What are 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 caused by bacteria that are resistant to two 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 medicines as directed by your doctor or nurse, 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 can become infected with these drug-resistant bacteria. Drug resistance is more common in people who • have spent time with someone with drug-resistant TB disease • do not take their medicines as directed by their doctor or nurse • develop active TB disease again, after having taken TB medicines in the past • come from areas where drug-resis
