| Introduction
Enzymatic inactivation is one of the most important mechanisms of resistance in aminoglycosides.
The aim of this study was to investigate the prevalence of armA and diversity of the genes encoding aminoglycoside-modifying enzymes (AMEs) and their associations with resistance phenotypes in Enterobacteriacae isolates.
Methods: Three hundred and seven Enterobacteriacae isolates were collected from five hospitals in north-west Iran. Disk diffusion method for amikacin, gentamicin, tobramycin, kanamycin and streptomycin, as well as MIC for amikacin, gentamicin, tobramycin and kanamycin was done.
Thirteen AMEs genes and armA methylase were screened using the PCR assay.
Results: Two hundred and twenty (71.7%) of isolates were resistant to aminoglycosides and 155 (70.5%) of them were positive for aminoglycoside resistance genes. The most prevalent AME genes were ant(3')-Іa and aph(3'')-Іb with frequency 35.9% and 30.5%, respectively. Also, twenty-one (9.5%) of resistant isolates were positive for armA methylase gene.
Conclusions: Our study demonstrated AMEs genes frequently are disseminated in Enterobacteriacae isolates in Iran. More than 70% of resistance to aminoglycoside was related to enzymatic inactivation by production AMEs mechanism. In addition to AMEs and methylation of 16S rRNAby armA there are multifarious mechanisms that causes aminoglycoside-resistant phenotypes. |