Extensively Drug-Resistant TB
Extensively drug-resistant tuberculosis (XDR TB) is a relatively rare type of multidrug-resistant tuberculosis (MDR TB). It is resistant to almost all drugs used to treat TB, including the two best first-line drugs: isoniazid and rifampin. XDR TB is also resistant to the best second-line medications: fluoroquinolones and at least one of three injectable drugs (i.e., amikacin, kanamycin, or capreomycin).
Because XDR TB is resistant to the most powerful first-line and second-line drugs, patients are left with treatment options that are much less effective and often have worse treatment outcomes.
XDR TB is of special concern for persons 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 higher risk of death once they develop TB disease.
The risk of acquiring XDR TB in the United States appears to be relatively low. However, it is important to acknowledge the ease at which TB can spread. As long as XDR TB exists, the United States is at risk and must address the threat.
- Extensively Drug-Resistant TB (Fact sheet)
The emergence of Mycobacterium tuberculosis strains that cause XDR TB has prompted the issuance of interim guidelines for clinical and research laboratories handling XDR TB specimens.
- Interim Laboratory Biosafety Guidance for Extensively Drug-Resistant (XDR) Mycobacterium tuberculosis strains