Presence of Staphylococcus aureus in White Cheese: Determination of Enterotoxin and Antimicrobial Resistance Genes

This study aimed to evaluate Staphylococcus aureus contamination, enterotoxin presence, and antibiotic resistance in 100 white cheese samples, both packaged and unpackaged. Polymerase Chain Reaction (PCR) analysis showed S. aureus in 16 (32%) of the 50 unpackaged samples and 8 (16%) of the 50 packaged samples. 46 S. aureus isolates were obtained from 24 S. aureus positive samples. Moreover, the sed gene, associated with enterotoxin production, was detected in two 46 isolates, one from packaged and one from unpackaged white cheese samples. The isolates exhibited resistance to erythromycin (6.52%), gentamicin (10.87%), chloramphenicol (6.52%), trimethoprim-sulfamethoxazole (2.37%), rifampicin (15.21%), tetracycline (28.26%), cefoxitin (43.47%), and penicillin G (34.78%). Oxacillin and vancomycin resistance among the 46 S. aureus isolates was examined using the minimal inhibition concentration (MIC) method. According to the MIC results, none of the isolates were resistant to oxacillin. However, 47.82% of the isolates were resistant to vancomycin. Overall, the isolates exhibited resistance to 9 out of the 10 antibiotics tested. In addition to the resistance profiles, resistance genes were also investigated. It was found that 3 out of the 46 S. aureus isolates (13.6%) carried the mecA gene, 6 (27.2%) carried the mecC gene, and 1 (2.17%) carried both mecA and mecC genes. In conclusion, detecting S. aureus in white cheese indicates poor hygiene. The high antibiotic resistance, presence of resistance genes, and enterotoxin genes in some isolates suggest poses a risk of transmitting resistant microorganisms to humans, potentially complicating disease treatment and causing foodborne illness, posing a public health concern now and in the future.