FIG. 2.

Azithromycin and gentamicin growth curves. NTHi strain 2019 expressing GFP was grown with various concentrations of azithromycin (A) and gentamicin (B) as indicated. The azithromycin (0.125 μg/ml) and gentamicin (0.25 μg/ml) concentrations (black circles) were chosen for further studies, because these were the highest concentrations of antibiotic in which the growth reached near that of the nonantibiotic control over time (24-h time point). Both of these concentrations caused delayed growth, with gentamicin being more profoundly altered.