The prevalence and antimicrobial resistance of Listeria spp in raw milk and traditional dairy products delivered in Yazd, central Iran (2016)

Listeria monocytogenes is an important foodborne pathogen which its data in Iranian dairy products is limited. A total of 545 samples of traditional dairy products (raw milk, traditional cheese, traditional butter, traditional curd, and traditional ice cream) were collected from traditional dairy shops located in Yazd, Iran. L. monocytogenes was isolated, and positive samples were confirmed by polymerase chain reaction. Antibiotic sensitivity test was conducted to determine the antibiotic resistance. Listeria species were isolated from 11.7% samples. 4.03% samples were identified as L. monocytogenes, 5.6% as L. innocua, 1.8% as L. seeligeri, and 0.18% L. murrayi. All L. monocytogenes isolates were resistant to tetracycline, chloramphenicol, penicillin, and amoxicillin/clavulanic acid. Consumption of raw milk and its traditional products prepared inadequate heat treatment and the lack of appropriate control measures might lead to serious health problems. As our results show, the Iranian food safety authorities should set up an effective standard to screen all susceptible food for the presence of Listeria spp.