Tow most important mechanisms of resistance to aminoglycosides among Enterobacteriaceae isolates

Background: Enzymatic inactivation and 16S rRNA methylation are the most important mechanisms of resistance to aminoglycosides. The aim of this study was to evaluate the diversity and prevalence of the genes encoding aminoglycoside-modifying enzymes (AMEs) and 16S rRNA methylase and their associations with resistance phenotypes in Enterobacteriacae isolates. Methods: A total of 307 non-duplicate clinical Enterobacteriaceae isolates were collected from five hospitals in Northwest of Iran. The disk diffusion methods as well as the MIC for amikacin, gentamicin, tobramycin and kanamycin were done for susceptibility testing. Thirteen AMEs genes and six 16S rRNA methylase genes were screened using the PCR and sequencing assays. Results: Based on the results, 220 (71.7%) of isolates were resistant to aminoglycosides. One hundred and fifty-five (70.5%) and 40 (18.2%) of them were positive for AMEs and 16S rRNA methylase genes, respectively. The ant (3 )-Іa (35.9%) and aph (3 )-Іb (30.5%) also armA (9.5%) and rmtC (4.5%) were the most prevalent AMEs and 16S rRNA methylase genes, respectively. Conclusions: Many of genes encoding AMEs and 16S rRNA methylase are disseminated in Enterobacteriacae isolates in Iran. There is an association between phenotypic resistance and the presence of some aminoglycoside genes. Furthermore, there is a statistically significant association resistance to aminoglycosides and the presence of some genes.

کلیدواژه ها:

Aminoglycoside-modifying enzymes ، Enterobacteriacae ، 16S rRNA