A cluster of VanD vancomycin-resistant Enterococcus faecium: Molecular characterization and clinical epidemiology

Abstract

VanD-mediated glycopeptide resistance has been reported for an isolate of Enterococcus faecium, BM4339. Three clinical isolates of vancomycin- resistant E. faecium collected from 3 patients during a 6-week period in 1993 had agar dilution MICs of vancomycin and teicoplanin of 128 and 4 μg/mL, respectively. Polymerase chain reaction (PCR) using degenerate primers complementary to genes encoding D-Ala-D-X ligases yielded a 630-bp product that was similar to the published partial sequence of vanD. By use of inverse PCR, vanD, vanH(D), and two partial flanking open-reading frames were sequenced. The deduced amino acid sequence of VanD showed 67% identity with VanA and VanB. vanD appeared to be located on the chromosome and was not transferable to other enterococci. The 3 isolates were indistinguishable by pulsed-field gel electrophoresis and differed from BM4339. No other isolates carrying rand were found in a subset of 875 recent US isolates of vancomycin- resistant enterococci.