PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF LISTERIA SPECIES ISOLATED FROM CHICKEN AND MILK PRODUCTS

L.monocytogenes is wide spread in the environment and can be isolated from a wide variety of food. As such it can be expected to be present in ready-to-eat foods that contain raw ingredients. The risk caused by L. monocytogenes is dependent on the food and how long it is stored. To estimate the incidence and levels of Listeria spp. in different food sources, A total of 200 random samples which collected from different sources 65 samples isolated from poultry , 45 from poultry byproducts (Frozen chicken meat balls (kofta), Frozen chicken burger and frozen chicken sausages), 20 from pasteurized milk ,30 from milk products (Feta cheese ,cream cheese )and 40 from poultry eggs .Only 7(14%) of samples that collected from suspected isolates and detected on Oxford agar, PALCAM agar and ALOA agar were suspected to be Listeria spp. The in-vitro antimicrobial sensitivity test showed that the isolated L.monocytogenes were sensitive to Sulphamethoxazole /trimethoprim, Gentamycin ,Ceftazidime and Cephazoline followed by Sulphamethoxazole, ceftriaxone , weak sensitivity to Penicillin , While they were resistant to Erythromycin, Clindamycin, Ampicillin. All L.monocytogenes were virulent strains as all of them were positive to CAMP test; showed narrow zone of β?hemolysis on sheep blood agar .The PCR results for Listeria isolates showed that all strains are L.monocytogenes and detect 16SrRNA gene and have mefA ,tet M and ampC genes (100%) as resistance genes while Cat and Aad6 genes detected as 85.7% and 71.4% respectively.