Most rapid diagnosis of pulmonary TB can be done by ?
Sputum culture
Sputum microscopy
Radiometric BACTEC method
Genexpe
Ans. is 'b' i.e., Sputum microscopy Sputum smear microscopy is the quickest and easiest procedure. But it lacks both sensitivity and specificity. Sputum culture is sensitive and most specific. But it takes 2-8 weeks for culture on routine L.J. media (solid medium). M tuberculosis produces visible colonies on solid media (L.J. media) in 4-8 weeks. Studies have shown that the rate of Isolation of positive cultures was significantly faster with the Bactec method with 87% of the positives being obtained at 7 days and 96% by 14 days. Gene XPe should be used as the initial diagnostic test in individuals suspected of having MDR-TB or HIV-associated TB (strong recommendation)," and "Xpe may be used as a follow-on test to microscopy where MDR and/or HIV are of lesser concern, especially in smear-negative specimens (conditional recommendation). The GeneXpe MTB/RIF assay is a novel integrated diagnostic device for the diagnosis of tuberculosis and rapid detection of RIF resistance in clinical specimens.