Key Questions Answered
Q1. What is drug-resistant TB?
Answer: Drug-resistant TB (DR-TB) occurs when the TB bacteria are resistant to one or more anti-TB medicines. Two important forms are rifampicin-resistant TB (RR-TB) and multidrug-resistant TB (MDR-TB), in which the bacteria are resistant to at least rifampicin and isoniazid. More extensive resistance is classified as pre-XDR-TB or XDR-TB according to the current WHO definitions.
Q2. Is drug-resistant TB a major problem in India?
Answer: Yes. India carries the largest share of the global MDR/RR-TB burden. According to the WHO Global Tuberculosis Report 2025, an estimated 390,000 people developed MDR/RR-TB globally in 2024, and India accounted for approximately 32% of these cases. This translates to roughly 1.25 lakh estimated incident MDR/RR-TB cases in India in 2024. This is an estimated burden and should not be confused with the number of patients actually diagnosed or notified.
Q3. Does incomplete TB treatment cause drug resistance?
Answer: Incomplete or inappropriate treatment can contribute to the development of drug resistance, particularly when effective drugs are not taken in the correct combination or treatment is interrupted. However, it is important to understand that not every patient with drug-resistant TB developed resistance because of incomplete treatment. A person can also acquire drug-resistant TB through transmission from someone who already has resistant TB. WHO identifies both treatment mismanagement and person-to-person transmission as important drivers of MDR/RR-TB.
Q4. How can resistance develop during treatment?
Answer: If TB bacteria are exposed to an inadequate or inappropriate drug regimen, susceptible bacteria may be killed while resistant bacteria survive and multiply. This can result in treatment failure and emergence or amplification of drug resistance.
Therefore, patients should never stop, add, remove or change TB medicines on their own.
Q5. Can someone who has never taken TB treatment have drug-resistant TB?
Answer: Yes. This is an important point that is sometimes misunderstood. A person who has never received TB treatment can acquire a drug-resistant strain from another person with drug-resistant TB. Therefore, drug resistance is not always the result of previous treatment.
Q6. How do we detect drug resistance?
Answer: Rapid molecular tests can identify TB and detect important drug resistance much earlier than waiting for conventional culture-based results. Tests such as CBNAAT and Truenat can detect rifampicin resistance, while additional molecular or phenotypic drug-susceptibility testing may be required to identify resistance to other medicines.
India has substantially expanded rapid molecular testing. WHO reports that in 2024, India was among the high MDR/RR-TB burden countries achieving at least 80% coverage of rifampicin-resistance testing among people diagnosed with bacteriologically confirmed pulmonary TB.
Q7. What are MDR-TB, pre-XDR-TB and XDR-TB?
Answer: MDR-TB means resistance to at least rifampicin and isoniazid.
Pre-XDR-TB means MDR/RR-TB with additional resistance to a fluoroquinolone such as levofloxacin or moxifloxacin.
XDR-TB, under the current WHO definition, means MDR/RR-TB with resistance to a fluoroquinolone and at least one additional Group A drug—currently bedaquiline or linezolid.
These definitions have changed over time, so older descriptions of XDR-TB found on the internet may no longer be accurate.
Q8. Is drug-resistant TB curable?
Answer: Yes. Drug-resistant TB is treatable and curable, although treatment is more complex and requires an appropriate regimen based on the patient’s drug-resistance profile and clinical circumstances.
Treatment has improved considerably, with shorter all-oral regimens now available for eligible patients. WHO reports that the global treatment-success rate among people started on MDR/RR-TB treatment increased from 50% in 2012 to 71% in 2022.
Q9. Why is early drug-resistance testing so important?
Answer: If resistance is detected early, the patient can be placed on an appropriate regimen without unnecessary exposure to ineffective medicines. Early diagnosis also reduces the period during which a person with untreated drug-resistant TB may transmit resistant bacteria to others.
Early detection → Correct regimen → Better outcomes → Less transmission
Q10. What should a patient do if treatment becomes difficult?
Answer: The patient should immediately contact the treating healthcare provider rather than stopping treatment. Side effects, financial or social difficulties, stigma, travel, work-related problems and other barriers should be discussed with the treatment team. Many problems can be managed if they are identified early.
Never discontinue TB treatment on your own.
Q11. What can families do to prevent transmission?
Answer: Families can support treatment adherence, encourage medical follow-up, maintain good ventilation, follow cough etiquette and ensure that close contacts are appropriately evaluated. A person with drug-resistant TB should follow the infection-control advice provided by the healthcare team.
Dr S K Arora’s Take-Home Message :
“Drug-resistant TB is not simply a consequence of a patient stopping treatment. Resistance can develop when TB is inadequately treated or an inappropriate regimen is prescribed but it can also be transmitted from one person to another. Therefore, we must detect resistance early, prescribe the correct regimen, support patients throughout treatment and prevent transmission. Never stop or change TB medicines without medical advice.”
TEST FOR RESISTANCE → TREAT CORRECTLY →
COMPLETE TREATMENT → PREVENT TRANSMISSION
End Tobacco → End TB → Save Lives
Dr S K Arora
WHO Awardee I Senior Chest Specialist I TB Expert I Tobacco Control Advocate
