What is multidrug-resistant TB (MDR TB) and extensively drug-resistant TB (XDR TB)?
Sometimes the TB bacteria are resistant to the medicines used to treat TB disease. This means that the medicine can no longer kill the bacteria. Multidrug-resistant TB, or MDR TB, is bacteria that are resistant to two or more of the most important TB medicines: INH and RIF. A more serious form of MDR TB is called extensively drug-resistant TB (XDR TB). XDR TB is a rare type of TB that is resistant to nearly all medicines used to treat TB disease. If you do not take your medicine as your doctor or nurse tells you, the TB bacteria may become resistant to a certain medicine. Also, people who have spent time with someone sick with MDR TB or XDR TB disease can become infected with these multidrug-resistant bacteria. Drug resistance is more common in people who • have spent time with someone with drug-resistant active TB disease • do not take their medicine regularly • do not take all of their medicine as told by their doctor or nurse • develop active TB disease again, after having taken TB
