Abstract

Staphylococcus aureus is a major foodborne pathogen that poses significant public health risks through contamination of dairy products and transmission via food handlers. This study aimed to investigate the prevalence of S. aureus in dairy products and food handlers, evaluate antimicrobial resistance patterns, and characterize virulence and resistance genes using molecular techniques. A total of 244 samples were collected, including raw milk (n=48), yogurt (n=47), Kareish cheese (n=49), and human hand swabs from various occupational groups (n=100). S. aureus isolation was performed using standard microbiological methods, followed by coagulase testing and antimicrobial susceptibility testing against 11 antibiotics. Molecular characterization was conducted using PCR amplification of virulence genes (nuc, sea, seb) and resistance gene (mecA). S. aureus was detected in 95/244 (38.9%) samples, with the highest prevalence in raw milk (52.1%), followed by yogurt (42.5%), human hand swabs (35.0%), and Kareish cheese (10.2%). Coagulase-positive S. aureus was found in 35/144 (24.3%) dairy product samples. Among human samples, food handlers showed the highest contamination rate (45.0%), followed by farm workers (47.0%) and veterinarians (10.0%). Antimicrobial resistance analysis revealed high resistance rates to oxacillin (100% in all dairy products), indicating methicillin resistance. Molecular analysis confirmed the presence of the nuc gene in all tested isolates (100%), while enterotoxin genes sea and seb were detected variably. The mecA gene was present in 95% of examined strains, confirming MRSA status. This study demonstrates significant contamination of dairy products with antibiotic-resistant S. aureus, including MRSA strains carrying virulence genes. The high prevalence among food handlers highlights the need for improved hygiene practices and surveillance programs to prevent foodborne infections and limit the spread of antimicrobial resistance.

Key words: Staphylococcus aureus, dairy products, antimicrobial resistance, mecA gene, Zoonoses.