Accumulation of Norfloxacin by Mycobacterium aurum and Mycobacterium smegmatis
AUTOR(ES)
Williams, Kerstin J.
FONTE
American Society for Microbiology
RESUMO
The modified fluorescence method was used to determine the accumulation of norfloxacin by Mycobacterium aurum A+ and Mycobacterium smegmatis mc2155. By using an exogenous norfloxacin concentration of 10 μg/ml, a steady-state concentration (SSC) of 160 to 180 ng of norfloxacin/mg of cells was obtained for M. aurum, and an SSC of 120 to 140 ng of norfloxacin/mg of cells obtained for M. smegmatis. For both species of mycobacteria, the SSC was achieved within 5 min. The silicon oil method was investigated and gave higher SSCs than the modified fluorescence method. Further studies on the mechanism of norfloxacin accumulation by M. aurum were performed. An increase in the pH of the wash buffer from 7.0 to 9.0 did not significantly affect the final SSC obtained. Accumulation was nonsaturated over a norfloxacin concentration range of 0 to 100 μg/ml, and the proton motive force inhibitor 2,4-dinitrophenol (1 and 2 mM), whether it was added before or after norfloxacin was added, had no effect on the final SSC obtained. 2,4-Dinitrophenol also had no effect on norfloxacin accumulation by M. smegmatis. Furthermore, norfloxacin accumulation by M. aurum was unaffected by the presence of either Tween 80 or subinhibitory concentrations of ethambutol in the growth medium. Therefore, it is proposed that norfloxacin accumulation by mycobacteria occurs by simple, energy-independent diffusion.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=105544Documentos Relacionados
- Intracellular accumulation of norfloxacin in Mycobacterium smegmatis.
- Accumulation of Norfloxacin by Bacteroides fragilis
- Methanol production by Mycobacterium smegmatis.
- Effects of ethambutol on accumulation and secretion of trehalose mycolates and free mycolic acid in Mycobacterium smegmatis.
- Oxidative stress response and its role in sensitivity to isoniazid in mycobacteria: characterization and inducibility of ahpC by peroxides in Mycobacterium smegmatis and lack of expression in M. aurum and M. tuberculosis.
