ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Mohd. Aadam Bin Najeeb1 , Narayana Kamath1, Pooja Naidu2 and Nadeem Amin3
1Department of Microbiology, NAMO Medical Education and Research Institute, Silvassa, Dadra and Nagar Haveli and Daman and Diu, India.
2NAMO Medical Education and Research Institute, Silvassa, Dadra and Nagar Haveli and Daman and Diu, India.
3Health Assurance Hospital, Dhaman, Kuwait.
Article Number: 10733 | © The Author(s). 2025
J Pure Appl Microbiol. 2025;19(4):2768-2778. https://doi.org/10.22207/JPAM.19.4.15
Received: 28 June 2025 | Accepted: 02 September 2025 | Published online: 03 November 2025
Issue online: December 2025
Abstract

Tuberculosis (TB) remains a significant public health challenge in rural India, where access to advanced diagnostics is limited. The Crystal Violet Decolorization (CVD) assay offers a potential low-cost, microscopy-based alternative for detecting Mycobacterium tuberculosis and drug resistance. The CVD assay was assessed for M. tuberculosis detection against CBNAAT and for rifampicin and isoniazid resistance against CBNAAT and culture-based drug susceptibility testing, respectively. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated, with feasibility assessed via turnaround time and cost. Of 350 samples, CBNAAT identified 82 (23.4%) as M. tuberculosis-positive. The CVD assay demonstrated a sensitivity of 92.68% (95% CI: 84.76-97.30%) and specificity of 98.13% (95% CI: 95.70-99.43%) for TB detection, comparable to ZN staining (sensitivity 89.02%, specificity 97.76%). For drug resistance, the CVD assay achieved sensitivities of 85.71% (95% CI: 57.19-98.22%) for rifampicin and 81.25% (95% CI: 54.35-95.95%) for isoniazid, with specificities of 98.53% and 96.77%, respectively. The assay’s turnaround time was 2.5 hours for TB detection and 26.5 hours for resistance testing, with a cost of INR 150 per test, significantly lower than CBNAAT (INR 2000) and culture (INR 2500). The CVD assay offers high diagnostic accuracy for M. tuberculosis detection and good performance for drug resistance screening, with cost-effectiveness and feasibility for rural settings. The assay’s simplicity and affordability make it a promising tool for enhancing TB control in resource-limited regions, supporting India’s National Strategic Plan for Tuberculosis Elimination.

Keywords

Tuberculosis, Crystal Violet Decolorization Assay, Drug Resistance, Rural Diagnostics, Dadra and Nagar Haveli

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© The Author(s) 2025. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.