title: TetAB46, a predicted heterodimeric ABC transporter conferring tetracycline resistance in Streptococcus australis isolated from the oral cavity.
abstract: OBJECTIVE
  To identify the genes responsible for tetracycline resistance in a strain of Streptococcus australis isolated from pooled saliva from healthy volunteers in France. S. australis is a viridans Streptococcus, originally isolated from the oral cavity of children in Australia, and subsequently reported in the lungs of cystic fibrosis patients and as a cause of invasive disease in an elderly patient.
  
  
  METHODS
  Agar containing 2 mg/L tetracycline was used for the isolation of tetracycline-resistant organisms. A genomic library in Escherichia coli was used to isolate the tetracycline resistance determinant. In-frame deletions and chromosomal repair were used to confirm function. Antibiotic susceptibility was determined by agar dilution and disc diffusion assay.
  
  
  RESULTS
  The tetracycline resistance determinant from S. australis FRStet12 was isolated from a genomic library in E. coli and DNA sequencing showed two open reading frames predicted to encode proteins with similarity to multidrug resistance-type ABC transporters. Both genes were required for tetracycline resistance (to both the naturally occurring and semi-synthetic tetracyclines) and they were designated tetAB(46).
  
  
  CONCLUSIONS
  This is the first report of a predicted ABC transporter conferring tetracycline resistance in a member of the oral microbiota.
authors.affiliation: Research Department of Microbial Diseases,  UCL Eastman Dental Institute, 256 Gray's Inn Road, University College London, London WC1X 8LD,  UK.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Warburton
authors.forename: Lena
authors.initials: L
authors.lastname: Ciric
authors.forename: Avigdor
authors.initials: A
authors.lastname: Lerner
authors.forename: Lorna A
authors.initials: LA
authors.lastname: Seville
authors.forename: Adam P
authors.initials: AP
authors.lastname: Roberts
authors.forename: Peter
authors.initials: P
authors.lastname: Mullany
authors.forename: Elaine
authors.initials: E
authors.lastname: Allan
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics*; D000328:Adult; D017920:Antiporters / Q000737:chemistry / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D009055:Mouth / Q000382:microbiology*; D011237:Predictive Value of Tests; D055503:Protein Multimerization / Q000235:genetics*; D012471:Salivary Proteins and Peptides / Q000737:chemistry / Q000235:genetics; D013291:Streptococcus / Q000235:genetics* / Q000302:isolation & purification; D013753:Tetracycline Resistance / Q000235:genetics*
chemical_list: D018528:ATP-Binding Cassette Transporters; D017920:Antiporters; D001426:Bacterial Proteins; D012471:Salivary Proteins and Peptides; C079051:tetA protein, Bacteria