In vitro Susceptibilities of Linezolid and Tigecycline against Drug-Resistant Mycobacterium tuberculosis Isolates

Objective: The treatment of multidrug-resistant tuberculosis (MDR-TB) is extremely difficult, and there is a need for new and effective drugs. The aim of this study was to determine the minimum inhibitory concentration (MIC) of linezolid (LZD) and tigecycline (TGC) against DR Mycobacterium tuberculosis isolates. Materials and Methods: The study was conducted at a referral chest diseases and chest surgery hospital. Isolates were obtained from consecutive patients. Susceptibilities to LZD and TGC were studied using the agar dilution method. Results: A total of 26 strains resistant to any drug against M. tuberculosis were tested. Ten isolates (38.5%) had an MDR pattern. MIC50 and MIC90 values of LZD were detected to be 0.05 and 1 mu g/mL, respectively. Among all isolates, 96% M. tuberculosis strains were found to be susceptible to LZD. An approved breakpoint for TGC does not exist. MIC50 and MIC90 values of TGC were found to be 16 and 64 mu g/mL, respectively. Conclusion: LZD seems to be a good alternative for treatment of DR-TB. However, TGC showed high MIC values. Treatment of DR-TB with TGC is not promising according to study results.