Test Details: XDR-TB strains are in addition resistant to fluoroquinolones and injectable second-line drugs. This test called GenoType MTBDRsl (MTBDRsl) is a rapid test for detecting resistance to 2nd line TB drugs. In people with MDR-TB, MTBDRsl is used to detect additional drug resistance. The test may be performed on TB bacteria grown in culture from a patient specimen (indirect testing) or on a patient specimen (direct testing), which eliminates delays associated with culture.