Frequency distribution of genes encoding aminoglycoside modifying enzymes in uropathogenic E. coli isolated from Iranian hospital.

BACKGROUND: Escherichia coli is considered as the most common cause of urinary tract infection (UTI) and acquired multiple resistances to a wide range of antibiotics such as aminoglycosides. Enzymatic alteration of aminoglycosides (AMEs) by aminoglycoside- modifying enzymes is the main mechanism of resistance to these antibiotics in E. coli. The aim of this study was detection and investigation of frequency of genes encoding aminoglycoside modifying enzymes (aac(3)-IIa and ant(2'')-Ia) in UPEC isolated from hospitalized patients in teaching hospital of Tehran, Iran.

FINDINGS: A total of 276 UPEC were obtained from Urine samples in a hospital from Tehran. Antibiotic susceptibility to aminoglycosides was determined by disk diffusion method according CLSI guidelines in UPEC isolates. MICs of target antibiotics were determined by agar dilution method. All isolates were screened for the presence of the AMEs genes using the PCR. The results of disk diffusion showed 21%, 24.6%, 23.18%, 3.62% and 6.15% of isolates were resistant to Gentamicin, Tobramycin, Kanamicin, Amikacin and Netilmicin respectively. The agar dilution's results (MICs) were high, 66.19% for Gentamicin. The aac (3)-IIa and ant(2″)-Ia genes were detected in (78.87%) and 47.88% of isolates respectively.

CONCLUSIONS: This study shows the high frequency of genes encoding (AMEs) aac(3)-IIa and ant(2")-Ia genes and their relationship between different aminoglycoside resistance phenotypes.