Drug-resistant tuberculosis
Also called: MDR-TB, XDR-TB, DR-TB · Topic: Human Capital: Education, Health and Demographic Dividend · NCERT: Beyond NCERT
Meaning
Drug-resistant tuberculosis (DR-TB) is TB caused by bacteria that the usual medicines can no longer kill. The two main forms are MDR-TB and XDR-TB.
- MDR-TB (multidrug-resistant TB) resists at least isoniazid and rifampicin, the two strongest first-line drugs. These are the standard medicines given to every new patient first.
- XDR-TB (extensively drug-resistant TB) is MDR-TB that also resists some of the stronger back-up medicines. It is much harder to cure.
Resistance often grows when a patient stops treatment early or gets the wrong medicines. A resistant patient can then pass that resistant TB on to others. Treatment is longer, more toxic (harsher on the body) and costs more, so India and WHO report it separately from ordinary TB.
Example
Suppose a patient in India stops their TB tablets midway because they feel better. Their surviving bacteria can become resistant. When they fall ill again, a NAAT test checks the bacteria's genetic material. NAAT is a fast molecular test that can also show resistance to rifampicin. If the test confirms MDR-TB, the patient moves to a longer course with second-line drugs.
Don't confuse with
- Drug-susceptible TB: the standard first-line medicines still kill this TB. India's headline TB "treatment success rate" counts only these patients, so it does not tell you how well drug-resistant cases are being cured.