Dissemination of Genes Encoding Aminoglycoside-Modifying Enzymes and armA Among Enterobacteriaceae Isolates in Northwest Iran.
BACKGROUND
Enzymatic inactivation is one of the most important mechanisms of resistance to 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 Enterobacteriaceae isolates.


METHODS
Three hundred and seven Enterobacteriaceae isolates were collected from five hospitals in northwest Iran. The disk diffusion method for amikacin, gentamicin, tobramycin, kanamycin, and streptomycin, as well as the minimum inhibitory concentration for amikacin, gentamicin, tobramycin, and kanamycin were done for susceptibility testing. Thirteen AME genes and armA methylase were screened using the PCR and sequencing assays.


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″)-Ia and aph(3″)-Ib with the frequency 35.9% and 30.5%, respectively. Also, 21 (9.5%) of resistant isolates were positive for armA methylase gene.


CONCLUSIONS
The prevalence of resistance to aminoglycoside is high and AME genes frequently are disseminated in Enterobacteriaceae isolates. There is an association between phenotypic resistance and the presence of some aminoglycoside genes.
1 Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences , Tabriz, Iran .|2 Department of Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences , Tabriz, Iran .
Reza
R
Ghotaslou
1 Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences , Tabriz, Iran .|2 Department of Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences , Tabriz, Iran .
Fatemeh
F
Yeganeh Sefidan
2 Department of Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences , Tabriz, Iran .
Mohammad Taghi
MT
Akhi
3 Department of Laboratory Sciences, Paramedical Faculty and Biotechnology Research Center, Tabriz University of Medical Sciences , Tabriz, Iran .
Mohammad
M
Asgharzadeh
2 Department of Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences , Tabriz, Iran .
Yalda
Y
Mohammadzadeh Asl
D000583:Amikacin / Q000494:pharmacology; D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004755:Enterobacteriaceae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005839:Gentamicins / Q000494:pharmacology; D006761:Hospitals; D006801:Humans; D007492:Iran / Q000453:epidemiology; D007612:Kanamycin / Q000494:pharmacology; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D017422:Sequence Analysis, DNA; D013307:Streptomycin / Q000494:pharmacology; D014031:Tobramycin / Q000494:pharmacology
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D005839:Gentamicins; D007612:Kanamycin; D000583:Amikacin; C506767:ArmA protein, E coli; D008780:Methyltransferases; D014031:Tobramycin; D013307:Streptomycin
Enterobacteriaceae; aminoglycoside-modifying enzymes; armA