A Narrative Review of Bedaquiline and Delamanid: New Arsenals Against Multidrug-Resistant and Extensively Drug-Resistant Mycobacterium tuberculosis

Background: The treatment of multidrug-resistant (MDR-) and extensively drug-resistant tuberculosis (XDR-TB) is a formidable challenge. Treatment of MDR- and XDR-TB using bedaquiline (BDQ) and delamanid (DLM), two newly introduced medications, is steadily increasing. This narrative review aimed to present a concise overview of the existing information regarding BDQ and DLM, and elucidate their antimicrobial characteristics, resistance mechanisms, synergism with other drugs, and side effects. Methods: To collect the required information about the antimicrobial properties, a search for scientific evidence from the Scopus, PubMed, and Embase databases was performed, and all recently published articles up to May 2024 were considered. Results: BDQ had potent antimicrobial effects on various types of nontuberculous mycobacteria (NTM), including rapid-growing and slow-growing species, and MDR/XDR Mycobacterium tuberculosis. The mechanisms of BDQ resistance in M. tuberculosis primarily involve mutations in three genes: atpE, mmpR (Rv0678) and pepQ. BDQ may have synergistic effects when combined with DLM, pyrazinamide, and pretomanid/linezolid. BDQ has a low incidence of side effects. The use of BDQ may prolong the QTc interval. Similarly, DLM showed potent antimicrobial effects on NTM and MDR/XDR M. tuberculosis. The main resistance mechanisms to DLM are induced by mutations in fbiA, fbiB, fbiC, fgd1, and ddn genes. The DLM had synergistic effects with BDQ and moxifloxacin. The DLM also has few side effects in some patients including QTc prolongation. Conclusion: BDQ and DLM are suitable antibiotics with few side effects for the treatment of MDR/XDR-TB. These antibiotics have synergistic effects when combined with other antituberculosis drugs.