Abstract

The aim of this study was to characterize the antimicrobial resistance and mechanism of streptomycin-resistance in Escherichia coli isolated from retail meats and eggs during 2012-2013. A total of 76 E. coli isolates were assessed for antimicrobial susceptibility to 14 anti-microbial agents by Disk Diffusion Method. Resistant strains were screened by PCR for streptomycin resistance genes. Each strain was found resistant to at least one antimicrobial and 68 of 76 isolates (89.5%) showed multidrug resistance phenotypes to at least three classes of antimicrobials. The most prevalent resistances were to streptomycin (92.1%), followed by tetracycline (88.2%), ampicillin (81.6%), gentamicin (72.4%), nalidixic acid (69.7%) and sulfadimidine (63.2%). For each streptomycin-resistance gene, the predominant resistance genes were: aadA1 (64.3%), followed by strA/B (51.4%) and aadA2 (41.4%). However, the level of antimicrobial resistance and dissemination of resistance genes differed in E. coli strains with different sources.