Test Details: The BACTEC MGIT 960 susceptibility test is based on growth of the Mycobacterium tuberculosis isolate in a drug-containing tube compared to a drug-free tube (Growth Control). The BACTEC MGIT 960 instrument continually monitors tubes for increasing fluorescence. Analysis of fluorescence in the drug-containing tube compared to the fluorescence of the Growth Control tube is made by the instrument to determine susceptibility results for SIRE and PZA at the concentrations provided by BD. Predefined algorithms compare the growth unit (GU) in the drug-containing tube to the growth unit in the Growth Control tube. A result of susceptible or resistant is reported by the instrument.