Detection of Listeria Monocytogenes in non-Pasteurized Milk in Kerman City by Phenotypic and Molecular Techniques

Listeria monocytogenes is a gram-positive bacterium that causes listeriosis in humans and animals and is present in most foods including dairy and milk. Listeria monocytogenes can cause abortion and mastitis in cattle. In humans, as well as infections in pregnant women, fetuses, and a newborn baby are seen as meningitis septicemia. Despite these microorganisms in milk can be considered as a health indicator. In this study, 50 samples of raw and unpasteurized milk in the city of Kerman were collected and transferred to the laboratory by observing the cold chain. The culture was performed on a Listeria-specific culture medium and phenotypic identification was performed. For molecular identification, the DNA of bacteria identified by the phenotypic method was extracted using a commercial kit. Listeria monocytogenes was detected by using a special IGF kit to identify this bacterium from the Iranian Gene Fanavaran Company. The PCR product was electrophoresed with 1% gel and specific bands were observed. The results showed that 30 and 27 samples of unpasteurized milk showed contamination against Listeria monocytogenes based on the methods performed, culture, and PCR, respectively. This shows the attention and observance of hygienic conditions during the production and preparation of milk and the necessity of using pasteurized milk.