Background: Listeria is a gram positive bacterium, facultive intracellular pathogene. Prf A gene has an important role in virulence. The purpose of this study was to determine of the presence of Listeria monocytogenes in various meat products and presence of prf A gene in bacteria isolated from food samples and compare them with clinical samples and standard samples.

Materials and Methods: During 6 months of 60 samples of beef, chicken, ham, cocktail, sausage, from a butchery’s Khoramabad and shops in Khoramabad and Tehran were collected. L. monocytogenes was isolated according to cold enrichment method and prf A gene were analyzed by PCR (polymerase chain reaction) method. Statistical analysis was performed with the software SPSS (statistical package for social science).

Results: From 60 samples of meat and meat products, 8 (13.3%) were positive for Listeria spp. Among in these samples, 4 cases of L. monocytogenes (6.6%), 3 cases (5%), L. innocua and 1 case (1.6%) L. welshimri, were isolated which L. innocua was isolated from meat and poultry samples and L. monocytogens from meat, chicken, ham and L. welshimeri from meat were isolated. Prf A gene was detected in isolated L. monocytogenes and donated bacteria from dairy products, clinical and standard samples, 2 cases of donated samples of vegetable contained prf A genes.

Conclusion: The prf A gene (activator of transcription and regulators the expression of other virulence genes), in the studied samples were observed. This gene plays a role in pathogenesis. Because these bacteria are transmitted through food and is a serious threat to public health. Thus identification of bacteria especially its genes could be possible to find some ways to prevent the bacteria and avoid disease from it.