evaluation of genetic pattern of gentamicin-resistant enterococci isolated from clinical samples

background and aims. enterococci are among resistant microorganisms to antibiotics and are responsible for some of acute gingival infections. this study aimed at molecular evaluation of gentamicin-resistant enterococcus species and determining the resistance genes. materials and methods. clinical samples were cultured on bhi medium and enterococci were isolated by specific methods and antibiograms were prepared. dna was derived from gentamicin-resistant species by alkaline lysis method and replicated by pcr method. four gentamicin-resistant genes were evaluated by electrophoresis method on agarose gel. results. from 105 enterococcus faecalis isolates, 36.2% and from 38 enterococcus faecium isolates, 78.2% were resistant to gentamicin. 60% of these species bore aac (6’)- le – aph(2”)- la gene. ph(2”)- ib,ic,id genes were not seen in any of the evaluated species. conclusion. in gentamicin-resistant species of e. faecalis and e. faecium, the aac (6’)- le – aph(2”)- la gene was identified as the main cause of resistance.