samples Antibiotic resistance profile of Salmonella typhimurium isolated from raw milk and traditional cheese

Salmonella is one of the most important bacteria which cause illnesses, may exist in raw foods. The presence of this bacterium in food also causes a decrease in the quality of productions and a decrease in the economic growth. Milk and its products are among the food that may contaminate with Salmonella both primarily and secondarily by employees, water, etc., and transmitted to human. In this study, 100 samples of raw milk and 50 samples of traditional cheese from different parts of Chaharmahal and Bakhtiari province were obtained to isolate and identify Salmonella bacteria using microbiological, and polymerase chain reaction tests. Also, the antibiotic resistance of Salmonella isolates was evaluated by the diffusion disk method. The results of microbiological tests showed that 7 samples were contaminated with salmonella. Suspicious isolates included 5 samples belonging to raw milk and 2 samples belonging to traditional cheeses. The results of PCR test revealed that 3 samples of suspected isolates of raw milk (%3) and 1 sample of suspected isolates of traditional cheese (%2) were S. typhimurium. The results of the antibiogram test on Salmonella isolates showed the highest sensitivity to Gentamicin and Ciprofloxacin, and the highest resistance to Ampicillin, Tetracycline and Trimethoprim sulfamethoxazole antibiotics. According to the results of the present study, raw milk and traditional cheeses are contaminated with Salmonella typhimurium, which are resistant to some antibiotics. Although the contamination of raw milk is removed during the heat treatment steps such as pasteurization, boiling or sterilization, traditional cheeses contaminated with this bacterium are considered a potential risk for the health of consumers. Therefore, the examination of traditional dairy products, especially cheese, in terms of preventing the occurrence of diseases in humans seems to be more necessary.