Updates on diagnostics and new treatment guidelines for TB

The WHO held an expert consultation on the definition of extensively drug-resistant tuberculosis on 27-29 October 2020, the outcomes can be summarized as follows:

Unchanged definitions

• Rifampicin-resistant TB: TB caused by M. tuberculosis resistant to rifampicin
• Multidrug-resistant tuberculosis (MDR-TB): TB caused by Mycobacterium tuberculosis (M. tuberculosis) resistant to at least isoniazid and rifampicin

Updated definitions as of January 2021

• Pre-XDR-TB: TB caused by M. tuberculosis strains that fulfil the definition of MDR/RR-TB and that are also resistant to any fluoroquinolonea
• XDR-TB: TB caused by M. tuberculosis strains that fulfil the definition of MDR/RR-TB and that are also resistant to any fluoroquinolonea and at least one additional Group A drug^b

1. The fluoroquinolones include levofloxacin and moxifloxacin, because these are the fluoroquinolones currently recommended by WHO for inclusion in shorter and longer regimens.
2. The Group A drugs are currently levofloxacin or moxifloxacin, bedaquiline and linezolid; therefore, XDR-TB is MDR/RR-TB that is resistant to a fluoroquinolone and either bedaquiline or linezolid (or both). The Group A drugs may change in the future; therefore, the terminology “Group A” is appropriate here and will apply to any Group A drugs in the future.

Source: WHO

The WHO has also issued updated diagnostic and treatment guidelines for tuberculosis this year. In this video Professor David Moore from the London School of Hygiene & Tropical Medicine and Director of the TB Centre at the School presents a summary of the updated guidelines and discusses their implications for the detection and management of TB cases, especially for high burden countries.