Tuberculosis (TB) is a disease caused by bacteria that are spread from person to person through the air. TB usually affects the lungs, but it can also affect other parts of the body, such as the brain, the kidneys, or the spine. In most cases, TB is treatable and curable; however, people with TB can die if they do not get proper treatment.
Sometimes TB bacteria become resistant to the drugs used to treat TB. This means that the drug can no longer kill the bacteria.
Drug-resistant TB can occur when the drugs used to treat TB are misused or mismanaged. Examples include:
- When people do not complete the full course of treatment;
- When health care providers prescribe the wrong treatment, the wrong dose, or wrong length of time for taking the drugs;
- When the supply of drugs is not always available; or
- When the drugs are of poor quality.
Drug-resistant TB is more common in people who:
- Do not take their TB drugs regularly
- Do not take all of their TB drugs
- Develop TB disease again, after being treated for TB disease in the past
- Come from areas of the world where drug-resistant TB is common
- Have spent time with someone known to have drug-resistant TB disease
Drug-resistant TB is spread the same way that drug susceptible TB is spread. TB is spread through the air from one person to another. The TB bacteria are put into the air when a person with TB disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected.
Multidrug-resistant TB (MDR TB) is caused by an organism that is resistant to at least isoniazid and rifampin, the two most potent TB drugs. These drugs are used to treat all persons with TB disease.
- Multidrug-Resistant TB (Fact sheet)
Extensively drug-resistant TB (XDR TB) is a rare type of MDR TB that is resistant to isoniazid and rifampin, plus any fluoroquinolone and at least one of three injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin).
Because XDR TB is resistant to the most potent TB drugs, patients are left with treatment options that are much less effective.
XDR TB is of special concern for people with HIV infection or other conditions that can weaken the immune system. These people are more likely to develop TB disease once they are infected, and also have a higher risk of death once they develop TB.
The most important way to prevent the spread of drug-resistant TB is to take all TB drugs exactly as prescribed by the health care provider. No doses should be missed and treatment should not be stopped early. People receiving treatment for TB disease should tell their health care provider if they are having trouble taking the drugs.
Health care providers can help prevent drug-resistant TB by quickly diagnosing cases, following recommended treatment guidelines, monitoring patients’ response to treatment, and making sure therapy is completed.
Another way to prevent getting drug-resistant TB is to avoid exposure to known drug-resistant TB patients in closed or crowded places such as hospitals, prisons, or homeless shelters. People who work in hospitals or health-care settings where TB patients are likely to be seen should consult infection control or occupational health experts.
While MDR TB and XDR TB are relatively rare in the U.S., their treatment comes at a terrible price – it is very expensive, takes a long time to complete, disrupts lives, and has potentially life-threatening side effects. A substantial proportion of patients treated for these forms of drug-resistant TB experience serious side effects, including: depression or psychosis, hearing loss, hepatitis, and kidney impairment.
The average cost of treating a person with TB disease increases with greater resistance. Direct costs (in 2010 U.S. dollars) average from $17,000 to treat drug-susceptible TB to $430,000 to treat the most drug-resistant form of the disease (XDR TB). When including productivity losses (e.g., lost income) experienced by patients while undergoing treatment, costs are even higher.