MOLECULAR IDENTIFICATION OF PLASMID MEDIATED ANTIMICROBIAL RESISTANCE DETERMINANTS AMONG SALMONELLA ENTERICA IN ILL-CHICKEN

Gamal A Younis, Rasha M Elkenany and Samar A Asfor

Page No: 1-12

Salmonella enterica is a prominent cause of salmonellosis throughout the world. In this study, 17 (9.4%) out of 180 samples from ill-chicken were positive for Salmonella enterica. S. Typhimurium and S. Kentucky were the most common serotypes 4 (23.52% each), followed by S. Enteritidis (3, 17.6%), S. Labadi (2, 11.8%), S. Larochelle, S. Tamale, S. Takoradi and S. Papuana (1, 5.9% each). Concerning the occurrence of Salmonella enterica in ill-chicken viscera, it was clear that liver (41.2%) was the most site of isolation followed by yolk sac (23.5%) then, spleen and heart (17.6% each). Overall, the antimicrobial resistance testing showed higher resistance rates to tetracycline (94.11%), penicillin (94.11%), erythromycin (94.11%), doxycycline (88.23%), streptomycin (88.23%) and nalidixic acid (82.35%). On the contrary, lower rates of resistance were observed for ceftriaxone, ciprofloxacin, cephalothin (5.88%, each), norfloxacin, amoxicillin-clavulonic acid (11.76%), cefotaxime (17.64%) and gentamicin (23.52%). A number of antimicrobial resistance genes including [blaTEM, blaCTX, tetA(A) and ere(A)] in the most common Salmonella enterica serovars (S. Typhimurium, S. Enteritidis and S. Kentucky) were determined on plasmids and chromosomal DNA of five isolates using PCR. The blaTEM genes, that responsible for the extended spectrum -lactamase phenotype, were present on plasmids and bacterial chromosome of all examined isolates of S. enterica. Moreover, one isolate harboring the blaTEM gene also contained blaCTX on plasmid only. Also, tet(A) and ere(A) genes were identified in all tested Salmonella isolates on plasmids and bacterial chromosome. This investigation indicates the importance of plasmid in spreading of antimicrobial resistance. This research is one of the little data that reported on plasmid mediated antimicrobial resistance determinants in Egypt.

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