Minimal inhibitory concentrations of lomefloxacin and minocycline against drug-sensitive and drug-resistant isolates of M. tuberculosis compared on L-J and 7H11 media.

The in vitro activity of lomefloxacin and minocycline was tested against 46 strains of M. tuberculosis resistant to streptomycin (S), isoniazid (H) and rifampin (R) or SHR and 51 strains sensitive to SHR by the minimal inhibitory concentration (MIC) method on two different media, namely, Lowenstein-Jensen (L-J) and Middlebrook 7H11. The results of the study showed that, irrespective of the medium used, minocycline had little activity against the strains tested and the MIC was > 64 micrograms/ml. The MIC of lomefloxacin in 7H11 medium ranged from 2 to 16 micrograms/ml. There were highly significant differences in the MICs of lomefloxacin in L-J compared with 7H11. The results suggest that the activity of lomefloxacin against M. tuberculosis merits further study.