Tuberculosis is still a major health problem in much of the world. It was the primary cause of death from an infectious disease until the COVID-19 pandemic, and worldwide, it is the thirteenth leading cause of death. It is responsible for the deaths of about 1.4 million people annually, and is especially deadly to kids. The World Health Organization (WHO) has also estimated that around three million cases of TB go undiagnosed every year, a group known as the "missing millions."
But a new invention could help reveal those cases. A new technique called dielectrophoresis could dramatically improve TB diagnosis and treatment in areas where TB rates are high and healthcare infrastructure is poor. Improving this situation could reduce the burden that TB creates for public health. The work has been reported in The Journal of Molecular Diagnostics.
TB is a highly infectious but treatable disease, and right now, the public health problem of TB is not improving, noted lead study investigator Philip D. Butcher, PhD, St George's, University of London. Butcher's team partnered with a biomedical technology company called QuantuMDx to create a portable, fast, inexpensive, and accurate TB test that diagnoses the diseases from sputum, or mucus that is expelled through coughing.
"We saw an opportunity by collaborating on a new chip-based technology using dielectrophoresis to selectively isolate Mtb [Mycobacterium] bacilli from sputum samples."
A microfluidic lab-on-a-chip device was developed in which patient sputum is processed by dielectrophoresis so that Mtb bacilli can be isolated for visual inspection and used for quantitative PCR (qPCR) or drug-susceptibility assays. In dielectrophoresis, dielectric characteristics caused certain cells or particles to be attracted or repelled; in this case, TB-causing Mtb bacteria are captured and the rest of the sputum is washed away. The technology is called CAPTURE-XT.
The test was validated with sputum that had already been assessed. The method correctly identified negative samples every time, and positive samples 87 percent of the time. For those with a serious infection, the diagnosis was correct 100 percent of the time.
The video shows Mycobacterium tuberculosis bacteria particles as white fluorescent spots, and as the sputum flows across the electrodes on the chip, bacteria accumulates. Some electrodes are eventually filled and direct visual confirmation can be made.
"The CAPTURE-XT technology is truly revolutionary and will have an impact in many different diseases from sepsis to oncology. This application in Mtb is truly exceptional as its ultra-low cost and ultra-high sensitivity will profoundly improve equitable access to quality diagnoses for hundreds of millions of people," said Jonathan O'Halloran, PhD, founder and Chief Executive Officer of QuantuMDx Group. Ltd.
Sources: Elsevier via Medical Express, Journal of Molecular Diagnostics