Prevalence of G, H, I, J Enterotoxin Genes and Antibacterial Susceptibility Pattern in Staphylococcus aureus strains Isolated from Different Foods

Background and Staphylococcus aureus is one of the most common causes of foodborne diseases. Enterotoxin produced by the bacterium is one of the very important virulence factors، and pyrogenic toxin super antigens (PTSAgs) that have profound effects on their hosts. This study aimed at evaluating the prevalence of S. aureus strains in different foods، examining their antimicrobial susceptibility patterns and detecting the enterotoxin genes (SEs) and mecA gene in isolated S. aureus strains using PCR. A total of 510 food samples was collected in 2013-2014 in Hamadan، Iran. Food samples were analyzed for S. aureus identification. The antibiotic susceptibility pattern of all isolated bacterium was determined by disk agar diffusion. After extraction of isolated genomic، enterotoxin genes and mecA gene were detected. We isolated 49 (9. 60%) S. aureus strains from 510 food samples. The most frequent resistance was observed to erythromycin and tetracycline in 15 strains (30. 61%)، followed by gentamicin in 14 (28. 57%)، clindamycin in 13 (26. 53%)، ciprofloxacin and rifampin in 12 (24. 48%)، trimethoprim-sulfamethoxazole in 7 (14. 28%)، and cefoxitin in 3 strains (6. 10%). All cefoxitin resistant isolates were positive for mecA gene. Prevalence of SEs were 51. 2% (n=25). Among the genes that code enterotoxins، seg gene were the most frequent that was carried by 36. 73% of the isolates، followed by sei in 12. 24%، and seh in 6. 12% of the isolates. None of the isolates harbored the sej gene. Twenty three isolates carried only one se gene and the remaining two isolates carried two se genes. High prevalence of enterotoxin genes in current study idicates the risk potential of poisoning with foods contaminated by Staphylococcus aureus. The increasing prevalence of enterotoxin and emerging its antibiotic resistance in foods is a serious problem for public health.