sentences:  Multi-drug-resistant tuberculosis
  
  Multi-drug-resistant tuberculosis (MDR-TB) is a form of tuberculosis (TB) infection caused by bacteria that are resistant to treatment with at least two of the most powerful first-line anti-TB medications (drugs), isoniazid and rifampin.Some forms of TB are also resistant to second-line medications, and are called extensively drug-resistant TB (XDR-TB).