A DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN MOLECULAR BIOLOGY AND BIOTECHNOLOGY OF
SOKOINE UNIVERSITY OF AGRICULTURE.
MOROGORO, TANZANIA
The poultry industry, especially chicken production has in recent times faced a major set-back due to devastating effects of Extended Spectrum Beta-Lactases (ESBL) producing organisms.This research aimed at investigating the diversity of ESBL genes in avian pathogenic Escherichia coli(APEC) among scavenging local chickens. A total of 400 cloacal and oropharyngeal swabs were obtained, out of which 192 Escherichia coli were isolated. By use of virulence factor profiling, these 192 samples were screened for the presence of 16 virulence factors by multiplex PCR. All 192 samples harbored at least one of the 16 virulence genes and 19 of them carried at least four, making them APEC. The virulence traits ibeA, iss, traT and chuA were observed to lead the chart with percentages of 84.21, 78.95, 63.16 and and 52.63respectively. In the pathogenesis of APEC, Iron acquisition, serum resistance, toxins and invasins were found to be very significant (P<0.05). The antimicrobial profiles of these APEC strains were determined by Kirby-Bauerdisc diffusion test using 10 antimicrobials. These include:augmentin (30μg), imipenem (10μg), cephalothin (30μg), cefotaxime (30μg), ceftazadime (30μg), ceftriaxone (30μg), nalidixic acid (30μg), ciprofloxacin (5μg), gentamycin (10μg) and trimethroprim-sulfamethoxazole(25μg). All APEC strains were found to be resistant to at least one of these drugs, with 10.52% of them being multi-drug resistant. By double-disc synergy test, eight of the APEC isolates were found to be ESBL producers. They were screened for the presence of beta-lactamase genes and the following were present: blaTEM-100%, blaOXA-1 -75.0%, blaCMY-2 62.5%, CTX-M group III (CTX-M-8)-50%, CTX-Mgroup IV (CTX-M -9)-37.5%, CTX-M group I(CTX-M -1,and-15) -12.5% and blaSHV-12.5%. Occurrence of virulence strains of APEC and ESBLs genes are also alarming