Objective: Determine the antimicrobial susceptibility and plasmid profiles of the Escherichia co/i isolates from avian colibacillosis.
Design: Exploratory study.
Samples: One-hundred and fifty Escherichia co/i isolates from broilers pericarditis lesions (5 samples from each of
30 farms).
Procedure: Determine resistance to 20 antibacterial drugs and also determine plasmid profiles among E. coli isolates.
Results: All isolates were susceptible to ceftiofur and gentamicin. The percentages of isolates that were resistant to the other 18 antibacterial agents were as follows: nalidixic acid, 98.7; erythromycin, 97.3; ampicilin, 96.7; colistin, 96.7; tetracycline, 94; flumequine, 92; oxytetracycline, 90.7; difloxacin, 84; nitrofurantoin, 81.3;
forazolidone, 79.3; sulfamethoxazol & trimethoprim, 72.6; enrofloxacin, 66; lincospectin, 64.7; norfloxacin, 52.7; necimycin, 52; chloramphenicol, 46.7; ciprofloxacin, 44; and streptomycine, 26.7. There were 82 resistance patterns among the isolates to 10 most commonly used drugs in poultry industry. Eighty-six isolates (57.2 %) belonged to more than one pattern, whereas the remaining 64 isolates (427%), each belonged to one pattern only. Plasmid profiles revealed 62 patterns in which molecular weights of the plasmid pecies ranged between 1- >68 Kb. No plasmid bands were found in 12 isolates.
Conclusion: Neither drug resistance pattern, nor plasmid
profile could be used as a marker of avian colibacillosis E. coli but plasmid profiles and drug resistnace pattern were useful in distinguishing among isolates from the same farm. J.Fac. Vet.Med. Univ. Tehran. 60,2:97-105,2005.