Extensively Drug-Resistant Tuberculosis
(XDR TB) Overview
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.
Last Reviewed: 05/18/2008
Content Source: Division of Tuberculosis Elimination
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
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