Characterization of antimicrobial resistance and class 1 integrons found in Escherichia coli isolates from human...

This study demonstrates that Escherichia coli isolates from human stools showed mostly higher minimum inhibitory concentrations (MICs) and significant rates of resistance (32%-67%, P<0.05) than Escherichia coli water isolates in Jordan, as follows: ampicillin (67% vs 28%), trimethoprim/sulfamethoxazole (67% vs 28%) nalidixic acid (63% vs 20%), cefuroxime (32% vs 4%), gentamicin (32% vs 17%), norfloxacin (32% vs 12%) and tetracycline (33% vs 16%). The prevalence of integron integrase genes (Intl1) in these isolates was also significantly higher in patients' stools (67%, P <0.05) than in water (36%), but the distribution of Sul 1/Sul 2 or both in association with postive Intl1 and resistance to ampicillin and sulfamethoxazole was not significantly higher (74% versus 62%, P <0.05) in isolates from stool and water. Plasmid profiles of representative multiresistant E. coli isolates from both sources indicated the presence of two common plasmids (49,25 kb) in 11/12 (91.6%), and all E. coli transconjugants were positive for class 1 integron markers (Intl 1, Sul 1 and Sul2) and mostly associated with three transferable drug-resistant determinants to ampicillin, sulfamethoxazole and tetracycline. These results indicate that class 1 integrons with conjugative R-plasmids are common and transferable among commensal antimicrobial multiresistant E. coli isolated from human feces and drinking water sources in Jordan.