Multidrug Resistant TB (MDR-TB)
This is a dangerous form of TB that does not respond to at least isoniazid and rifampicin, the two most powerful anti-TB drugs. India has the highest MDR-TB rates in the world.
The reasons for emersion are mismanagement of TB treatment and person-to-person transmission
Treatment options are limited and expensive, recommended medicines are not always available, and patients experience many adverse effects from the drugs. Duration of treatment is as high as 18 to 24 months.
In some cases even more severe drug-resistant TB may develop.Extensively drug-resistant TB, XDR-TB, is a form of multidrug-resistant TB with additional resistance to more anti-TB drugs that therefore responds to even fewer available medicines.
Drug resistance can be detected using special laboratory tests which test the bacteria for sensitivity to the drugs or detect resistance patterns.
These tests can be molecular in type (eg, Xpert MTB/RIF) or else culture-based. Molecular techniques can provide results within hours and have been successfully implemented even in low resource settings.
Solutions to control drug-resistant TB are to:
- provide access to diagnosis;
- ensure adequate infection control in facilities where patients are treated;
- ensure the appropriate use of recommended second-line drugs.
In 2014, an estimated 480 000 people worldwide developed MDR-TB. It is estimated that about 9.7% of these cases were XDR-TB
Some of the 2nd line drugs used include: injectable kanamycin, moxifloxacin, PAS, ethionamide, cycloserine, and clofazimine.
Newer drugs like Bedaquiline and new diagnostic tests are emerging.