A simple diagnostic test to detect tuberculosis in humans

Tuberculosis (TB) represents a growing worldwide healthcare burden. Second only to HIV in terms of its global impact, TB infected 8.5 million people and caused 1.4 million deaths in 2011. If these statistics are to improve, early detection is critical.

Led by Taha Roodbar Shojaei and Mohamad Amran Mohd Salleh of Universiti Putra Malaysia, the international research team set out to develop a sensitive new system that could quickly and reliably detect TB in humans. One of their biggest hurdles was to differentiate people infected with tuberculosis from those who have received the bacillus Calmette-Guerin (BCG) vaccine for tuberculosis.

Using modified quantum dots, gold nanoparticles and single strand DNAs, the team developed a layered biosensor that not only detects TB in patients' sputum but also differentiates positive results from samples of vaccinated people. Using the new sensor, the team has conducted preliminary tests on 50 clinical samples from patients in Tehran who were suspected of having TB. While current TB diagnostic tests based on the polymerase chain reaction technique for isolating DNA have an approximately 80% success rate for both sensitivity (the ability to correctly identify the disease) and specificity (the ability to rule out other conditions such as BCG vaccination), the new method was rated between 86.6% and 94.2% accurate.

The researchers believe they have developed a simple, rapid, sensitive and specific detection method with an affordable cost. Their biosensor requires small amounts of sputum and could therefore be an appropriate detection technique where limited sample volumes are available.

In 2015, the team plans to further enhance its biosensor system with carbon nanoparticles instead of gold. If time permits, the team will develop a working device and interface to simplify the detection of TB, perhaps with a smartphone app.