Rolling out new anti-tuberculosis drugs without diagnostic capacity

Strategies to Enhance Diagnostic Capabilities for the New Drug-Resistant Tuberculosis (DR-TB) Drugs

The global burden of drug-resistant tuberculosis (DR-TB) continues to challenge healthcare systems worldwide. There is a critical need to tackle DR-TB by enhancing diagnostics and drug susceptibility testing (DST) capabilities, particularly for emerging DR-TB drugs. This endeavor is crucial to optimize the efficacy of new therapeutic regimens and prevent the resistance and overuse of these invaluable weapons. Despite this urgency, there remains a lack of comprehensive review of public health measures aimed at improving the diagnostics and DST capabilities. In this review, we outline strategies to enhance the capabilities, especially tailored to address the challenges posed by resistance to new DR-TB drugs. We discuss the current landscape of DR-TB drugs, existing diagnostic and susceptibility testing methods, and notable gaps and challenges in these methods and explore strategies for ensuring fair access to DST while narrowing these disparities. The strategies include public health interventions aimed at strengthening laboratory infrastructure, workforce training, and quality assurance programs, technology transfer initiatives, involving drug developers in the DST development, establishing national or regional referral hubs, fostering collaboration and resources pooling with other infection control efforts, extending testing access in underserved areas through public-private partnerships, advocating for lowering costs or loans at low interest, remote technical support, and implementing mandatory molecular surveillance monitoring. This review underscores the urgent need to enhance DST capacities for new DR-TB drugs and identifies opportunities for innovation and improvement. Assessing the extent of the global health impact of these measures is crucial to ensure their effectiveness in combating DR-TB.

Refined understanding of the impact of the Mycobacterium tuberculosis complex diversity on the intrinsic susceptibility to pretomanid

Previous work reported unprecedented differences in the intrinsic in vitro susceptibility of the Mycobacterium tuberculosis complex (MTBC) to pretomanid (Pa) using the Mycobacteria Growth Indicator Tube (MGIT) system. We tested 125 phylogenetically diverse strains from all known MTBC lineages (1-9) without known Pa resistance mutations and four strains with known resistance mutations as controls. This confirmed that MTBC, unlike most bacteria-antimicrobial combinations, displayed substantial differences in the intrinsic susceptibility relative to the technical variation of Pa MIC testing. This was also the case for the Middlebrook 7H11 (7H11) medium, demonstrating that these differences were not specific to MGIT. Notably, lineage 1 was confirmed to have intrinsically elevated MICs compared with lineages 2, 3, 4, and 7 (L2-4/7), underlining the urgent need for WHO to publish its decision of whether lineage 1 should be deemed treatable by BPaL(M), the now preferred all-oral regimen for treating rifampin-resistant tuberculosis. Lineages 5 and 6, which are most frequent in West Africa, responded differently to Pa, with lineage 5 being more similar to L2-4/7 and lineage 6 being more susceptible. More data are needed to determine whether 7H11 MICs are systematically lower than those in MGIT.

IMPORTANCE

This study confirmed that the Mycobacterium tuberculosis complex lineage 1, responsible for 28% of global tuberculosis cases, is less susceptible to pretomanid (Pa). It also refined the understanding of the intrinsic susceptibilities of lineages 5 and 6, most frequent in West Africa, and lineages 8 and 9. Regulators must review whether these in vitro differences affect the clinical efficacy of the WHO-recommended BPaL(M) regimen and set breakpoints for antimicrobial susceptibility testing accordingly. Notably, regulators should provide detailed justifications for their decisions to facilitate public scrutiny.

Recent Biochemical Advances in Antitubercular Drugs: Challenges and Future

Tuberculosis (TB) is one of the leading causes of death world-wide after AIDS. It infects around one-third of global population and approximately two million people die annually from this disease because it is a very contagious disease spread by Mycobacterium tuberculosis. The increasing number of drug-resistant strains and the failure of conventional treatments against this strain are the challenges of the coming decades. New therapeutic techniques aim to confirm cure without deterioration, to reduce deaths, contagions and the formation of drug-resistant strains. A plethora of new diagnostic tests are available to diagnose the active tuberculosis, screen latent M. tuberculosis infection, and to identify drug-resistant strains of M. tuberculosis. When effective prevention strategies do not prevail, high rates of early case detection and successive cures to control TB emergence would not be possible. In this review, we discussed the structural features of M. tuberculosis, Multi drug resistance tuberculosis (MDR-TB), extremely drug-resistant tuberculosis (XDR-TB), the mechanism of M. tuberculosis infection, the mode of action of first and second-line antitubercular drugs, the mechanism of resistance to the existing drugs, compounds in preclinical and clinical trial and drugs presently available for the treatment of tuberculosis. Moreover, the new diagnostic techniques to detect M. tuberculosis are also discussed in this review.