Abstract
The current study was conducted to determine the occurrence of Listeria species in live chicken and some chicken products (fillets, burger and luncheon). In addition, determine the antibiogram profile of Listeria strains and detection of some virulence genes of Listeria monocytogenes which recovered from the examined samples. The study included 100 samples including cloacal swabs from broiler chicken (n =25) from 5 different broiler chicken farms beside as well as chicken products (25 samples each of chicken fillets, burger and luncheon) that were randomly purchased from supermarkets. Isolation and identification of Listeria was performed according to the standard protocol provided by ISO (2017) using Listeria selective agar (Oxford formulation) with Listeria selective supplement then the suspected colonies were identified using a panel of biochemical tests. It was recorded that the recovery rate of Listeria species from the examined samples was 24, 20, 8 and 16%, in cloacal swabs, chicken fillets, burger and luncheon, respectively with an overall incidence of 17%. In addition, biochemical identification of the recovered Listeria isolates revealed the presence of L. monocytogenes, L. innocua, L. ivanovii, L. seeligeri and L. grayi with various rates where L. monocytogenes scored the highest rate 29.4% (5 isolates). Antimicrobial susceptibility of Listeria strains (n=17) clarified that the highest antibiotic resistance was recorded when using streptomycin (82.4%) followed by Neomycin (76.5%) then Doxycycline and Cefotaxime (52.9%) while the lowest resistance was noticed when using Amikacin (11.8%) then Ciprofloxacin (35.3%). Finally, molecular detection of virulence genes in the identified L. monocytogenes strains (n= 5) clarified the detection of iap and actA genes in the five isolates while hylA gene was detected in three isolates only. At the end, results obtained by this study emphasize a significant occurrence of resistant Listeria in chicken and chicken products including processed animal-originated foods commonly purchased by the public in including; chicken fillets, burger and luncheon. Seriously, the presence of such resistant bacteria endangers human health by making routine antibiotic courses useless in the treatment of such infections. Finally, data proved that retail foods of animal origin pose a risk to human health.

Key words: Listeria, Chicken, Products, Virulence factors, Antibiotic susceptibility