Treatment Outcomes of Fluoroquinolone-Resistant Multidrug-Resistant Tuberculosis: An Implication for Delamanid

We greatly appreciated a study by Choi et al. [1] reporting treatment outcomes in pre-extensively drug-resistant tuberculosis (pre-XDR-TB) patients (fluoroquinolone resistance) with propensity score matching. The data of pre-XDR-TB patients were collected retrospectively over 7 years [1]. Drug-resistant tuberculosis (DR-TB) is one of the most infectious diseases, with a low rate of treatment success and high mortality rates. It was proposed that the treatment success rate of pre-XDR TB was lower than that of rifampicin-resistant or multidrug-resistant tuberculosis (MDR-TB) [2]. Patients with pre-XDR have limited therapeutic options. The use of second-line injectable drugs (SLIDs), such as kanamycin and capreomycin, was significantly associated with treatment failure; therefore, the World Health Organization (WHO) announced the use of all oral regimens to treat DR-TB patients, either for shorter or longer regimens. Since SLIDs were no longer used to treat DR-TB patients, in 2021, the WHO revised the definition of pre-XDR TB to a case of MDR-TB with additional resistance to any fluoroquinolone (levofloxacin or moxifloxacin) [3]. Those who were previously treated with antitubercular drugs and with lung cavities were risk factors for pre-XDR TB and XDR-TB [4]. As reported by Choi et al. [1], more than 60% of DR-TB patients had a history of TB treatment.