Genotypic characterisation of endemic VanA Enterococcus faecium strains isolated in a paediatric hospital

Service de Microbiologie, Hôpital Robert Debré, 75019 Paris and Laboratoire d'Etudes de Génétique Bacteriénne dans les infections de l'Enfant (EA3105), Université Denis Diderot, Paris 7, France Corresponding author: Professor E. Bingen (e-mail: edouard.bingen{at}rdb.ap-hop-paris.fr ). Received 25 May 1999; revised version accepted 27 Jan. 2000. Abstract A total of 36 vancomycin-resistant Enterococcus faecium isolates obtained from 30 patients during a 28-month period in a paediatric university hospital was analysed by pulsed-field gel electrophoresis (PFGE) combined with Southern hybridisation of a van A-specific DNA probe. All the isolates hybridised with the van A probe. Seventeen different PFGE patterns and 11 PFGE subtypes were identified among the 36 clinical isolates, and the size of probe-positive bands ranged from c . 30 to 300 kb. These data are consistent with an increase in the overall genomic diversity of vancomycin-resistant E. faecium isolates during the study period. Two periods were distinguished. The prevalence of a single clone in the initial period suggested transmission between patients in three wards. During the following period, multiple genotypes of vancomycin-resistant E. faecium were identified, indicative of multiple introductions or the dissemination of resistance genes by recombinant transposition.