Multi-drug resistant tuberculosis (MDR-TB) can result when TB treatment is incomplete (or in cases where the wrong or incomplete combination of drugs is prescribed). This is called acquired drug resistance.

The standard treatment for tuberculosis is isoniazid, rifampicin,and pyrazinamide for two months followed by isoniazid and rifampicin for four months. A certain amount of tuberculosis germs (bacteria) are naturally resistant to one or another of the standard drugs prescribed. This is why it is important to use a combination of drugs. If treatment is stopped before all the bacteria are killed (because the patient feels better, can't get to the clinic, or because of a drug shortage) OR if an incomplete combination of drugs is given, the resistant bacteria can grow and cause the symptoms to return.

Drug resistant forms of the disease take longer to cure, and require more and more expensive drugs to treat. Besides the added time and expense required for treatment, cure rates are low and fatality rates are high.

Bacterial cultures grown in the laboratory can tell doctors which drugs kill the bacteria most effectively for that particular strain. However in poor countries many TB services do not have the resources or facilities for culture, or the resources to provide the drugs needed.

If a person has drug resistant TB, anyone they pass it on to will also have the same resistance. This is called primary drug resistance. Outbreaks of Multi-drug resistant tuberculosis (MDR-TB) have become a very serious problem in most countries of the Commonwealth of Independent States (which is made up of Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russian Federation, Tajikistan, Turkmenistan and Ukraine) - more serious than in any other place in the world. The main reasons are improper treatment, intermittent drug shortages and poor monitoring of TB patients under treatment.

All of TB Alert's projects prioritise ensuring that all patients complete their treatment so that drug resistance can be prevented. In the UK for instance we produce leaflets and a diary to help patients understand the need to continue their drugs and remember when they have taken them. We also provide a hardship fund to ensure patients are not prevented from completing treatment due to financial reasons.

A standardized drug regimen, directly observed treatment (DOT), a good supply of high quality drugs, and isolation of infectious patients with drug resistant forms of the disease are some of the main ways to prevent the spread of MDR-TB.