title: D-Ala-d-Ser VanN-type transferable vancomycin resistance in Enterococcus faecium.
abstract: Enterococcus faecium UCN71, isolated from a blood culture, was resistant to low levels of vancomycin (MIC, 16 μg/ml) but susceptible to teicoplanin (MIC, 0.5 μg/ml). No amplification was observed with primers specific for the previously described glycopeptide resistance ligase genes, but a PCR product corresponding to a gene called vanN was obtained using degenerate primers and was sequenced. The deduced VanN protein was related (65% identity) to the d-alanine:d-serine VanL ligase. The organization of the vanN gene cluster, determined using degenerate primers and by thermal asymmetric interlaced (TAIL)-PCR, was similar to that of the vanC operons. A single promoter upstream from the resistance operon was identified by rapid amplification of cDNA ends (RACE)-PCR. The presence of peptidoglycan precursors ending in d-serine and d,d-peptidase activities in the absence of vancomycin indicated constitutive expression of the resistance operon. VanN-type resistance was transferable by conjugation to E. faecium. This is the first report of transferable d-Ala-d-Ser-type resistance in E. faecium.
authors.affiliation: Interactions Hôte et Microorganismes des Epithéliums, EA2128, CHU Côte de Nacre, 14033 Caen Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Lebreton
authors.forename: Florence
authors.initials: F
authors.lastname: Depardieu
authors.forename: Nancy
authors.initials: N
authors.lastname: Bourdon
authors.forename: Marguerite
authors.initials: M
authors.lastname: Fines-Guyon
authors.forename: Pierre
authors.initials: P
authors.lastname: Berger
authors.forename: Sabine
authors.initials: S
authors.lastname: Camiade
authors.forename: Roland
authors.initials: R
authors.lastname: Leclercq
authors.forename: Patrice
authors.initials: P
authors.lastname: Courvalin
authors.forename: Vincent
authors.initials: V
authors.lastname: Cattoir
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D016984:Enterococcus faecium / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D005810:Multigene Family; D010453:Peptide Synthases / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017334:Teicoplanin / Q000494:pharmacology; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D017334:Teicoplanin; D014640:Vancomycin; D010453:Peptide Synthases; C108395:VanC protein, Enterococcus