Evaluation of contamination of dairy products with Listeria monocytogenes and determination of their antibiotic resistance

BACKGROUND AND OBJECTIVESListeria monocytogenes is a type of pathogenic bacteria that causes listeriosis infection. One of the most significant infections related to milk and milk products. Listeria monocytogenes is the major species that causes listeriosis in people and animals which can spread by contaminated food.METHOD AND MATERIALSFor this purpose, ۱۰۰ samples of raw milk (۷۰ samples), local butter (۱۳ samples) and cheese (۱۷ samples) were selected and collected to identify samples suspected of Listeria monocytogenes. The desired samples were taken to the laboratory for diagnosis by observing the temperature cycle. The approved samples were selected to evaluate the antimicrobial sensitivity of Listeria monocytogenes isolates by disc diffusion method and using ampicillin, gentamicin, erythromycin, chloramphenicol, tetracycline, ciprofloxacin antibiotics.RESULTS AND DISCUSSIONOf the total samples of Listeria monocytogenes isolated from dairy products, ۳۵% of raw milk products, ۱۵% of local butter samples, and ۲۴% of cheese samples were infected with Listeria monocytogenes. The results of the antibiotic resistance of dairy samples showed that the resistance to ampicillin was ۶۶.۴% and tetracycline was ۵۴.۳%. The highest level of Listeria resistance in butter samples was to erythromycin (۶۹.۶%) and in cheese samples to ampicillin (۷۱.۲%). The average results obtained in the antibiogram test in samples resistant to Listeria monocytogenes were analyzed with ۹۵% confidence and one-way analysis of variance.CONCLUSIONBased on the results of this study, the risk of contamination of raw dairy products with Listeria monocytogenes is increasing and this contamination is more in samples of raw milk and local butter than in other products.

کلیدواژه ها:

Listeria monocytogenes ، raw Milk ، dairy products ، cheese ، butter samples