Detection of Enterotoxin Coding Genes of Staphylococcus aureus Strains Isolated From Ground Meat in Retail Shops in Mazandaran

Staphylococcus aureus is one of the most important pathogenic bacteria for human that is easily transferred during slaughtering, processing, packaging, storage and handling of meat and meat products as a result of poor hygienic principles, and causes staphylococcal food poisoning. The objective of this study was to evaluate the contamination of raw and cooked ground beef in retail shops of Mazandaran to S. aureus and also detection of enterotoxin-producing genes in the isolates. One-hundred fifty ground beef samples (95 raw and 65 cooked) were collected randomly from retail shops, 21 May-21 July 2017. S. aureus was counted via culturing on Baird Parker Agar medium. Detection of enterotoxins A-E and G, H, I and J producing genes was conducted applying real-time PCR technique. 68% of samples showed S. aureus contamination. The average count in raw and cooked ground beef samples was 3.1×105 cfu/g and 5.7×103 cfu/g, respectively. From 92 S. aureus isolates, 23 isolates (25%) were carrying enterotoxin coding genes; amongst them 15 isolates (65.2%) were carrying just a single gene and the rest more than one gene. Two isolates carrying SEA+ SEC, two isolates SEA+SEE, one isolate SEA+SEG, one isolate SEC+SEI, one isolate SEA+SEC+SEG and one isolate SEE+SEG. These results show that enterotoxigenic S. aureus strains are present on considerable numbers in retail ground meat in Mazandaran.