Risk factors for baseline bedaquiline (BDQ) resistance, amplification during treatment, and correlations with treatment outcomes are not fully understood. This cohort included Armenian patients with multidrug-resistant TB predominantly fluoroquinolone-resistant enrolled between 2013 and 2015 in a BDQ compassionate use program. BDQ resistance at baseline and during treatment was assessed using MGIT (pDSTMGIT), minimal inhibitory concentration in 7H11 (MIC7H11), and whole-genome sequencing. Risk factors, such as treatment effectiveness or stage of the disease, were analyzed for association with baseline BDQ resistance, acquired BDQ resistance, and treatment outcome. Among 39 patients, baseline BDQ resistance was 6% (2/33) by pDSTMGIT and 7% (2/29) by MIC7H11. All four baseline isolates with an Rv0678 mutation were phenotypically resistant. During treatment, 48% of the patients acquired BDQ resistance by pDSTMGIT, and 52% acquired mutations at various frequencies (97% in Rv0678). None of the factors significantly contributed to baseline or acquired BDQ resistance. Unfavorable treatment outcome (41%) was more frequent in the presence of acquired Rv0678 mutations [odds ratio (OR) 132, 95% confidence interval (CI) 7.43, 2375], phenotypic BDQ resistance (OR 176, 95% CI 6.48, 2423), or MIC increase above or below the critical concentration (both OR 84.3, 95% CI 2.93, 2423) during treatment. For these highly treatment-experienced patients, low baseline prevalence but high incidence of acquired BDQ resistance was observed. Acquisition of mutations in BDQ candidate resistance genes, regardless of their frequency, or increased MICs during treatment, even below the critical concentration, should be seen as a warning sign of resistance amplification and increased risk of unfavorable treatment outcome.

Each day more than 500 children younger than 15 years die from tuberculosis. Considerable progress has been made to control tuberculosis, but the impact on reducing the burden of childhood tuberculosis lags behind that in adults. A key barrier to decreasing morbidity and mortality associated with childhood tuberculosis is the paucity of accurate and feasible diagnostic tools for this population. WHO estimates that 58% of children younger than 5 years with tuberculosis are never diagnosed or reported.

BACKGROUND

Bedaquiline (BDQ) resistance presents a critical challenge in the fight against tuberculosis (TB), particularly multidrug-resistant (MDR) strains. The emergence of resistance to BDQ, a key drug in treating MDR-TB, poses significant threats to TB treatment effectiveness.

METHODS

The National Institute of Tuberculosis and Respiratory Diseases in Delhi and the Médecins Sans Frontières clinic in Mumbai provide BDQ, delamanid, and carbapenem-based regimens for patients with suspected or confirmed treatment failure. BDQ phenotypic drug-susceptibility testing (DST) was performed for all BDQ-exposed patients. Treatment regimens were individualized based on exposure history, comorbidities, drug interactions, prior adverse drug reactions, and DST results.

RESULTS

Of 117 BDQ-exposed patients from December 2020–December 2022, 42 (36%) exhibited a BDQ-resistant strain. Median (IQR) age was 24 (22–32) years, with 63 (54%) females and 94% with pulmonary TB. Patients with a BDQ-resistant strain were older (median age: 27 vs 23 years; P = .04), more likely to have lung cavities (risk ratio [RR]: 1.8; 95%-CI: 1.1–3.1; P = .02), and be resistant to clofazimine (RR: 2.3; 95%-CI: 1.5–3.6; P = .001). Overall, 102 patients initiated treatment. Patients with BDQ-resistance had higher risk of unfavorable outcomes compared with BDQ-susceptible patients (RR:2.1; 95%-CI: 1.5–2.8; P < .001). Overall, 87% (33/38) of patients with BDQ-resistance experienced unfavorable treatment outcomes: 15 (40%) died, 15 (40%) had treatment failure, and 3 (8%) were lost-to-follow-up.

CONCLUSIONS

The study highlights a concerning rate of BDQ-resistance among previously treated patients, resulting in poor treatment outcomes. To prevent treatment failure, we recommend implementing BDQ-DST, developing affordable and accurate rapid tests for BDQ-resistance, and intensifying research and development efforts for newer TB drugs.

Pretomanid is a key anti-TB drug included in the WHO list of essential medications. The current EMA-approved label for pretomanid restricts its use to the regimen comprising bedaquiline, pretomanid and linezolid (BPaL) and only for extensively drug-resistant-TB or multidrug-resistant TB, "when antibiotics used for the latter form of TB do not work or cause unacceptable side effects." This restricted use implies that the older, prolonged and poorly tolerated regimens remain the recommended treatment for most cases of drug-resistant TB. The authors, representing many respiratory groups and societies, call for the label expansion of pretomanid to align with global guidelines, allowing for broader use.

BACKGROUND

Only 63% of patients initiating multidrug-resistant/rifampicin-resistant tuberculosis (MDR/RR-TB) treatment in 2020 were treated successfully. 24-Week all-oral bedaquiline, pretomanid, and linezolid (BPaL)–based regimens have demonstrated higher rates of treatment success and have been recommended by the World Health Organization. Operational research is urgently required to evaluate these regimens in non-trial settings.

METHODS

This was a prospective cohort study of patients with microbiologically confirmed MDR/RR-TB and pre–extensively drug-resistant TB (pre-XDR-TB) initiated on BPaL-based regimens in Belarus and Uzbekistan (February 2022–June 2023). All clinical care and research procedures were delivered by treating physicians. After treatment completion, patients were followed up at 6 and 12 months, including collecting sputum to ascertain recurrence. The primary objective was to estimate the effectiveness (cured or treatment completed) and safety (the occurrence of serious adverse events) of BPaL-based regimens.

RESULTS

A total of 677 patients initiated treatment with BPaL-based regimens during the study. We documented successful treatment outcomes in 95.3% (427/448) of patients with MDR/RR-TB treated with BPaL plus moxifloxacin and 90.4% (207/229) of patients with pre–XDR-TB treated with BPaL plus clofazimine. 10.2% (69/677) experienced serious adverse events including 24 deaths (3.5%), 11 of which occurred during treatment. 83.3% (20/24) of deaths were not related to TB or TB treatment. Of patients who were successfully treated and completed 12-month follow-up, 0.5% (2/383) had recurrence.

CONCLUSIONS

BPaL-based regimens for MDR/RR-TB and pre–XDR-TB are safe and highly effective in non-trial settings. These regimens should be considered for widespread implementation globally, and further research is needed to evaluate their performance in other key populations.

BACKGROUND

There are few data on the treatment of children and adolescents with multidrug-resistant (MDR) or rifampicin-resistant (RR) tuberculosis, especially with more recently available drugs and regimens. We aimed to describe the clinical and treatment characteristics and their associations with treatment outcomes in this susceptible population.

METHODS

We conducted a systematic review and individual participant data meta-analysis. Databases were searched from Oct 1, 2014, to March 30, 2020. To be eligible, studies must have included more than five children or adolescents (0-19 years of age) treated for microbiologically confirmed or clinically diagnosed MDR or RR tuberculosis within a defined treatment cohort, and reported on regimen composition and treatment outcomes. Abstracts were screened independently by two authors to identify potentially eligible records. Full texts were reviewed by two authors independently to identify studies meeting the eligiblity criteria. For studies meeting eligiblity criteria, anonymised individual patient data was requested and individiual level data included for analysis. The main outcome assessed was treatment outcome defined as treatment success (cure or treatment completed) versus unfavourable outcome (treatment failure or death). Multivariable logistic regression models were used to identify associations between clinical and treatment factors and treatment outcomes. This study is registered with Prospero (CRD42020187230).

FINDINGS

1417 studies were identified through database searching. After removing duplicates and screening for eligibility, the search identified 23 369 individual participants from 42 studies, mostly from India and South Africa. Overall, 16 825 (72·0%) were successfully treated (treatment completed or cured), 2848 died (12·2%), 722 (3·1%) had treatment failure, and 2974 (12·7%) were lost to follow-up. In primary analyses, the median age was 16 (IQR 13-18) years. Of the 17 764 (87·1%) participants with reported HIV status, 2448 (13·8%) were living with HIV. 17 707 (89·6%) had microbiologically confirmed tuberculosis. After adjusting for significant factors associated with treatment outcome, the use of two (adjusted odds ratio [OR] 1·41 [95% CI 1·09-1·82]; p=0·008) or three (2·12 [1·61-2·79]; p<0·0001) WHO-classified group A drugs (bedaquiline, moxifloxacin, levofloxacin, and linezolid) compared with the use of no group A drugs at all was positively associated with treatment success.

INTERPRETATION

Younger and clinically diagnosed children are underrepresented among those treated for MDR and RR tuberculosis and should be a focus for case-finding efforts. Overall treatment outcomes in our analysis were better than in adults but lower than the international targets of 90% or more individuals successfully treated. Treatment with more group A drugs was associated with better treatment outcomes in children and adolescents, highlighting the need for more rapid access to these drugs and improved regimens.