title: Expression of glycopeptide-resistance gene in response to vancomycin and teicoplanin in the cardiac vegetations of rabbits infected with VanB-type Enterococcus faecalis.
abstract: VanB-type resistance in enterococci corresponds to resistance to vancomycin but not to resistance to the related glycopeptide teicoplanin, because the vanB gene cluster is activated by the VanR(B)-VanS(B) 2-component regulatory system in response to vancomycin but not to teicoplanin. Mutations in the vanS(B) gene allow for constitutive or teicoplanin-inducible expression of the resistance genes. To analyze in vivo expression of the van genes in rabbits with experimental endocarditis, a VanB-type Enterococcus faecalis with a transcriptional fusion between the P(YB) promoter of resistance genes and the gfpmut1 gene for the green-fluorescent protein in the chromosome was constructed. Rounded heaps containing fluorescent bacteria were detected in vegetation slides from rabbits treated with vancomycin but not in those from control rabbits, revealing induction of a tightly regulated vanB gene cluster. Teicoplanin-resistant mutants were detected as fluorescent bacteria in rabbits treated with teicoplanin. Thus, the reporter system monitored expression of a glycopeptide-resistance gene in vivo at a single-cell level.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, Equipe Mixté INSERM-Université 9933, Paris, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Lefort
authors.forename: Michel
authors.initials: M
authors.lastname: Arthur
authors.forename: Florence
authors.initials: F
authors.lastname: Depardieu
authors.forename: Françoise
authors.initials: F
authors.lastname: Chau
authors.forename: Cecile
authors.initials: C
authors.lastname: Pouzet
authors.forename: Patrice
authors.initials: P
authors.lastname: Courvalin
authors.forename: Bruno
authors.initials: B
authors.lastname: Fantin
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001426:Bacterial Proteins / Q000235:genetics*; D004195:Disease Models, Animal; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004697:Endocarditis, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D005260:Female; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology; D006321:Heart / Q000382:microbiology; D011401:Promoter Regions, Genetic; D011817:Rabbits; D017334:Teicoplanin / Q000494:pharmacology / Q000627:therapeutic use*; D014640:Vancomycin / Q000494:pharmacology / Q000627:therapeutic use*; D020713:Vancomycin Resistance / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C079913:VanB protein, Enterococcus; D017334:Teicoplanin; D014640:Vancomycin