title: Vancomycin-dependent Enterococcus faecium isolated from stool following oral vancomycin therapy.
abstract: The isolation of clinical strains of enterococci requiring vancomycin for growth has only recently been reported. We describe the isolation of Enterococcus faecium requiring vancomycin for growth from the stool of a patient who had completed oral vancomycin therapy. Growth of the vancomycin-dependent E. faecium was supported by ristocetin and D-alanyl-D-alanine but not by daptomycin, teicoplanin, or D,L-alanine. Spontaneous revertants not requiring vancomycin occurred at a rate of 1 in 10(6). Both the vancomycin-dependent E. faecium and the revertant hybridized with a vanB gene probe and had identical contour-clamped homogeneous electrophoresis patterns. The majority of revertant colonies were resistant to teicoplanin, suggesting constitutive production of the vanB ligase. We believe the vancomycin-dependent E. faecium evolved from a vancomycin-resistant, vancomycin-independent E. faecium in the presence of high concentrations of vancomycin in the intestine.
authors.affiliation: Infectious Diseases Section, Veterans Affairs Medical Center, East Orange, New Jersey 07018, USA.
authors.forename: L L
authors.initials: LL
authors.lastname: Dever
authors.forename: S M
authors.initials: SM
authors.lastname: Smith
authors.forename: S
authors.initials: S
authors.lastname: Handwerger
authors.forename: R H
authors.initials: RH
authors.lastname: Eng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004269:DNA, Bacterial; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D004761:Enterocolitis, Pseudomembranous / Q000150:complications / Q000188:drug therapy; D005243:Feces / Q000382:microbiology*; D016908:Gram-Positive Bacterial Infections / Q000150:complications / Q000382:microbiology*; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D014640:Vancomycin / Q000378:metabolism* / Q000627:therapeutic use
chemical_list: D004269:DNA, Bacterial; D014640:Vancomycin