Braak, van den N.P.W.C.J. (Nicole)Belkum, van A.F. (Alex)Kreft, D.Witt, te R. (René)Verbrugh, H.A. (Henri)Endtz, H.P. (Hubert)HumansElectrophoresis, Gel, Pulsed-FieldPolymerase Chain Reaction/methodsMicrobial Sensitivity TestsAnti-Bacterial Agents/*pharmacologyCulture MediaHospitals, UniversityBacteremia/epidemiology/microbiologyDNA, Bacterial/analysisDrug Resistance, Microbial/geneticsEnterococcus/*drug effects/*genetics/isolation & purificationGentamicins/*pharmacologyGram-Positive Bacterial Infections/*epidemiology/*microbiologyhttp://hdl.handle.net/1765/9210enjournalArticle0305-7453We studied the prevalence and clonality of high-level gentamicin-resistant enterococci (HLGRE) in a Dutch university hospital. Of 238 enterococcal strains isolated from blood cultures between 1991 and 1997, 57 were HLGRE. Genomic analysis of these strains revealed 19 different genotypes, two of which were encountered more frequently [type A (12/57), type B (23/57)]. The spread of these types largely explained the rise in HLGRE incidence from 14% in 1991 to 31% in 1997. However, the contribution of unique strains to the total HLGRE burden also increased from 4% to 16%. We conclude that both clonal expansion and the emergence of unique HLGRE have contributed significantly to the increasing incidence of HLGRE.1999-01-01 0305-7453 urn:NBN:nl:ui:15-1765/9210