Topic Overview

People infected with tuberculosis (TB) bacteria that are antibiotic-resistant have what is called drug-resistant tuberculosis. There are different types of drug-resistant TB.

• Mono-resistant TB happens when the bacteria don't respond to one first-line drug.
• Multidrug-resistant TB happens when the bacteria don't respond to at least the two strongest TB drugs (isoniazid and rifampin).
• Poly-resistant TB happens when the bacteria don't respond to more than one first line drug other than isoniazid and rifampin.
• Extensively drug-resistant TB happens when the bacteria are resistant to isoniazid, rifampin, and several other medicines used to treat TB. This is rare.

People with drug-resistant tuberculosis need special treatment programs. Treatment usually involves several medicines.

• The choice of medicines depends on the results of sensitivity testing .
• It is very important to take every dose of medicine. So directly observed therapy (DOT) usually is done. During DOT, a health professional watches you take every dose of medicine.
• Treatment is continued until TB bacteria can no longer be found in two sputum samples taken a month apart. This may take 18 months or longer in people with multidrug-resistant TB (MDR-TB).

Some TB bacteria have become resistant to all of the antibiotics that are commonly used to treat TB. This is sometimes called totally resistant tuberculosis (TDR-TB). ^{footnote 1} A TB infection of this type is very difficult to treat.