Evaluation of the antibacterial effect in vitro of moxifloxacin and linezolid on nontuberculous mycobacterium

Objective: To evaluate the antibacterial effect in vitro of moxifloxacin and linezolid on nontuberculous mycobacterium (NTM), and provide scientific evidence for treatment of NTM disease. Materials and methods: From January 2012 to June 2014, a total of 98 NTM strains were collected from suspected tuberculosis patients (n=98) in our hospital. The minimal inhibitory concentration (MIC) of the moxifloxacin and linezolid against NTM isolates were detected by microdilution broth method. Results: The sensitivity of moxifloxacin to Mycobacterium avium complex was 84.5% (49/58), which was significantly higher than that of Mycobacterium abscess (11.5%, 3/26) (χ2=40.505, P=0.000). The sensitivity of linezolid to Mycobacterium avium complex was 65.5% (38/58), which was lower than that 88.5% (23/26) of Mycobacterium abscess. The difference was statistically significant (χ2=4.753, P=0.029). Among Mycobacterium avium complex, the sensitivity of Moxifloxacin to Mycobacterium avium (96.2%, 25/26) was higher than that of Mycobacterium intracellulare (75%, 24/32), the difference was statistically significant (Fisher test, P=0.033); The sensitivity of linezolid to Mycobacterium avium and Mycobacterium intracellulare were 69.2% (18/26) and 62.5% (20/32) respectively. There was no significant difference between the two groups (χ2=0.288, P=0.592). Conclusion: Different species of NTM differed in the drug susceptibility profiles. It is necessary to identify and perform drug sensitivity test in the diagnosis and treatment of NTM diseases.