Evaluation of the mycobacterium efficacy of linezolid in vitro

Abstract

To evaluate the mycobacterium efficacy of linezolid to Mycobacterium tuberculosis bacilli and Non-tuberculous mycobacteria (NTM) in vitro, and to analyze the interaction between linezolid and other anti-TB drugs in vitro. The minimum inhibition concentrations (MICs) of 121 Mycobacterium tuberculosis clinical isolates and 30 non tuberculosis Mycobacteria isolates and the corresponding standard strains to linezolid were tested by Microplate Alamar Blue assay (MABA). The interactions between linezolid and rifampicin, isoniazid, streptomycin, ethambutol, kanamycin, ofloxacin, and rifabutin were also tested in vitro by fractional inhibitory concentration index (FICI) method. 94.2% (114/121) of the Mycobacterium tuberculosis isolates were inhibited by linezolid at concentrations ≤ 1 mg/L. There was no statistical difference in the MIC values of sensitive strains, MDR strains, and drug resistant strains other than MDR (χ(2) = 0.481, P > 0.05). Only Mycobacterium kansasii was totally sensitive to linezolid among the 5 tested NTM strains. In vitro drug combination testing displayed overall non-association between linezolid and 7 other anti-TB drugs among 8 clinical isolates and H(37) Rv. Linezolid showed great mycobacterium efficacy to Mycobacterium tuberculosis clinical isolates in vitro, regardless of the strains' drug resistant parameters. This study also showed non-association of the interactions between linezolid and 7 other anti-TB drugs in vitro.