A sputum culture growing acid-fast bacilli on Lowenstein-Jensen medium needs rapid confirmation as Mycobacterium tuberculosis complex before starting treatment. Which rapid method identifies isolates of the M. tuberculosis complex using a secreted protein found only in members of this complex?
- A Immunochromatographic assay for the MPT64 antigen ✓
- B Niacin accumulation test
- C Tween 80 hydrolysis test
- D Catalase and nitrate reduction tests
Correct answer: A. Immunochromatographic assay for the MPT64 antigen
Explanation
The MPT64 protein is a secreted antigen specific to the M. tuberculosis complex, and commercial immunochromatographic strip tests detect it directly from colonies within minutes. Niacin accumulation is positive in M. tuberculosis but requires subculture and biochemical setup and takes longer, so it is slower rather than a rapid confirmatory tool. Tween 80 hydrolysis and catalase or nitrate tests are conventional biochemical reactions that take days and do not specifically target a complex-restricted antigen.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 12th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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