Detection of Listeria Monocytogenes in Dressed Broiler Chicken and Ready-to-Eat Meat Products in Khartoum State - Sudan

Abstract

The aim of this study was to detect and identify Listeria monocytogenes from raw dressed broiler chicken, frozen, shock frozen dressed broiler chicken, ready-to-eat (RET) meat products, frozen and shock frozen raw dressed broiler chicken and from breeding and slaughter houses for broiler chicken in Khartoum State - Sudan, using conventional methods (ISO 11290-1, 2004) and biochemical methods, and further confirmation by using Microbact™ Listeria 12L Kit System (Oxoid, MB1128A) and polymerase chain reaction technique (PCR). The samples subjected to the isolation and identification of Listeria monocytogenes included the following: a total of five hundred (500) samples, of fresh raw dressed broiler chicken, and five hundred (500) samples, of frozen raw dressed broiler chicken, two hundred fifty (250) samples, ready-to-eat (RET) meat (frozen chicken-burger, chicken-sausage , frozen chicken meat balls (kofta), chicken-shawerma, and mortadella) , three hundred (300) samples (100 fresh raw dressed broiler chicken,100 frozen raw dressed broiler chicken and 100 shocked frozen raw dressed broiler chicken) and one hundred (100) swabs from breeding and slaughter houses for broiler chicken in Khartoum state – Sudan. Also two hundred forty (240) samples raw dressed broiler chicken artificially infected with listeria monocytogenes in the laboratory were divided into two groups, in one group 120 samples were exposed to shock - freezing at ( – 40° C) for six hour then kept at (– 18º C) ,in the other group 120 samples were kept at (– 18º C). Each month ten samples from each part were used to detect the presence of listeria monocytogenes. in frozen and shock - frozen artificially infected chicken meat. The isolate (97) of listeria monocytogenes were subjected to antibiotics sensitivity by using Microbroth Dilution Method. xxii From five hundreds (500) samples of fresh raw dressed broiler chicken 204 samples (40.8%) yielded listeria spp. these were distributed as follows: L. monocytogenes 68 samples (13.6%),Listeria ivanovii 99 samples (19.8%),Listeria grayi 23 samples (4.6%),Listeria seeligeri 5 samples (1%) and Listeria welshimeri 10 samples (2%). From five hundreds (500) samples of frozen raw dressed broiler chicken 195 samples (39%) yielded listeria spp. these were distributed as follows: L. monocytogenes 64 samples (12.8%),Listeria ivanovii 97 samples (19.4%),Listeria grayi 20 samples (4%),Listeria seeligeri 5 samples (1%) and Listeria welshimeri 9 samples (1.8%). From two hundred fifty (250) samples of ready-to-eat (RET) meat. (frozen chicken-burger, chicken-sausage , frozen chicken meat balls (kofta), chicken-shawerma, and mortadella) 95 samples (38%) yielded listeria spp. these were distributed as follows: L. monocytogenes 34 samples (13.6%),Listeria ivanovii 52 samples (20.8%),Listeria grayi 4 samples (1.6%),Listeria seeligeri 2 samples (0.8%) and Listeria welshimeri 3 samples (1.2%). From three hundred (300) samples, of ( 100 fresh raw dressed broiler chicken,100 frozen raw dressed broiler chicken and 100 shocked frozen raw dressed broiler chicken) 111 samples (37%) yielded listeria spp. these were distributed as follows: L. monocytogenes 39 samples (13 %),Listeria ivanovii 54 samples (18%),Listeria grayi 11 samples (3.6%), Listeria seeligeri 5 samples (1%) and Listeria welshimeri 4 samples (1.3%). From one hundred (100) swabbing samples from Breeding and Slaughter house broiler chicken 41 samples (41%) yielded listeria spp. these were distributed as follows: L. monocytogenes 12 samples (12%), Listeria ivanovii 23 samples (23%), Listeria seeligeri 5 samples (5%) and Listeria welshimeri 11 samples (11%).listeria monocytogenes was isolated mainly from hand workers and water in both breeding house and slaughter house. Listeria monocytogens survived freezing (- 18º C) and shock - freezing (- 40º C) for twelve month in all samples examined (240). xxiii As a conclusion the conventional method showed that out of total 1650 samples, 646 (39.15%) were found to be contaminated with Listeria spp. 217 (13.15%) were found to be contaminated with Listeria monocytogens, 68 (13.6%) samples fresh raw dressed broiler chicken, 64 (12.8%) frozen raw dressed broiler chicken, 34 (13.6%) samples ready-to-eat (RET) meat, 39 (13%) samples frozen and shocked frozen raw dressed broiler chicken and 12 (12%) samples from breeding – slaughter house broiler chicken. On the bases of the act A gene (827bp), hyl A gene (417bp) and iap gene (131bp), PCR method identified only 97 out of 217 as Listeria monocytogenes. Listeria monocytogenes strains isolated from raw dressed broiler chicken, Frozen, shock frozen dressed broiler chicken and read to eat (RTE) meat products and breeding – slaughter house broiler chicken were susceptible to ampicillin, Chloramphenicol, Doxycycline, Imipenem, Teicoplanin, Rifampicin, Trimethoprim and Vancomycin and resistant to Fosfomycin. The results presented in this study indicate the potential risk of contamination of raw dressed broiler chicken, frozen dressed broiler chicken, ready-to-eat (RTE) meat chicken products by Listeria monocytogenes.