When tuberculosis (TB) patients do not take their medicine as prescribed, the TB bacteria may become resistant to a certain drug. This means that the drug can no longer kill the bacteria. Drug resistance is more common in people who:
- Come from areas where drug-resistant TB is common (Southeast Asia, Latin America, Haiti, and the Philippines)
- Develop TB disease again, after having taken TB medicine in the past
- Do not take all of their prescribed medicine
- Do not take their medicine regularly
- Have spent time with someone with drug-resistant TB disease
Sometimes the bacteria become resistant to more than one drug. This is called multidrug-resistant TB, or MDR TB. This is a very serious problem. People with MDR TB disease must be treated with special drugs. These drugs are not as good as the usual drugs for TB and they may cause more side effects.
Also, some people with MDR TB disease must see a TB expert who can closely observe their treatment to make sure it is working.
People Who Have Spent Time with Someone Sick
People who have spent time with someone sick with MDR TB disease can become infected with TB bacteria that are resistant to several drugs. If they have a positive skin test reaction, they may be given preventive therapy. This is very important for people who are at high risk of developing MDR TB diseases, such as children and HIV-infected people.