Diagnosing TB with the Xpert Assay vs. AFB Smear Microscopy

The Xpert assay was more accurate and faster than traditional acid-fast bacillus smear microscopy for diagnosing pulmonary tuberculosis.

The acid-fast bacillus (AFB) smear, invented more than 100 years ago, is still employed for diagnosing active pulmonary tuberculosis (TB). However, AFB smear microscopy is known to have a low sensitivity and, because it cannot distinguish between Mycobacterium tuberculosis and nontuberculous mycobacteria, low specificity. Genomic methods that are currently available, such as the Xpert MTB/RIF assay, can rapidly and accurately detect the presence of M. tuberculosis in clinical samples in a semiquantitative manner.

Now, investigators in South Korea have compared the diagnostic performance of the Xpert assay and AFB smear microscopy using consecutive sputum samples from 2952 patients with suspected pulmonary TB. Of these samples, 8.9% grew M. t…

Reviewing Author

Neil M. Ampel, MD

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Editorial BoardsUpToDate

Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

Neil M. Ampel, MD

Disclosures

Editorial BoardsUpToDate

Leadership Positions in Professional SocietiesCoccidioidomycosis Study Group (Past President, Secretary, Treasurer)

Diagnosing TB with the Xpert Assay vs. AFB Smear Microscopy

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Reviewing Author