A Bedaquiline, Pyrazinamide, Levofloxacin, Linezolid, and Clofazimine Second-line Regimen for Tuberculosis Displays Similar Early Bactericidal Activity as the Standard Rifampin-Based First-line Regimen

Background In 2018 the World Health Organization recommended a switch to an all oral bedaquiline-based second-line regimen for treatment of drug-resistant tuberculosis (DR-TB). How these new second-line regimens fare in comparison to first-line regimens for treatment of drug-sensitive tuberculosis (DS-TB) is not well known. Methods In this study, we contemporaneously enrolled subjects with DS-TB (n = 31) or DR-TB (n = 23) and assessed their response to therapy with first-line (rifampin, isoniazid, ethambutol, pyrazinamide) or second-line (bedaquiline, pyrazinamide, levofloxacin, linezolid, clofazimine) regimens, respectively. Results We found that the early bactericidal activity of first- and second-line regimens was similar during the first 2 weeks of therapy as determined by BACTEC MGIT, colony-forming units, and a liquid limiting dilution assay capable of detecting differentially detectable/culturable Mycobacterium tuberculosis. Furthermore, an identical percentage (77.8%) of subjects from the DS-TB and DR-TB cohorts converted to culture negative after 2 months of therapy. Conclusions Despite presenting with more advanced disease at time of treatment, subjects with DR-TB receiving an all oral bedaquiline-based second-line treatment regimen displayed a similar microbiological response to therapy as subjects with DS-TB receiving a first-line treatment regimen.