[Mutant prevention concentrations of fluoroquinolones for Staphylococcus aureus].
OBJECTIVE
To establish a method to measure mutant prevention concentration (MPC) in vitro, and to measure MPC of fluoroquinolones for staphylococcus aureus.


METHODS
The staphylococcus aureus strain ATCC25923 and 20 ciprofloxacin-susceptible clinical isolates were enriched in broth, and the bacterial concentrations were adjusted to 10(10) colony forming units per milliliter. The minimal inhibitory concentration (MIC), MIC for 99% of input cells (MIC99), provisional MPC (MPCpr) and MPC of moxifloxacin, gatifloxacin, pasufloxacin and ciprofloxacin for staphylococcus aureus were determined by agar plates dilution method.


RESULTS
The MPC of moxifloxacin, gatifloxacin, pasufloxacin and ciprofloxacin for staphylococcus aureus strain ATCC25923 were 0.18, 0.3, 0.75 and 1.8 microg/ml, and the MPC/MIC99 were 9.0, 7.5, 8.0 and 10.6 respectively. The MPC for 90% of the isolates (MPCpr90) of moxifloxacin, gatifloxacin, pasufloxacin and ciprofloxacin for 20 staphylococcus aureus clinical isolates were 1, 1, 4 and 8 microg/ml, and the MPCpr90/MIC90 were 8, 8, 16 and 16 respectively.


CONCLUSIONS
The capacity of moxifloxacin and gatifloxacin for restricting the selection of staphylococcus aureus resistant mutants were stronger than that of pasufloxacin and ciprofloxacin. Combined with pharmacokinetic parameters, moxifloxacin and gatifloxacin may restrict the selective enrichment of resistant mutants among ciprofloxacin-susceptible staphylococcus aureus clinical isolates, and ciprofloxacin is expected to selectively enrich mutants easily.
Cui
Jun-chang
JC
Department of Respiratory Diseases, Chinese People's Liberation Army General Hospital, Beijing 100853, China.
Liu
You-ning
YN
Wang
Rui
R
Liang
Bei-bei
BB
Pei
Fei
F
Zheng
Zhuan-jie
ZJ
D000890:Anti-Infective Agents / Q000494:pharmacology; D003470:Culture Media; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics
D000890:Anti-Infective Agents; D003470:Culture Media; D024841:Fluoroquinolones