FIG 1.
Concentration-kill curves of ciprofloxacin and moxifloxacin for exponentially growing (A) and nutrient-starved (B) 14-day-old nongrowing M. smegmatis cultures. −Cm, without chloramphenicol pretreatment, cultures were exposed to the fluoroquinolones at 1 to 100 μM for 1 day, and survival was determined via CFU enumeration; +Cm, cultures were pretreated with a sublethal (growth-inhibitory) concentration of chloramphenicol (45 μM) for 1 h to halt growth and then exposed to the fluoroquinolones. Experiments were performed three times independently in triplicate, and representative results are shown as means and standard deviations. Colored asterisks on the x axis indicate that the CFU concentration for the particular drug concentration was below the limit of detection (102 CFU/ml).