Sub-inhibitory concentrations of vancomycin prevent quinolone-resistance in a penicillin-resistant isolate of Streptococcus pneumoniae.
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.
Cottagnoud
P
P
Department of Internal Medicine, Inselspital, Freiburgstrasse, CH-3010 Berne, Switzerland. pcottagn@insel.ch
Entenza
J M
JM
Cottagnoud
M
M
Que
Y A
YA
Moreillon
P
P
Taüber
M G
MG
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*
D042462:4-Quinolones; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D014640:Vancomycin