Xpert MTB/RIF (CBNAAT), used widely under NTEP, diagnoses tuberculosis and rifampicin resistance by targeting which bacterial component?
- A rpoB gene of Mycobacterium tuberculosis ✓
- B katG gene conferring isoniazid resistance
- C 16S ribosomal RNA of mycobacteria
- D IS6110 insertion sequence only
Correct answer: A. rpoB gene of Mycobacterium tuberculosis
Explanation
The cartridge-based nucleic acid amplification test amplifies a segment of the rpoB gene, which codes for the beta subunit of RNA polymerase. Over 95 percent of rifampicin-resistant strains carry mutations here, so detection of an rpoB mutation serves as a proxy for multidrug-resistant TB risk and triggers referral to a second-line drug resistance panel. katG relates to isoniazid and IS6110 is used in some other molecular assays, not this one.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.