MDR TB - Multi drug resistant TB

What is MDR TB?

MDR TB is a particular type of drug resistant TB. It means that the TB bacteria that a person is infected with are resistant to two of the most important TB drugs, isoniazid (INH) and rifampicin (RMP). If bacteria are resistant to certain TB drugs this means that the drugs don’t work.

Other drugs then need to be taken by the person if they are to be cured of TB.

MDR TB is also known as Multi Drug Resistant TB.

What is RR TB?

RR means rifampicin resistant TB

People with RR TB are resistant to rifampicin. They may or may not have resistance to other drugs. MDR/RR TB means patients with MDR  TB as well as patients with TB resistant to rifampicin.

For many years MDR TB has been the most basic form of drug resistant TB, and the type of TB for which many statistics were collected. Then in 2016 RR TB started to become more widely discussed because many people are now being diagnosed with TB using the Genexpert test. The Genexpert test detects resistance to rifampicin as well as resistance to isoniazid.

How do you get MDR TB or RR TB?

There are two main ways that you can get them. Firstly you can get them if you don’t take your drugs exactly as you have been instructed to by your health care provider. You may also get them if you are not taking the correct drugs. This could possibly be because your bacteria are resistant to more drugs than your health care provider realised. Maybe you have undiagnosed XDR TB. This is referred to as acquired TB.

You can also get them if you get TB bacteria from another person who already has MDR or RR TB. This is known as primary TB. It used to be believed that most people have acquired TB. But it is now realised that many more people than were previously realised have primary TB.

How many people have it?

There were an estimated 484,000 incident cases in 2018. Half of these cases were in India (27%), China (14%) and the Russian Federation (9%). There is more about TB in India.

In 2018 an estimated 3.4% of new cases and 18% of previously treated cases had MDR/RR-TB. The highest proportions are in several countries of the former Soviet Union (above 25% in new cases and above 50% in previously treated cases).

Can MDR TB cause people to die?

In 2018 MDR TB and RR TB caused approximately 214,000 deaths.

Treatment of MDR TB

A large number of drugs have to be taken for the treatment of MDR TB

In 2019 the World Health Organisation (WHO) recommended that there should be a major change to the treatment for drug resistant TB with shorter regimens being made available for many patients.

Previously treatment for drug resistant TB had often required a large number of drugs to be taken taken for up to two years. Also the drugs often caused severe side effects in patients. So various efforts were being made to develop shorter regimens which were easier to take.

The first shorter and easier to tolerate regimen was known as the Bangladesh regimen. It appears to have a higher cure rate than “standard” regimens.

How common is it?

The table below shows the estimated number of cases for each World Health Organisation (WHO) region.

Estimated incidence of MDR/RR-TB in 2018 for WHO regions

Estimated incidence of MDR/RR-TB in 2018 for 30 high MDR-TB burden countries

There are 30 high burden countries for MDR TB.

The table below shows the estimated number of cases for each “high burden” country. But these are only the estimates for the number of cases among those cases of pulmonary TB notified to WHO. There will in addition have been many cases of MDR TB among those cases of TB which were either not detected and/or not notified.

Page updating

This page was last updated in December 2022.
Author Annabel Kanabus

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