Investigation of mec a gene, virulence traits and antibiotic resistance profiles in methicillin-resistant staphylococcus aureus isolates from dairy products

Abstract

This study was performed to determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in raw milk and dairy products and the presence of virulence traits in the isolates obtained and to assess their resistance to several antibiotics. MRSA was detected by CHROMagar MRSA II in 148 (22.8%) of 650 samples. Ninety-eight isolates were confirmed as MRSA, 86 of these isolates were phenotype-positive, 9 were phenotype/mecA-positive, and 3 were phenotype-negative but mecA-positive. However, the virulence genes were not found in any MRSA strains. According to the results of antibiotic susceptibility tests, 100, 44.9, and 29.6% of strains were resistant to penicillin, tetracycline, and clindamycin, respectively. A low prevalence (1.02%) of resistance was observed against vancomycin and chloramphenicol antibiotics. Furthermore, multidrug resistance was seen among MRSA strains isolated from cheese, butter and buttercream samples. In contrast with other studies, we identified a high-level vancomycin-resistant MRSA strain in one buttercream sample and the intermediate-level vancomycin resistance in six different multiple-resistant MRSA strains from food of dairy origin. Practical applications Recently, MRSA has been isolated from foods of animal origin and become one of the rising public health concerns worldwide. This study focused on the prevalence of MRSA in raw milk and dairy products, the presence of genes encoding virulence factors that allow it to cause the disease and their antibiotic susceptibility patterns. Consequently, we revealed the emergence of resistance to vancomycin and multiple antibiotics among MRSA strains. The isolation of high-level vancomycin-resistant MRSA strain is an important finding because vancomycin continues to be the first-line treatment agent for MRSA infections.