Heteroresistance in tuberculosis: are we missing drug-resistant bacteria hiding in plain sight?
Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) remains the dominant cause of death from a bacterial infectious disease.1 Sustained global efforts to meet the ambitious elimination targets of WHO’s END-TB strategy have had a limited impact so far. This reflects the complex and multifaceted challenge posed, with multidrug resistant (MDR)-TB representing a significant and growing problem. In 2021, there were an estimated 450 000 new cases of MDR-TB, a 3.1% increase from 2020.1 Furthermore, only 36% of this population accessed treatment, due in part to the challenges of recognising drug resistance. While culture-based methods have historically provided the gold standard for drug susceptibility testing, they are limited by the prolonged turnaround time which can extend from weeks to months due to dependence on the slow growth rate of MTB. In patients with unrecognised drug-resistant TB, antituberculous therapy may therefore be ineffective or suboptimal, worsening morbidity and