<prompt> Case finding in RNTCP is based on -Sputum cultureSputum microscopyX -ray chestMantoux test PCR  <response>: Ans. is b i.e., Sputum microscopy Following information has been added in 22nde of Park o Liquid culture method is now gold standard for TB diagnosis. Confirmation is done from biological characteristics of culture growth and selected molecular biochemical tests. Rapid immunochromatographic assay strip speciation tests provides a definitive identification of M. tuberculosis and is recommended. J Caridge based nucleic acid amplification test : -A second generation NAAT - based TB diagnostic test has sensitivity almost similar to liquid culture. o In microscopy, following methods helps in early diagnosis of large number of cases : - i Fluorescence microscopy by auramine stain, ii Light - emitting diode fluorescence microscopy LEDs. o Drug susceptibility testing provide a definitive diagnosis of drug -resistant TB. A number of techniques are used : i Phenotype method detect drug resistance : - Three methods are used : propoion, absolute concentration and resistance ratio. ii Genotype methods detect molecular mutations responsible for resistance : - e.g., Molecular testing for rifampic in resistance. 