Investigation of the presence of listeria monocytogenes in chicken meat döners and burgers sold in Istanbul province

Listeria monocytogenes, is one of the 17 species of the Listeria genus, is a Gram-positive rod-shaped bacterium that can grow in wide temperature, pH, and salinity range. It is found in the soil, water, animals, and foods. This bacterium, which has high pathogenicity, is an infection agent called Listeriosis which results in death in humans and animals. The majority of human infections are foodborne. Bacteria are found in milk and cheeses, raw ground beef, red and poultry meats, ready and frozen meals, fruits, and vegetables. In our thesis, chicken meat doner and burgers which were sold in Istanbul providence (cafes, restaurants, and grocery stores) were collected and examined in the laboratory. Gram staining, catalase and oxidase, movement in SIM medium, methyl red and Voges Proskauer, nitrate reduction, sugar fermentation (xylose, rhamnose, ribose, mannitol, and α-methyl-D-mannocyte), CAMP and β hemolysis tests on 5% sheep blood agar were performed of suspected strains of Listeria obtained using ISO 11290-1 method. The iap and hlyA gene regions were examined for the identification of L. monocytogenes of Listeria strains identified by biochemical tests. The serotyping of isolates, identified as L. monocytogenes, was performed by multiplex PCR method and lmo 1118, lmo 0737, orf 2110, orf 2819 and prs gene regions were examined. Antibiotic resistance profiles of strains confirmed by molecular techniques were determined by the Kirby-Bauer disk diffusion method. As a result of the research, L. monocytogenes suspicious bacteria were isolated in 30 of 100 food samples (one from a chicken meat burger sample). It was defined by biochemical tests that 7.8% of 51 isolated bacteria (strains D017, D039, D042, and D044) were Listeria spp. Only 50 % of these strains (D039 and D044) were determined to have iap and hlyA gene regions. When the antibiotic resistance profiles of these two strains identified as L. monocytogenes were examined, both isolates were semi-sensitive to cefaclor; have been found to be sensitive to ampicillin, amikacin, amoxicillin/clavulanic acid, gentamicin, cefaclor, trimethoprim- sulfamethoxazole, tetracycline, chloramphenicol, vancomycin and clarithromycin. One of the isolates, only D044 was found to be semi-sensitive to rifampin. Although both isolates were isolated from doner sample number 30, they were evaluated as separate bacterial strains due to their zone diameters against antibiotics and their resistance to rifampin. When the serotypes of L. monocytogenes isolates were examined by multiplex PCR method, it was confirmed that two isolates belonged to serovar 1/2a, which had prs and lmo 0737 gene regions. By the thesis study, it was determined that chicken meat doners collected from different parts of Istanbul are contaminated with L. monocytogenes, and the incidence of bacteria, although low (2%), poses a threat to human health. It is thought that the reason of contamination is working environments are not sufficient in terms of hygiene, the interior parts are not cooked well during cooking and the circulation at the sales point is high as the cause of contamination