Emergence of fluoroquinolone resistance in Mycobacterium tuberculosis during continuously dosed moxifloxacin monotherapy in a mouse model.

Fluoroquinolone resistance in tuberculosis may rapidly emerge. Mice infected with high titers of aerosolized Mycobacterium tuberculosis and treated for 8 weeks with four concentrations of moxifloxacin (0.125, 0.

The Mycobacterium tuberculosis SigD sigma factor controls the expression of ribosome-associated gene products in stationary phase and is required for full virulence.

During infection Mycobacterium tuberculosis is exposed to several environmental conditions depending on the stage and severity of the disease. To survive, M. tuberculosis uses alternate sigma factors to regulate its gene expression in response to the changing host environment.

Regulation of autolysins in teichuronic acid-containing Bacillus subtilis cells.

Bacillus subtilis cells grown under phosphate starvation induce teichuronic acid (TUA) synthesis while simultaneously repressing teichoic acid synthesis (TA). The turnover rates of TA-containing and TUA-containing walls are similar, indicating that autolysin function is similar and suggesting that modulation of autolytic function may be similar. In this study, it is demonstrated, utilizing fluorescein isothiocyanate (FITC)-dextran to probe the wall pH, that a low pH exists in the wall matrix.

Evidence that the cell wall of Bacillus subtilis is protonated during respiration.

Several independent experiments suggest that cell walls of Bacillus subtilis are protonated during growth. When cells were grown in the presence of fluorescein-labeled dextran to saturate the cell walls, centrifuged, and suspended in PBS, fluorescence-activated cell sorter analyses revealed the bacteria were only poorly fluorescent. In contrast, when the bacteria were purged with N(2) to dissipate protonmotive force (pmf) fluorescence became intense.