Detection of vancomycin-resistance genes and virulence factors in vancomycin-resistant enterococci isolated from patients hospitalised in a large university clinical hospital during a two-year period
Abstract number: r1959
Przybylski M., Marchel H., Rudnicka J., Wroblewska M., Luczak M.
Our aim was to analyze group of 98 vancomycin-resistant enterococci (VRE) strains isolated from patients hospitalized in large university clinical hospital in Warsaw, Poland during two-year period (20002002). Strains were isolated from blood, wound, peritoneal cavity, bile and feces. We tested VRE strains for their ampicillin and glycopeptides susceptibility, type of van genes carried and presence of enterococcal virulence factors genes.
Strains were identified with commercial API identification system (bioMerieux) and subsequently checked for species-specific Enterococcus faecium and Enterococcus faecalis ddl genes by PCR. MIC for ampicillin, vancomycin and teicoplanin was determined according to CLSI standards. PCR was used for van genes detection using primers for vanA, vanB, vanC and vanD genes. Virulence factors genes were detected using PCR method with primers specific for five genes from cytolysin complex, gelatinase (gelE), aggregation substance (agg), enterococcal protein A (AefaAfs, efaAfm) and enterococcal surface protein (esp) genes.
Among 98 strains of VRE, the most prevalent was E. faecium (82.7%), according to biochemical identification results. Other VRE species embraced E. faecium, E. durans, E gallinarum and two strains considered as Enterococcus spp. There was discrepancy between identification results using phenotypic and genetic methods in case of 11.2% of strains. Resistance to teicoplanin was detected in 96.9% of strains. Three strains of VRE were ampicillin susceptible. The most prevalent glycopeptide resistance gene was vanA (92.9% of VRE strains). Other types of glycopeptide resistance genes were vanB (three strains) and vanD (one strain). In two strains of VRE, we were unable to detect any van gene. The most prevalent virulence factor gene was efaA (88.8% of strains). Other virulence factors genes were also present: esp in 72.4 % of strains, gelE (12.2%) and agg (10.2%). Various genes of cytolysin complex were found in 11.2% of strains, but there was no strain carrying complete set of cyl genes.
Basing on obtained results, we can assume, that there was multiple insertion of different VRE strains into hospital environment during analyzed two-years period. We also characterized two groups of epidemic strains, and 7 groups of VRE, which were not responsible for epidemic infections. Only in case of esp gene we were able to find significant correlation between site of infection (blood) and carried virulence factor (U-test, p < 0.01).
|Session name:||XXIst ISTH Congress|
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