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. 2015 Apr 18;8(4):e18102.
doi: 10.5812/jjm.8(4)2015.18102. eCollection 2015 Apr.

Study of aminoglycoside resistance genes in enterococcus and salmonella strains isolated from ilam and milad hospitals, iran

Nasser Samadi  1 , Iraj Pakzad  2 , Alireza Monadi Sefidan  3 , Hasan Hosainzadegan  4 , Asghar Tanomand  4
Affiliations

Study of aminoglycoside resistance genes in enterococcus and salmonella strains isolated from ilam and milad hospitals, iran

Nasser Samadi et al. Jundishapur J Microbiol. .

Abstract

Background: Aminoglycosides are a group of antibiotics that have been widely used in the treatment of life-threatening infections of Gram-negative bacteria.

Objectives: This study aimed to evaluate the frequency of aminoglycoside resistance genes in Enterococcus and Salmonella strains isolated from clinical samples by PCR.

Materials and 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.

Keywords: Aminoglycoside; Enterococcus; Genes; Salmonella.

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Figures

Figure 1.
Figure 1.. Electrophoresis Profile of the Polymerase Chain Reaction Products of Clinical Enterococcus Isolates Containing Aminoglycoside Resistance Genes
Lane 1: 100 base pair (bp) marker; lanes 2, 4 and 6: positive controls for aminoglycoside genes, Lanes 3, 5 and 7: clinical isolates containing aminoglycoside genes.
See this image and copyright information in PMC

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