Are We Slipping Back on Tuberculosis Control?

Across Europe, tuberculosis (TB) is causing renewed concern, particularly the extensively drug-resistant form (XDR-TB), which is proving as deadly as in the pre-antibiotic era. A large retrospective study published in The Lancet found that treatment failed in 60% of XDR-TB cases.

“These results are extremely concerning, as a pooled 40% success rate is comparable to the rate of spontaneous cure for tuberculosis from the pre-antibiotic era,” the study authors wrote. In 2021, the World Health Organization (WHO) updated its definition of XDR-TB. The new definition of pre-XDR-TB is TB caused by Mycobacterium tuberculosis strains that fulfill the definition of multidrug-resistant and rifampicin-resistant TB (MDR/RR-TB) and are also resistant to any fluoroquinolone and at least one Group A drug.

Group A drugs, considered the most potent in the second-line classification for treating drug-resistant TB using longer regimens, include levofloxacin, moxifloxacin, bedaquiline, and linezolid. The retrospective analysis included 11,003 patients diagnosed with MDR/RR-TB between 2017 and 2023 across the WHO European region. Of these, 48.4%, 34.0%, and 17.6% were resistant to bedaquiline, linezolid, and both, respectively.

Among 156 patients with known outcomes, 40.2% achieved treatment success (95% CI 28.4%-53.2%), while treatment failed in 37.1% (26.1%-49.7%), and 21.3% (15.7%-28.2%) died. Failure was more likely when fewer effective antibiotics were used; each additional active drug reduced the risk for failure by 35%. Patients treated in upper- to middle-income countries had a nearly 14 times higher risk for failure than those in high-income countries.

“On average, half of the drugs that patients with extensively drug-resistant tuberculosis received were ineffective according to drug susceptibility testing. Findings of this study underscore the urgent need for access to rapid drug-susceptibility testing for all drugs in use and effective treatment regimens, including new compounds, for all patients affected by extensively drug-resistant tuberculosis,” the authors emphasized. Therefore, the prevention of further drug resistance is critical, and treatment must rely on drugs with proven susceptibility, ensuring accessibility in all clinical settings.

The study authors urged the rapid implementation of effective antibiotic stewardship programs tailored to drug-resistant TB. “Global coalition and equitable resource distribution are critical to advancing the fight against drug-resistant tuberculosis and achieving the goals of the WHO End TB strategy,” the authors concluded.

This story was translated from Univadis Italy.

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