Abstract: This study was carried out to investigate the prevalence of fluoroquinolone resistance and plasmid carriage among isolates of commensal E. coli isolated from faeces of cattle. Fresh faecal samples were collected from apparently healthy cattle and were cultured on eosine methylene blue agar plates from which 500 commensal E. coli isolates were recovered and characterised using standard biochemical tests. Using protocol recommended by the Clinical Laboratory Science Institute, all isolates were examined for their susceptibility to five fluoroquinolones: norfloxacine (5 μg), levofloxacine (5 μg), pefloxacine (5 μg), ofloxacine (5 μg) and ciprofloxacine (5 μg). The resistance among isolates against the fluoroquinolones are as follows: pefloxacine, 99 (19.8%); ciprofloxacine, 55 (11.0%); norfloxacine, 39 (7.5%); ofloxacine 26 (5.2%) while the isolates showed least resistance against levofloxacine 23 (4.6%). The organisms also showed considerable multiple fluoroquinolone-resistance and sixteen different fluoroquinolone-resistance phenotypes were observed with the most prominent phenotype observed to be Cip-Nor-Ofx-Pef-Lev. Thirteen representative isolates were selected and examined for the presence of plasmids. Twelve of the representative isolates carried multiple plasmids while one isolate carried a single plasmid. After mating experiments, plasmids were transferred to recipient strains at high frequencies of conjugation. These findings have serious public health implications as fluoroquinolone-resistant bacteria could be shed into the immediate environments, food and drinking water sources.
A.O. Ajayi, O.A. Olowe and O. Famurewa, 2011. Plasmid Analysis of Fluoroquinolone Resistant Commensal E. coli from Faecal Samples of Apparently Healthy Cattle in Ado-Ekiti, Ekiti-State. Journal of Animal and Veterinary Advances, 10: 180-184.