Short-Term Regimen for TB

Sub : Sci

Sec : Health

Why in News

The introduction of shorter, all-oral regimens for tuberculosis (TB), particularly multidrug-resistant TB (MDR-TB), has been hailed as a breakthrough in TB treatment.

What is Tuberculosis:

In 2023, of the 1,75,923 global cases of MDR-TB reported to the WHO, 27% were from India.
MDR-TB arises when TB bacteria become resistant to rifampicin and isoniazid, the two most potent TB drugs, posing a 30-40% mortality risk.
Tuberculosis (TB) is an infectious airborne bacterial disease caused by Mycobacterium tuberculosis.
TB commonly affects the lungs (pulmonary TB) but can also affect other parts (extrapulmonary TB)
Tuberculosis spreads from person to person through the air, when people who are infected with TB infection cough, sneeze or otherwise transmit respiratory fluids through the air.

What is Multidrug-Resistant TB (MDR-TB):

In MDR-TB, the bacteria that cause TB develop resistance to antimicrobial drugs used to cure the disease.
MDR-TB does not respond to at least isoniazid and rifampicin, the 2 most powerful anti-TB drugs.
Treatment options for MDR-TB are limited and expensive.
CBNAAT (Cartridges Based Nucleic Acid Amplification Test) is used for early diagnosis of MDR-TB.

What is Extensively Drug-Resistant TB (XDR-TB):

XDR-TB is a form of multidrug-resistant TB with additional resistance to more anti-TB drugs.
People who are resistant to isoniazid and rifampicin, plus any fluoroquinolone and at least one of three injectable second-line drugs (amikacin, kanamycin, capreomycin) are said to have XDR-TB

Current TB Treatment Regimens:

Drug-Sensitive TB (DS-TB): Treatment involves a 6-month regimen with at least four drugs at the start. Adherence is often challenging due to the duration and side effects.
Requires 18+ months of treatment with five or more drugs, many of which have severe side effects, including hearing loss, depression, and physical discomfort.

Shorter Regimens:

Advantages:
- Reduced treatment duration (6 months for MDR-TB).
- Lower pill burden and improved adherence.
- Potentially less economic burden on patients.
- BPaL Regimen: Includes bedaquiline, pretomanid, and linezolid (BPaL/M adds moxifloxacin). Tested in the Nix-TB and ZeNix trials, the regimen showed promising results with better patient outcomes and reduced side effects when linezolid dosage was adjusted.

Critical Caveats:

Resistance to bedaquiline is a concern, necessitating close monitoring through digital tools and counselling, which are currently lacking in high-burden countries.
Linezolid can cause disabling sensory neuropathy. Alternate regimens need to be clearly defined for patient’s intolerant to the standard treatment.