Image created by Dr. Michael J. Miller
Researchers from the Postgraduate Institute of Medical Education and Research, Chandigarh; the National Institute of Tuberculosis and Respiratory Diseases, New Delhi; and others have developed a Quick DNA kit that significantly reduces the time required to test for multidrug-resistant tuberculosis (TB). Their new method was found to be as accurate as standard, time-consuming laboratory tests, but significantly more practical for use in developing nations. By using a specialised filter paper called a Trans-Filter, medical workers can now transport patient samples at room temperature, even in the searing heat of the Indian summer. This eliminates the need for complex cold chain refrigeration that often fails in rural areas and could help save thousands of lives in remote communities.
At the heart of this diagnostic breakthrough is the Trans-Filter, a membrane designed to filter out TB bacteria and turn the hazardous biological samples into safe, shippable data. While standard medical testing usually requires liquid sputum to be kept in glass vials and transported to a laboratory in refrigerated trucks, the Trans-Filter allows the sample to be dried, thereby immobilising the tuberculosis bacteria on a sturdy, paper-like surface.
The researchers screened over 1,800 patients to test the new system. The process begins with a patient’s sputum sample, which is first liquefied and then passed through the Trans-Filter device. As the liquid flows through, the membrane acts like a microscopic net, capturing the TB bacteria while letting other fluids pass. The filters are then sterilised and air-dried, which locks the bacterial DNA in the filter paper. These filters are tucked into simple, lightweight zip-lock bags for travel. The researchers found that the Trans-Filter is incredibly resilient. During testing, the membranes were stored at temperatures as high as 50°C (122°F) for up to four weeks. Even in these extreme conditions, which mimic a heatwave in rural India, the bacterial DNA remained perfectly preserved.
Once this filter reaches a central laboratory, the Quick DNA kit employs a method known as heat lysis. By heating the filter in a specialised buffer solution at 80°C for five minutes, the tough outer walls of the TB bacteria are disrupted, releasing their DNA. This genetic material is then analysed using a Line Probe Assay (LPA), a method that detects specific mutations in the bacterial genome. These mutations are biological markers that indicate whether the TB strain is resistant to standard antibiotics such as rifampicin or isoniazid.
Traditionally, extracting DNA from a TB sample was a laborious seven-step process that took nearly an hour to complete. Furthermore, the standard method for transporting TB samples involves packing them on ice and transporting them to a laboratory within 48 hours to prevent spoilage. The Quick DNA kit reduces extraction to a single step that takes only five minutes, and the use of the Trans-Filter ensures that samples remain stable for weeks at room temperature. This eliminates the logistical challenges of maintaining a cold chain in regions with unreliable electricity or long travel distances, thereby making advanced testing available to patients who were previously unreachable.
The researchers, however, noted that the study focused primarily on smear-positive samples, which are those with a high bacterial concentration. Further research may be needed to determine whether the kit is sufficiently sensitive for smear-negative patients, who carry fewer bacteria and are often more difficult to diagnose. Additionally, although the test was highly accurate for most drug resistance markers, a small subset of samples involving a specific gene, inhA, showed lower sensitivity. This was largely because those specific mutations are rarer, sometimes yielding weaker signals that are more difficult for laboratory technicians to interpret.
Nevertheless, the study provides an easy test for a difficult challenge. Tuberculosis remains one of the world’s deadliest infectious diseases, and the rise of drug-resistant strains is a global health emergency. In countries such as India, the time between a patient’s first symptoms and the initiation of appropriate treatment is often far too long. By simplifying sample transport and expediting laboratory work, this new kit helps bridge that gap.
Reference
Gupta, R.K., Chauhan, K., Singhal, R. et al. Development and evaluation of ‘Quick TB DNA Extraction’ kit for the rapid and efficient detection of multidrug-resistant tuberculosis from sputum transported on bio-safe filter. Eur J Clin Microbiol Infect Dis (2026). https://doi.org/10.1007/s10096-025-05312-4
Abstract
Purpose
We recently demonstrated the utility of the 'TB Concentration & Transport' kit for bio-safe, ambient-temperature transport of dried sputum samples on Trans-Filter, along with the 'TB DNA Extraction' kit for efficient DNA extraction from Trans-Filter for use in the Line Probe Assay (LPA) for diagnosing drug-resistant tuberculosis (TB). The present study aimed to develop and evaluate a new ‘Quick TB DNA Extraction’ kit ('Quick DNA' kit) for rapid DNA isolation from Trans-Filter samples and assess its compatibility with LPA for the detection of multidrug-resistant TB (MDR-TB).
Methods
Consecutive presumptive TB/MDR-TB/XDR-TB patients (n = 1823) were screened using LED-FM and/or TBDetect microscopy at 2 Designated Microscopy Centres associated with the National Institute of Tuberculosis and Respiratory Diseases (NITRD), New Delhi. Smear-positive samples (n = 235) were processed in duplicate using the ‘TB Concentration and Transport’ kit. Dried sputum on bio-safe Trans-Filters was transported at ambient temperature, along with sputum samples, in a 3-layer packing in cooling conditions to NITRD Hospital (a National Reference Laboratory). DNA was extracted from Trans-Filters using 'Quick DNA' kit and the ‘TB DNA Extraction’ kit, and from sputum using Hain’s GenoLyse® DNA Extraction kit for first-line LPA for MDR-TB detection.
Results
Quick Kit-LPA and Kit-LPA (LPA with DNA extracted from Trans-Filter using 'Quick DNA' kit and ‘TB DNA Extraction’ kit, respectively) showed similar sensitivity of 88.9% (95% CI: 65.3–98.6) and 88.5% (95% CI: 69.9-97.5) and specificity of 100% (95% CI: 98.2–100) and 99.5% (95% CI: 97.3–99.9) for rifampicin and isoniazid resistance detection, respectively against Direct-LPA (LPA with DNA extracted from sputum samples using GenoLyse kit). User feedback obtained from laboratory technicians corroborated that the one-step 'Quick DNA' kit procedure was rapid (5 minutes), easy to perform, seamlessly integrated with LPA testing, and was suitable as a replacement for Kit-LPA or Direct-LPA.- ,
Conclusion
The gap between drug-resistant TB detection and treatment initiation can be narrowed through Universal-Drug Susceptibility Testing by implementing (i) bio-safe and ambient temperature transport of sputum from primary healthcare centres to central laboratories, and (ii) by using Quick Kit-LPA over Direct-LPA in patients residing in remote areas.