Heterogeneity of Aminoglycoside Resistance Patterns among Fecal Escherichia Coli Strains Isolated from Animal and Human Sources in Alborz Province, Iran

Escherichia coli is recognized as a major food-borne pathogen in humans worldwide. Antibiotic resistance of Escherichia coli isolates is a concern that has created widespread problem for treatment of infections caused by this bacterium. The aim of this study was to determine the pattern of aminoglycoside resistance among the strains of Escherichia coli isolated from animal and human sources in the Alborz province, Iran.

The strains of Escherichia coli were recovered from keeping animals (dairies, beekeeping and sheep care center) and 2 laboratory facilities in Alborz province. These isolates were identified using standard biochemical and bacteriological tests. Susceptibility and antibiotic resistance of isolates were determined via disk diffusion method.

Eighty isolates of Escherichia coli were isolated and included in the study. The total rates of antibiotic resistance of the isolates were as 72.5% to streptomycin, 13.75% to neomycin, and 6.25% to tobramycin and gentamicin; none of the isolates showed resistance to amikacin. Based on the source of the isolation, resistance rates to streptomycin was 95%, 85%, 65% and 45% in the isolates recovered from human, cow, chicken and sheep, respectively. The resistance rates to neomycin among the strains isolated from cow, sheep and chicken were 5%, 15% and 25%, respectively. Only 25% of the isolates recovered from chicken were resistant to gentamicin and tobramycin.

This study showed a diversity of aminoglycoside resistance among isolates of Escherichia coli recovered from different sources. While aminoglycoside resistance of Escherichia coli is varied among different sources of isolation, continuous monitoring of resistance patterns and the use of antibiotic agents according to the sources of isolation is recommended.