Incidence and characterization of Staphylococcus aureus strains isolated from food markets

Staphylococcus aureus is a major foodborne pathogen. The primary purpose of this research was to evaluate S. aureus contamination levels and distribution characteristics in various kinds of food. A total of 121 samples of 11 kinds of food were collected from different food markets in the summer season according to their availability and popularity, and 103 (85.1 %) samples were found to be contaminated with S. aureus. Raw meat, meat products, soybean products, and pickled vegetables are highly contaminated food. For enterotoxin genes analysis, among all the isolates, 20 (19.4 %) possessed sea gene, 2 (1.9 %) with sed gene, 8 (7.8 %) with seg gene, 4 (3.8 %) with seh gene, 24 (23.3 %) with sei gene, 5 (4.8 %) with selj gene, 24 (23.3 %) with selk gene, 44 (42.7 %) with seln gene, and 8 (7.8 %) with ser gene. The seb, sec, see, selm, and selu genes were not found in any of the isolates. For the antibiotic resistance genes tests, most isolates from the food samples were positive for at least 1 of 6 antibiotic resistance genes. The most prevalent resistance genes in samples were ermA (85/103, 82.5 %), followed by tetA (61/103, 59.2 %), chlA (60/103, 58.2 %), norA (56/103, 54.3 %), mecA (10/103, 9.7 %), and blaZ (7/103, 6.8 %). Our results showed that most isolates harbored enterotoxins-producing genes and antibiotic resistance genes, indicating the risk of foodborne S. aureus outbreaks, which drew urgent attention to the great need to improve hygienic conditions in food processing, in order to enhance the safety of food products.