title: Study of aminoglycoside resistance genes in enterococcus and salmonella strains isolated from ilam and milad hospitals, iran.
abstract: BACKGROUND
  Aminoglycosides are a group of antibiotics that have been widely used in the treatment of life-threatening infections of Gram-negative bacteria.
  
  
  OBJECTIVE
  This study aimed to evaluate the frequency of aminoglycoside resistance genes in Enterococcus and Salmonella strains isolated from clinical samples by PCR.
  
  
  METHODS
  In this study, 140 and 79 isolates of Enterococcus and Salmonella were collected, respectively. After phenotypic biochemical confirmation, 117 and 77 isolates were identified as Enterococcus and Salmonella, respectively. After the biochemical identification of the isolates, antibiotic susceptibility for screening of resistance was done using the Kirby-Bauer method for gentamicin, amikacin, kanamycin, tobramycin and netilmycin. DNA was extracted from resistant strains and the presence of acc (3)-Ia, aac (3')-Ib, acc (6)-IIa ,16SrRNA methylase genes (armA and rat) was detected by PCR amplification using special primers and positive controls.
  
  
  RESULTS
  Enterococcus isolates have the highest prevalence of resistance to both kanamycin and amikacin (68.4%), and Salmonella isolates have the highest prevalence of resistance against kanamycin (6.9%). Ninety-three and 26 isolates of Enterococcus and Salmonella at least were resistant against one of the aminoglycosides, respectively. Moreover, 72.04%, 66.7%, and 36.6% of the resistant strains of Enterococcus had the aac (3')-Ia, aac (3')-IIa, and acc (6')-Ib genes, respectively. None of the Salmonella isolates have the studied aminoglycoside genes.
  
  
  CONCLUSIONS
  Our results indicate that acetylation genes have an important role in aminoglycoside resistance of the Enterococcus isolates from clinical samples. Moreover, Salmonella strains indicate very low level of aminoglycoside resistance, and aminoglycoside resistance genes were not found in Salmonella isolates. These results indicate that other resistance mechanisms, including efflux pumps have an important role in aminoglycoside resistance of Salmonella.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, IR Iran.
authors.forename: Nasser
authors.initials: N
authors.lastname: Samadi
authors.affiliation: Department of Microbiology, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, IR Iran ; Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, IR Iran.
authors.forename: Iraj
authors.initials: I
authors.lastname: Pakzad
authors.affiliation: Department of Microbiology, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Monadi Sefidan
authors.affiliation: Department of Basic Sciences, Faculty Of Medicine, Maragheh University of Medical Science, Maragheh , IR Iran.
authors.forename: Hasan
authors.initials: H
authors.lastname: Hosainzadegan
authors.affiliation: Department of Basic Sciences, Faculty Of Medicine, Maragheh University of Medical Science, Maragheh , IR Iran.
authors.forename: Asghar
authors.initials: A
authors.lastname: Tanomand
keywords: Aminoglycoside; Enterococcus; Genes; Salmonella