Phenotypic and genotypic evaluation of aminoglycoside resistance in Escherichia coli isolated from patients with blood stream infections in Tehran, Iran

Mahsa Ghamari; Mohammad Emaneini; Saeed Hemmati; Fereshteh Jabalameli; Reza Beigverdi

doi:10.18502/ijm.v16i2.15351

Mahsa Ghamari Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Mohammad Emaneini Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Saeed Hemmati Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Fereshteh Jabalameli Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Reza Beigverdi Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran

DOI: https://doi.org/10.18502/ijm.v16i2.15351

Keywords: Aminoglycoside resistance; Escherichia coli; Bacteremia; Aminoglycoside-modifying enzymes

Abstract

Background and Objectives: Escherichia coli is a significant causative agent of bloodstream infections (BSIs). Aminogly- coside antibiotics play a crucial role in treating severe infections such as sepsis and pneumonia. However, resistance to these antibiotics often occurs due to the production of aminoglycoside-modifying enzymes (AMEs). This study was conducted to assess antimicrobial susceptibility patterns against various aminoglycosides and to determine the prevalence of common AME genes in E. coli strains isolated from BSIs.

Materials and Methods: Sixty-five E. coli isolates were obtained from blood samples in a referral hospital in Tehran, Iran. The susceptibility patterns of aminoglycosides were determined using disk diffusion method and AMEs genes were investi- gated using PCR assay.

Results: Resistance to aminoglycosides was observed in 64.6% (42/65) of the isolates. The most frequent resistance rate was found for kanamycin (44.6%) and gentamicin (38.5%), followed by tobramycin (29.2%) and amikacin (4.6%). The most frequent AME gene was aac(3)-IVa, which detected in 49.2% isolates, followed by aac(6)-Ib (40%), aac(3)-IIa (32.3%), and ant(2)-Ia (30.8%), respectively.

Conclusion: Athough the findings of this survey are based on specimens collected from a single hospital, our study shows that the high prevalence of aminoglycoside resistance is primarily attributed to the presence of the aac(3)-Iva, aac(6)-Ib and aac(3)-IIa genes. The low rate of resistance to amikacin makes this antibiotic a good candidate for treatment of BSIs due to E. coli.