Mutant prevention concentration as a measure of antibiotic potency: Studies with clinical isolates of Mycobacterium tuberculosis

The mutant prevention concentration (MPC) of a C-8-methoxy fluoroquinolone exhibited a narrow distribution for 14 genetically diverse clinical isolate s of Mycobacterium tuberculosis, indicating that results from single-isolat e studies are likely to be representative. When one isolate was challenged with a variety of antituberculosis agents, C-8-methoxy fluoroquinolones wer e exceptional in having MPCs below the maximum concentration attained in se rum by use of commonly recommended doses.