BACKGROUND: Staphylococcus aureus is one of the most important pathogenic microorganisms in meat products, especially those that are repeatedly handled by hand in the production process. Beta-lactam drugs, especially new generations of Cephalosporins, are used for treatment of most infections that are caused by Staphylococcus aureus. But the production of beta-lactamase enzyme by some strains has led to the failure for treating the infections that are associated with this organism. OBJECTIVES: The present study was conducted to evaluate the prevalence and comparison of the antimicrobial effect of methanolic extracts of red pepper and red onion on Staphylococcus aureus with beta-lactamase gene that was isolated from minced meat in Semnan city. METHODS: For this reason, sampling from 30 distribution and supply centers of packaged meat in Semnan city was performed in hygienic conditions and all of the samples were tested for presence of Staphylococcus aureus with beta-lactamase gene by biochemical methods and molecular confirmation by PCR assay. Also, the antibacterial effect of red pepper and red onion extracts on these isolates was evaluated by minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC), well distribution and bacterial growth curve tests. RESULTS: The results showed that 16.6 percent of samples were contaminated with Staphylococcus aureus with beta-lactamase gene. Red pepper and red onion extracts had good antibacterial effects on these isolates and in all the tests, the red pepper extract was more effective than the red onion extract. CONCLUSIONS: By proving stronger antimicrobial effect of red pepper, it is recommended to use pepper in sufficient amounts along with onion in foods that are made from minced meat like all kinds of Kebab.

BACKGROUND: 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. Objectives: 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. Methods: 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. Results: 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. Conclusions: These results show that enterotoxigenic S. aureus strains are present on considerable numbers in retail ground meat in Mazandaran.