Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 16 2 2024 04 19 187 192 EN 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 2023 11 11 2024 02 10 Background and Objectives: Escherichia coli is a significant causative agent of bloodstream infections (BSIs). Aminoglycoside 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 investigated 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. https://ijm.tums.ac.ir/index.php/ijm/article/view/4479 https://ijm.tums.ac.ir/index.php/ijm/article/download/4479/1654