What is multidrug-resistant tuberculosis (MDR TB)?
Multidrug-resistant TB is TB that is resistant to at least two of the best anti-TB drugs, isoniazid and rifampicin. These drugs are considered first-line drugs in TB prevention and are used to treat all persons with TB diseases. What is extensively drug resistant tuberculosis (XDR TB)? Extensively drug resistant TB (XDR TB) is a rare type of MDR TB. XDR TB is defined as TB which is resistant to isoniazid and rifampin, plus resistant to any fluoroquinolone and at least one of three injectable second line drugs (i.e., amikacin, kanamycin, or capreomycin). Because XDR TB is resistant to first-line and second-line drugs, patients are left with treatment options that are less effective. XDR TB is of special concern for those infected with HIV infection or other conditions that can weaken the immune system. These persons are more likely to develop TB disease once they are infected, and also have a much higher risk of death once they develop TB. How is TB spread? Drug-susceptible TB and MDR T
