Reference:Technical and Operational guidelines for TB control in India – 2016   DIAGNOSTIC ALGORITHM FOR TB:All presumptive TB will undergo sputum smear examination If first sputum Is smear positive and not at risk of DR -TB, it will be categorised as microbiologically confirmed TB For Smear positive and presumptive MDR-TB , CB-NAAT will be performed to rule out Rifampicin resistance, and categorised as microbiologically confirmed drug sensitive RIF resistant TB If first smear is negative and chest X ray is suggestive of TB, 2nd sample will be subjected to smear and CB-NAAT simultaneously CB NAAT is Cartridge Based Nucleic Acid Amplification TestThe Gene expert TB test detects DNA sequences specific for M.Tuberculosis and Rifampicin resistance by PCR. It is based on Cepheid Gene expert system , a platform for rapid and simple to use nuclei acid amplification tests (NAAT). Results are obtained within 90 minutes. It has minimal biohazard and needs very little technical training since unprocessed sputum samples are used to identify the results in a realtime format.