title: Minocycline resistance in an oral Streptococcus infantis isolate is encoded by tet(S) on a novel small, low copy number plasmid.
abstract: We have determined the genetic basis of minocycline resistance in a strain of Streptococcus infantis isolated from a healthy human oral cavity. We demonstrate that tet(S), identical to tet(S) found on the enterococcal conjugative transposon Tn6000, is responsible for the observed resistance. The gene is located on a small, low copy number plasmid and is flanked by IS1216 elements. The tet(S) gene is capable of excising from the plasmid together with one of the IS1216 elements. The plasmid contains a putative toxin/antitoxin system related to relBE. Deletion of the toxin, relE, did not result in plasmid instability but did increase the fitness of the mutant compared to the wild-type strain.
authors.affiliation: Department of Microbial Diseases, UCL Eastman Dental Institute, University College London, London, UK.
authors.forename: Lena
authors.initials: L
authors.lastname: Ciric
authors.forename: Michael S M
authors.initials: MS
authors.lastname: Brouwer
authors.forename: Peter
authors.initials: P
authors.lastname: Mullany
authors.forename: Adam P
authors.initials: AP
authors.lastname: Roberts
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D017353:Gene Deletion; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013291:Streptococcus / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D013753:Tetracycline Resistance / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D008911:Minocycline
keywords: IS
  1216; Tn6000; relBE; toxin-antitoxin