Tuberculosis is a bacterial infection caused by species of the Mycobacterium tuberculosis (TB, MTB) complex. A drug resistant strain is defined as resistance to at least one primary drug used to treat tuberculosis. A multidrug resistant TB (MDR-TB) is defined as resistance to at least isoniazid and rifampicin, the two most effective anti-TB drugs, and an extensively drug resistant TB (XDR-TB) is defined as a MDR-TB strain with additional resistance to any fluoroquinolone and at least one injectable second-line TB drug (e.g., amikacin, kanamycin, or capreomycin). In 2017, it was estimated that >5% of incident new TB cases in the world had MDR/RR-TB. The frequency of MDR-TB varies according to region and is higher among previously treated patients.
cobas® MTB-RIF/INH for use on the cobas® 6800/8800 Systems is an automated, qualitative real-time PCR test designed as a reflex test together with cobas® MTB to detect Rifampicin-resistance associated mutations of the rpoB gene and Isoniazid-resistance associated mutations in the katG and inhA genes, of M. tuberculosis. The test is intended for use on either acid-fast bacilli (AFB) smear-positive or smear-negative, raw sputum, and digested and decontaminated (N-acetyl-L-cysteine/ NaOH treated) sputum and bronchial alveolar lavage (BAL) samples, that tested positive for M. tuberculosis complex by cobas® MTB. Detection of wild-type MTB complex DNA serves as Internal Control to monitor the entire sample preparation and PCR amplification process. In addition, the test utilises a low titer positive and a negative control.