Antibiotic resistance of Staphylococcus aureus isolated from raw beef sold in meat processing plants and markets

Staphylococcus aureus (S. aureus) is a pathogenic bacterium capable of colonizing human and animal hosts while persisting on environmental surfaces. Due to its ability to spread via direct and indirect transmission, it poses a major risk for food contamination, necessitating stringent hygiene control throughout food storage, processing, and distribution.

This study aimed to detect the S. aureus contamination in raw beef and surface swabs from meat markets and assess antibiotic resistance. A total of 372 samples were analyzed: 160 from a meat processing plant and 212 from meat markets. S. aureus was identified using polymerase chain reaction (PCR) targeting the nucA gene, following the ISO 6888-1:2021 standards. Antibiotic susceptibility was assessed using the Kirby–Bauer disk diffusion method, with the results interpreted according to the CLSI M100-S27 guidelines. Resistance genes (mecA, mecC, vanA, and vanB) were detected using PCR.

No S. aureus was detected in the meat processing plant samples. However, 31.3% of the raw beef and 17.3% of the surface swabs from markets tested positive. The isolates from the raw beef exhibited the highest resistance to oxacillin, ampicillin, and penicillin. Over 50% of the surface swab isolates demonstrated resistance to oxacillin, tetracycline, azithromycin, and clindamycin. The mecA gene was found in 24.4% of the raw meat isolates and 35.7% of the surface swab isolates, whereas vanA, vanB, and mecC were not detected.

The high prevalence of S. aureus contamination and antibiotic resistance in meat markets presents potential public health risks. These findings emphasize the need for improved food safety measures, strict hygiene regulations, and responsible antibiotic use. Continuous surveillance and novel therapeutic strategies are essential for mitigating the risks associated with antibiotic-resistant bacteria.