PROPERTIES, GENETIC RELATEDNESS AND ANTIBIOTIC RESISTANCE PROFILES

The problems on identification of Staphylococcus aureus isolates from cheese samples were investigated by phenotypic and genotypic tests in this study. Among 207 Staphylococcus spp. isolated from 31 cheese samples, 23 isolates that were Gram positive, catalase and slide coagulase positive, with 1 isolate that was latex agglutination test negative showed different phenotypic properties. Polymerase chain reaction (PCR) and quantitative PCR (qPCR) analyses showed that DNase test and target genes ( nuc , coa ) regarded as gold standard regions for S. aureus were not found to be unique for identification of S. aureus . The toxin genes (SEA-SEE) were not detected by PCR. Antibiotic resistance profiles of S. aureus isolates demonstrated that two isolates were resistant to penicillin G. This study showed that the unique phenotypic and genotypic test was not adequate for identification of S. aureus isolates. There was no correlation between the presence of the nuc gene and toxin genes. The presence of nuc gene which was used for detection of S. aureus was also found to be present in other Staphylococcus isolates. As a conclusion, the results revealed that biochemical tests could lead to false positive results for identification of S. aureus . The presence of nuc gene is not correlated with the presence of toxin genes.