| Abstract: |
A total of 148 Escherichia coli isolates from chickens were identifiedbiochemically as Escherichia coli by lactose fermentation, indole, citrate, methyl red and V.P tests, their pathogenicity were identified byserum resistance test. These isolates were studied for antimicrobialsusceptibility patterns by disk diffusion method. By the time ofanalyzing the plasmid profiles, 54 out of 148 isolates were examinedfor antimicrobial susceptibility patterns by agar dilution method. Of the 54 isolates, 36 isolates were examined for plasmid profiling by rapidalkaline plasmid isolation and agarose gel electrophoresis.The prevalence of antimicrobial resistance among 148 Escherichia coli.icolates were 29 (19.6%) to cefotaxime, 35 (23.7%) to ceftiofur, 51(34.5%) to gentamicin, 58 (39.2%) to norfloxacin, 75 (50.6%) tociprofloxacin, 103 (69.6%) to chloramphenicol, 105 (70.9%) toenrofloxacin, 117 (79.1 0/0) to streptomycin, 118 (79.7%) tospectinomycin, 124 (83.8%) to trimethoprim/sulfamethoxazole, 136(91.9%) to ampicillin and 143 (96.6%) to doxycycline.In my study high prevalence of multiresistant isolates occurred amongEscherichia coli from chickens, 103 (69.5%) out of all isolates wereresistant to 6 or more out of 12 tested antimicrobial agents.As a result of repeated cultivation and storage in absence of a selectivepressure some isolates lost some resistance markers. Among 54selected isolates, 9 (82%) of 11 cefotaxime resistant isolates becamecompletely susceptible, meanwhile, of 17 ceftiofur resistant isolates, 4(23.5%) became completely susceptible, and 3 (17.5%) became intermediately susceptible. On the contrary, norfloxacin and ciprofloxacin resistances were stab le, moreover, 10 of 12 norfloxacin intermediately susceptible became resistant. The rate of losinggentamicin, spectinomycin, streptomycin and doxycycline among resistant Escherichia coli isolates were 11 %, 15%, 9%, 10.5%, 10.5% and 2%, respectively.
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