摘要：Plasmid profiling is among the methods used to determine and characterize antibiotic resistance traits in bacteria. In this study, a total of 80 Escherichia coli isolate from four domestic livestock comprising cattle, goats, poultry and swine in three states of South East Nigeria were screened for antibiotic susceptibility and plasmid profiles. The isolates were tested against 14 antibiotics using the disc diffusion method while plasmid DNA was extracted using the alkaline SDS method and separated by agarose gel electrophoresis. A total of 42 different antibiotic resistance profiles were observed, with each isolate showing resistance to at least four or more drugs tested. Plasmids of different sizes were detected in the isolates. Isolates with high multi-drug resistance profiles were found to possess multiple plasmids with large sizes in the range of 1 to 120 KB. Very high resistance levels (>75%) were detected against Ampicillin, Cotrimaoxazole, Cephalothin and Streptomycin, while Nalidixic acid and Gentamycin recorded the least resistance levels of 16.3 and 12.5% respectively among the isolates. Key word: Plasmid profile, Escherichia coli, Nigeria.
