Recent Development in the Molecular Diagnosis of Tuberculosis

JOURNAL TITLE: Bengal Physician Journal

Author
1. Supriya Sarkar
ISSN
DOI
10.5005/jp-journals-10070-5204
Volume
5
Issue
2
Publishing Year
2018
Pages
6
Author Affiliations
    1. College of Medicine and Sagore Dutta Hospital, Kolkata, West Bengal, India
  • Article keywords

    Abstract

    Molecular diagnostic tests are the molecular techniques used to detect a nucleic acid of organisms. They have revolutionized the diagnosis of tuberculosis (TB) and drug resistance. Cartridge-based nucleic acid amplification tests (CBNAAT) and line probe assay (LPA) have been accepted in our national tuberculosis control program. CBNAAT has the advantage that it can be done from crude samples and smear negative samples and results can be obtained by 2 hours. But CBNAAT can detect rifampicin resistance only.

    On the contrary, LPA can detect rifampicin and isoniazid resistance, but the test can only be done at regional or national levels. LPA cannot be done from smear negative or crude specimens. The recent version of LPA (version 2.0) can overcome that problem. Second line LPA can detect the drug resistance against fluoroquinolones, second line injectable drugs and ethambutol (in version 1.0 only). GeneXpert Omni is a portable technique having 4-hour lasting battery using the same cartridge. GeneXpert Ultra has more sensitivity due to larger chamber size and due to two additional probes. Ultra may replace Xpert soon as it will be more effective against smear-negative TB, TB in HIV positive persons, childhood TB, and extrapulmonary TB. With the introduction of molecular diagnostic tests for TB, we will be able to reduce the time of diagnosis of TB and drug resistance. Thereby, we will be able to start first line or second line anti-tubercular chemotherapy earlier, and that will help us to achieve our goal in controlling TB.

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