In vitro characterization of multiple-drug-resistant diarrheagenic avian Escherichia coli isolates

Indiscriminate antimicrobial usage is considered to be the most important factor promoting the emergence, selection and dissemination of antibiotic resistant microorganisms. This report summarizes the in vitro antimicrobial resistance patterns of Escherichia coli strains isolated from diarrheic fecal and environmental samples of different poultry farms. A total of 54 E. coli isolates were tested against 21 antimicrobials and were multiple drug resistant (MDR). The degree of MDR ranged from 8 to 21 antimicrobial agents. Avian E. coli isolates expressed resistance to the β-lactams, ampicillin and amoxycillin at frequencies of 62.96% and 61.11%, respectively. Of the aminoglycosides included in the panel, the susceptibility results varied with different antimicrobials. Isolates expressed highest resistance to kanamycin (87.04%) and least to tobramycin (35.18%). The study highlighted the prevalence of MDR E. coli among poultry, which may colonize the human intestinal tract via food and may also contribute resistance genes to human endogenous flora. Therefore, high prevalence of antimicrobial resistance detected during the study is a matter of concern and the cautious use of antibiotics in animals is recommended.