title: Sub-inhibitory concentrations of vancomycin prevent quinolone-resistance in a penicillin-resistant isolate of Streptococcus pneumoniae.
abstract: BACKGROUND
  The continuous spread of penicillin-resistant pneumococci represents a permanent threat in the treatment of pneumococcal infections, especially when strains show additional resistance to quinolones. The main objective of this study was to determine a treatment modality impeding the emergence of quinolone resistance.
  
  
  RESULTS
  Exposure of a penicillin-resistant pneumococcus to increasing concentrations of trovafloxacin or ciprofloxacin selected for mutants resistant to these drugs. In the presence of sub-inhibitory concentrations of vancomycin, development of trovafloxacin-resistance and high-level ciprofloxacin-resistance were prevented.
  
  
  CONCLUSIONS
  Considering the risk of quinolone-resistance in pneumococci, the observation might be of clinical importance.
authors.affiliation: Department of Internal Medicine, Inselspital, Freiburgstrasse, CH-3010 Berne, Switzerland. pcottagn@insel.ch
authors.forename: P
authors.initials: P
authors.lastname: Cottagnoud
authors.forename: J M
authors.initials: JM
authors.lastname: Entenza
authors.forename: M
authors.initials: M
authors.lastname: Cottagnoud
authors.forename: Y A
authors.initials: YA
authors.lastname: Que
authors.forename: P
authors.initials: P
authors.lastname: Moreillon
authors.forename: M G
authors.initials: MG
authors.lastname: Taüber
mesh_terms: D042462:4-Quinolones; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology*; D004347:Drug Interactions; D024881:Drug Resistance, Bacterial / Q000502:physiology; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance / Q000502:physiology*; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D042462:4-Quinolones; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D014640:Vancomycin