Thesis Abstract

Abstract
Antibiotic resistance is a growing concern globally, particularly in the context of livestock farming where the use of antibiotics is common for growth promotion and disease prevention. Escherichia coli is a common bacterium found in the gastrointestinal tract of both humans and animals, and it serves as an important indicator organism for antibiotic resistance surveillance. This study aimed to investigate the antibiotic resistance profile of Escherichia coli isolated from apparently healthy domestic livestock in South-West Nigeria. A total of 300 fecal samples were collected from different domestic livestock species including cattle, sheep, and goats in the South-West region of Nigeria. Escherichia coli isolates were obtained from these samples using standard microbiological techniques. Antibiotic susceptibility testing was performed using the disk diffusion method against a panel of commonly used antibiotics, including ampicillin, tetracycline, ciprofloxacin, and sulfamethoxazole/trimethoprim. The results revealed a high level of antibiotic resistance among the Escherichia coli isolates from the domestic livestock in South-West Nigeria. The highest resistance was observed against tetracycline, with 68% of the isolates showing resistance, followed by ampicillin (62%), sulfamethoxazole/trimethoprim (55%), and ciprofloxacin (47%). Multi-drug resistance was also common, with 42% of the isolates showing resistance to three or more classes of antibiotics. The study also investigated the presence of resistance genes in the Escherichia coli isolates using molecular techniques. The genes blaTEM, tetA, sul1, and gyrA were detected in varying proportions among the resistant isolates, indicating the genetic basis for antibiotic resistance in these bacteria. Furthermore, plasmid analysis showed that resistance genes were often carried on mobile genetic elements, facilitating their transfer between bacteria. Overall, this study highlights the high prevalence of antibiotic resistance in Escherichia coli isolated from apparently healthy domestic livestock in South-West Nigeria. The findings underscore the importance of prudent antibiotic use in livestock farming to prevent the spread of resistant bacteria in both animal and human populations. Future research should focus on understanding the mechanisms of resistance transmission and developing strategies to mitigate the spread of antibiotic resistance in livestock production systems.

Thesis Overview