Mechanisms of action and therapeutic efficacies of the lipophilic antimycobacterial agents clofazimine and bedaquiline.

Drug-resistant (DR)-TB is the major challenge confronting the global TB control programme, necessitating treatment with second-line anti-TB drugs, often with limited therapeutic efficacy. This scenario has resulted in the inclusion of Group 5 antibiotics in various therapeutic regimens, two of which promise to impact significantly on the outcome of the therapy of DR-TB. These are the 're-purposed' riminophenazine, clofazimine, and the recently approved diarylquinoline, bedaquiline.

Effects of clofazimine on planktonic and biofilm growth of Mycobacterium tuberculosis and Mycobacterium smegmatis.

Mycobacteria form lipid-rich biofilms that restrict the efficacy of antimicrobial chemotherapy, possibly necessitating the use of lipophilic antibiotics. In the current study, the activity of one such agent, clofazimine, against Mycobacterium tuberculosis and Mycobacterium smegmatis planktonic cells and biofilms was investigated. Minimum inhibitory concentrations (MICs) of clofazimine were determined for planktonic cultures, whilst minimum bactericidal concentrations (MBCs) were determined for planktonic, biofilm-producing and biofilm-encased organisms using standard bacteriological procedures.