No in vitro synergistic effect of bedaquiline combined with fluoroquinolones, linezolid, and clofazimine against extensively drug-resistant tuberculosis

Purpose We explored the potential synergistic effect of bedaquiline (BDQ) combined with moxifloxacin (MFX), gatifloxacin (GAT), clofazimine (CLO), and linezolid (LZD) for treatment of extensively drug-resistant tuberculosis (XDR-TB). Methods Of 191 XDR-TB isolates, 20 exhibiting minimal inhibitory concentration (MIC) values ≥0.063 μg/mL for BDQ were selected to study potential synergistic, additive, or antagonistic drug effects using a checkerboard assay. Results Antagonism occurred in 14 (70.0%), 0 (0.0%), 13 (65.0%), and 4 (20.0%) XDR-TB isolates for BDQ-MFX, BDQ-GAT, BDQ-LZD, and BDQ-CLO combinations, respectively. Conclusion Our in vitro data demonstrate no observed synergistic effects against XDR-TB for drug combinations that included BDQ in combination with MFX, GAT, LZD, or CLO.