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Tuberculosis

Rapid TB Diagnosis in Resource-Constrained Settings: Novel Colorimetric Test Shows Promise

Strategic Insights

— 1 min read

A study published in BMC Microbiology has presented promising findings on a novel colorimetric test for diagnosing tuberculosis (TB) drug susceptibility in resource-constrained settings. The research, conducted by a team led by Binyam Mebrat from the Armauer Hansen Research Institute in Addis Ababa, Ethiopia, evaluated the performance of the phenotypic thin-layer agar based MDR/XDR-TB Colour Test, also known as the "First Generation (1G) Color Plate Test (TB-CX)". The study compared the test's accuracy with other commonly used methods in the setting.

Key Takeaways:

  • The colorimetric test, known as the Colour Test, was found to detect Mtb isolates resistant to isoniazid, rifampicin, and moxifloxacin with high accuracy, showing a % agreement of 92.6% (95%CI: 84.2-96.7%) for isoniazid and 92.3% (95%CI: 83.7-96.5%) for rifampicin.
  • The median time for determining Mtb resistance or susceptibility for the Colour Test was significantly shorter at 9 days compared to 15 days for the Indirect Proportional Method (IPM) and 19 days for the Mycobacterial Growth Indicator Tube (MGIT) commercially available assay.
  • The study concluded that implementing the Colour Test in clinical settings could make drug-susceptibility testing more accessible and rapid in high TB burden and resource-constrained settings, including in Ethiopia.
  • The research highlighted the need for further evaluation of the Colour Test in larger studies to confirm its accuracy and feasibility in different settings.
  • The study emphasized the importance of early diagnosis and treatment of drug-resistant TB to prevent its spread.

Statistics:

  • Colorimetric test showed % agreement of 92.6% (95%CI: 84.2-96.7%) for isoniazid and 92.3% (95%CI: 83.7-96.5%) for rifampicin.
  • Median time for determining Mtb resistance or susceptibility for the Colour Test was 9 days.
  • Median time for determining Mtb resistance or susceptibility for the IPM assay was 15 days.
  • Median time for determining Mtb resistance or susceptibility for the MGIT commercially available assay was 19 days.

Sources:

  • Performance of the low-cost phenotypic thin-layer agar MDR/XDR-TB Colour Test (first generation, 1G, Color Plate Test) for identifying drug-resistant Mycobacterium tuberculosis isolates in a resource-limited setting. BMC Microbiology, 2025;25(1):652.
  • Bmc, Campus, 4 Crinan St, London N1 9XW, England. (BioMed Central - www.biomedcentral.com/; BMC Microbiology - www.biomedcentral.com/bmcmicrobiol/)
  • Armauer Hansen Research Institute, P.O. Box: 1005, Addis Ababa, Ethiopia.

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