O-24: Difference of Clonality between High Level Gentamicin Resistant (HLGR) E.Faecium and E.Faecalis Species Isolated from Clinical Specimens in Tehran


Dadfarma N *, Imani Fooladi AA , Oskoui M ,

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Objective: Major antimicrobial resistance problems are typically associated with gram-positive nosocomial pathogens.Increasingly, hospital-acquired infections with multidrug-resistant enterococci represent a major problem for the treatment of bacterial infections in patients. In addition to natural resistance to many agents, enterococci have also developed plasmid- and transposon-mediated resistance to high concentrations of aminoglycosides. High-level resistance to gentamicin HLGR (MIC≥500μg/ml) in enterococci is usually due to the presence of the aac(6′)Ie-aph(2″)Ia gene. This gene conferred resistance to synergism between gentamicin and cell-wall active agents and detected than strains producing the bifunctional enzyme.In this study we compared clonal diversity between enterococcus species. Materials and Methods: 142 strains were isolated from patients in Tehran during May and Septamber 2009. Identification performed with biochemical tests. disc diffusion method used to confirm HLGR with gentamicin disk (120μg). PCR was performed to detect of the aac (6′) Ie-aph (2″) Ia gene with specific primers. Clonality was determined by pulsed-field gel electrophoresis (PFGE),with the restriction enzyme SmaI. Results: Among the 142 enterococcal isolates, 87 E. faecalis, 49 E. faecium, 6 other species were detected. 60 isolates (42%) exhibited HLGR phenotype. 59 isolates were found to carry the aac(6′)Ie-aph(2″)Ia gene, In our strain collection, 43% of E.faecalis and 41% of E.faecium were HLGR.In HLGR isolates 37 E.faecalis and 20 E.faecium were resolved into 5 and 11 clons, respectively. Similar clonality in E.faecalis was more than E.faecium Conclusion: PFGE of E. faecium species with HLR to gentamicin had different restriction endonuclease digestion patterns. spread of microclones containing identical or closely related isolates was identified in faecalis species.unique genotype profiles by PFGE for some of the E.faecalis isolates analysed indicates that they were of endogenous origin and dissemination of genetically related strains in hospital can be occured. the general intraspecies genomic variation seen in faecium isolates