FIG 2.

ROS mitigation reduces moxifloxacin-mediated killing of M. tuberculosis. (A) Plan for detecting thiourea (TU) and bipyridyl (BP) effects on moxifloxacin lethality. (B) Exponentially growing M. tuberculosis H37Rv cultures were either left untreated or treated with 10 mM TU for 1 h before addition of the indicated concentrations of moxifloxacin (MOXI; 1× MIC = 0.5 μM) for 10 days followed by determination of CFU. (C) Effect of bipyridyl. M. tuberculosis as for panel B was untreated or treated with 250 μM BP for 15 min prior to addition moxifloxacin as for panel B. (D) The Mrx1-roGFP2 biosensor ratiometric response was determined after 48 h treatment of M. tuberculosis cultures with the indicated concentrations of MOXI alone or with 250 μM BP. (E) M. tuberculosis cultures were treated with moxifloxacin, the drug was removed by washing, and cells were plated on drug-free 7H11 agar with or without catalase followed by CFU determination. (F) M. tuberculosis cultures were treated with 1× MIC of moxifloxacin for the indicated times, washed, and plated with or without catalase (17.5 U/mL of agar). Percentage survival was calculated relative to CFU of cultures at 0 h. Statistical significance was calculated between the drug-alone group and the drug + catalase group. Statistical considerations were as in Fig. 1.