Superior efficacy of a bedaquiline, delamanid and linezolid combination regimen in a mouse-TB model.

BACKGROUND The treatment success rate of drug-resistant tuberculosis (DR-TB) is alarmingly low. Therefore, more effective and less complex regimens are urgently required. METHODS We compared the efficacy of an all oral DR-TB drug regimen consisting of bedaquiline (25 mg/kg), delamanid (2.5 mg/kg) and linezolid (100 mg/kg) (BDL) on the mycobacterial load in the lungs and spleen of TB infected mice during a treatment period of 24 weeks. This treatment was compared to the standard regimen of isoniazid, rifampicin, pyrazinamide and ethambutol (HRZE). Relapse was assessed 12 weeks post-treatment. Two logistic regression models were developed to compare the efficacy of both regimens. RESULTS Culture negativity in the lungs was achieved at 8 and 20 weeks of treatment with BDL and HRZE, respectively. After 14 weeks of treatment only one mouse relapsed in the BDL group, while in the HRZE group relapse was still observed at 24 weeks of treatment. Predictions from the final mathematical models showed that a 95% cure rate was reached after 20.5 and 28.5 weeks of treatment with BDL and HRZE, respectively. CONCLUSION The BDL regimen was observed to be more effective than HRZE and could be a valuable option for the treatment of DR-TB.