Genetic diversity and prevalence of aminoglycoside modifying enzymes among Escherichia coli strains isolated from inpatients with urinary tract infections

Abstract

The aminoglycosides are broad-spectrum antibiotics that traditionally prescribed for the treatment of serious Gram-negative infections. The main mechanism of resistance to these antibiotics in Escherichia coli is enzymatic alteration of aminoglycosides by aminoglycoside-modifying enzymes (AMEs). The present study aimed to investigate the genetic diversity and prevalence of aminoglycoside-resistant strains of E. coli isolated from inpatients with urinary tract infection. This cross-sectional study was conducted during September 2018 to March 2019 on a total of 83 non-susceptible aminoglycosides E. coli in the North of Iran. Antimicrobial susceptibility test was performed by disk diffusion method. The presence of genes encoding aminoglycoside modifying enzymes (AMEs) was detected by PCR. The clonal relatedness of E. coli isolates was investigated by ERIC-PCR. Totally, 66.3% and 43.4% of isolates were non-susceptible to gentamicin and amikacin, respectively. The most common AME gene was aac(6′)-Ib (49.4%) followed by aac(3)-II (39.8%), ant(3″)-I (8.4%) and aph(3′)-VI (1.2%). Moreover, aac(6′)-II gene was not found among studied strains. All of the extended-spectrum beta-lactamases (ESBLs) producing isolates (55 isolates) were tested by ERIC-PCR. These isolates were classified into 10 ERIC types, and ERIC type A were the predominate type containing 52.7% of isolates. Findings showed a substantial proportion of AMEs among aminoglycosides-resistant UPEC isolates. Moreover, the clonal analysis showed that a remarkable rate (52.7%) of aminoglycosides-resistant and ESBL-producing isolates was closely related. These findings suggest the necessity of restricted infection control policy to prevent further dissemination of resistant strains.