[An outbreak of vanA genotype Enterococcus faecium in pediatric clinic of a training hospital]

Abstract

Vancomycin-resistant enterococci (VRE) have been increasingly reported from most countries around the world following initial isolation from patients in United States and European countries. A vancomycin-resistant Enterococcus faecium (VREF) outbreak was determined by hospital infection control committee in the pediatric unit of Gulhane Military Medical Academy, Ankara, Turkey in the first week of March 2008. While one of the 4 VREF strains was isolated from urine culture of a patient with neuroblastoma, the remaining strains were isolated from cultures of urine and rectal swab samples of a patient with nephrotic syndrome and from the hospital room doorknob of this patient. Aims of this study were to determine antibiotic susceptibilities by E-test, to investigate the presence of vanA, vanB and vanC-2 resistance genes by polymerase chain reaction (PCR), and to genotype the 4 strains by pulsed field gel electrophoresis (PFGE) and repetitive PCR (rep-PCR) (DiversiLab, bioMérieux, France). All isolates conferred high level [minimum inhibitor concentration (MIC) > 256 mg/L] vancomycin and teicoplanin resistance by E-test method. The isolates were also found resistant to gentamicin, streptomycin, ampicillin, erythromycin, penicillin and were susceptible to tetracycline and linezolid. The vanA gene was detected in all strains by PCR. It was demonstrated that the 4 VRE strains belonged to a single clone as shown by both PFGE and rep-PCR methods. Prompt and accurate detection of VRE and determination of the genotypes is of crucial importance to prevent horizontal transfer of the strains in the hospital. When compared with PFGE, the DiversiLab commercial rep-PCR seems to be a reliable and more rapid method to detect the genetic relationship between strains leading to an outbreak.