Evidence for active drug efflux in fluoroquinolone resistance in Clostridium hathewayi.
BACKGROUND
Most fluoroquinolones have shown limited effectiveness against anaerobic bacteria. Evidence for a multidrug efflux pump, like those involved in fluoroquinolone resistance in some other bacteria, was investigated in Clostridium hathewayi.


METHODS
A parent strain of C.hathewayi was isolated from human intestinal microflora on a medium with a low concentration of norfloxacin and a mutant strain was selected from it on a medium with a high concentration of norfloxacin. Fluoroquinolone sensitivity, drug accumulation, and the effects of different concentrations of fluoroquinolones on the kinetics of growth in the presence and absence of efflux pump inhibitors were measured.


RESULTS
Both strains were resistant to several fluoroquinolones and dyes. The pump inhibitor reserpine increased the sensitivity of both strains to some drugs; it affected the growth kinetics and the efflux of norfloxacin and ethidium bromide.


CONCLUSIONS
The efflux of fluoroquinolone appears to be one reason for fluoroquinolone resistance inC. hathewayi.
Rafii
Fatemeh
F
Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079, USA. frafiI@nctr.fda.gov
Park
Miseon
M
Wynne
Rebecca
R
D000890:Anti-Infective Agents / Q000493:pharmacokinetics / Q000494:pharmacology; D003013:Clostridium / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D024881:Drug Resistance, Bacterial; D024841:Fluoroquinolones / Q000493:pharmacokinetics* / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D026901:Membrane Transport Proteins; D009643:Norfloxacin / Q000493:pharmacokinetics / Q000494:pharmacology
D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D026901:Membrane Transport Proteins; D009643:Norfloxacin