Molecular Identification of Listeria monocytogenes in Raw Hamburgers from Kerman, South-East of Iran

Background: Listeria monocytogenes is a Gram-positive and facultative anaerobic foodborne bacterium which is capable of intra and extra cellular growth. L. monocytogenes usually can exist on different surfaces and instruments at production and processing sites of food products with animal origin. In Iran, the consumption of burger has increased recently, but its safety is still of great concern. Despite few reports from some areas of Iran, there is limited information about burger contamination in Kerman province. Therefore, this research was set to molecular identification of L. monocytogenes in hamburgers distributed in Kerman, Iran. Methods: A total of 100 raw hamburgers were collected from 20 fast food/sandwich shops in Kerman city, Iran during summer 2014. The hamburgers stored in ice box and transported to the food hygiene laboratory. The samples were microbiologically analyzed for the presence of L. monocytogenes. The isolated bacteria were confirmed by molecular assay. Results: Three out of 100 (3%) hamburger samples were biochemically diagnosed as Listeria contamination; however molecular identification assay confirmed that two of them were L. monocytogenes. Conclusion: Although the prevalence rate of L. monocytogenes was not high in hamburger samples of Kerman, the risk of human listeriosis must not be ignored or underestimated. Further surveys are required in future for risk assessment of this pathogenic bacterium in other food products distributed in the country.