Characterization of antibiotic resistance integrons harbored by Romanian Escherichia coli uropathogenic strains

Because little is known about the integrons which constitute an important means of spreading resistance in bacteria circulating in Romania, this study aimed to detect antibiotic resistance gene cassettes embedded in integrons in a convenient collection of 60 ciprofloxacin-resistant Escherichia coli isolates of various phylogroups, associated with community-acquired urinary tract infections. Characterization of the integrons was accomplished by PCR, restriction fragment length polymorphism typing, and DNA sequencing of each identified type. More than half of the tested E. coli strains were positive for integrons of class 1 (31 strains) or 2 (1 strain). These strains derived more frequently from phylogenetic groups A (15 of 21 strains), B1 (10 of 14 strains), and F (3 of 4 strains), respectively. While 20 strains carried class 1 integrons which could be assigned to nine types, eleven strains carried integrons that lacked the 3’-end conserved segment. The attempts made to characterize the gene cassettes located within the variable region of the various integrons identified in this study revealed the presence of genes encoding resistance to trimethoprim, aminoglycosides, beta-lactams or chloramphenicol. The evidence of transferable resistance determinants already established in the autochthonous E. coli strains highlights the need for improved control of resistance-carrying bacteria.