This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
[{'content': 'A patient was sputum negative for TB, but chest Xray was suggestive for TB. Which is the next step according to RNTCP \nSelect and explain. \nA. Liquid culture, B. CB - NAAT, C. Line probe assay, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Reference:Technical and Operational guidelines for TB control in India – 2016\n\xa0\nDIAGNOSTIC ALGORITHM FOR TB:\n\nAll presumptive TB will undergo sputum smear examination\nIf first sputum Is smear positive and not at risk of DR -TB, it will be categorised as microbiologically confirmed TB\nFor 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\nIf first smear is negative and chest X ray is suggestive of TB, 2nd sample will be subjected to smear and CB-NAAT simultaneously\nCB NAAT is Cartridge Based Nucleic Acid Amplification Test\n\n\nThe Gene expert TB test detects DNA sequences specific for M.Tuberculosis and Rifampicin resistance by PCR.\nIt is based on Cepheid Gene expert system , a platform for rapid and simple to use nuclei acid amplification tests (NAAT).\nResults 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.', 'role': 'assistant'}]