New TB Test Could Offer Faster and More Accurate Diagnosis

At the recent National Meeting & Exposition of the American Chemical Society (ACS) in Philadelphia, researchers from Stanford University presented their findings on a new test they have developed for tuberculosis (TB) which offers a promising new quick and easy diagnostic tool for doctors in developing nations.

The World Health Organization classifies TB as one of the top killer infectious diseases affecting people around the world. In 2014 alone, 9.6 million people became infected with the disease, and 1.5 million of them died from the illness. One million of those infected, and 140,000 of those who died, were children.

TB is caused by Mycobacterium tuberculosis, which most often attacks the lungs but can also affect other organs. Pulmonary TB infections may cause symptoms in the lungs such as a bad and prolonged cough, pain in the chest, and coughing up of blood or phlegm from deep inside the lungs. In addition to those symptoms, people infected with TB may experience weakness, fatigue, loss of appetite, weight loss, fever, chills and night sweats.

According to the Centers for Disease Control, TB spreads from person to person when a person who is infected releases the bacteria into the air by coughing, speaking, or singing. When a healthy person breathes in the TB bacteria, it can enter into the lungs and other parts of the body and begin to multiply. Although the body can often fight latent TB bacteria that enter the body, thus preventing illness, the bacteria can become active and multiply in those individuals who are unable to fight the infection, such as those with weakened immune systems, young children, individuals who have been in parts of the world with higher rates of TB, and those who work with people at high risk for TB.

Individuals with latent TB infection still need treatment to prevent the onset of disease, and up to 10% of individuals who don’t receive treatment will go on to develop TB at some point in their lifetime. Latent TB treatments are often administered for several months to prevent the onset of disease.

A press release issued by the ACS detailed the new test which they say will make the diagnosis of TB simpler, faster, and more accurate. Current tests for the infection include chest X-ray, which is rarely available in the poorer and worst-hit regions of South Asia and Africa, as well as tests of blood, saliva, or skin, which need to be sent to a lab. These tests can be prone to errors and results can take a long time to come back to the doctors.

This novel TB test emerged as researcher Carolyn R. Bertozzi, PhD, and her team at Stanford were studying the glycolipids in TB. Glycolipids are molecules in the cell walls of the bacteria that cause the disease, and are made up of the sugar trehalose linked with lipids or fats. When the researchers exposed modified forms of trehalose to the TB bacteria, the microbes would metabolize and integrate them into their glycolipids. By attaching a fluorescent green dye molecule to the sugars, they found that the bacteria cell that picks it up then glows green.

With this discovery, the researchers saw a potential new approach to testing saliva for TB, but needed a more sensitive dye that did not tint every component of the saliva. Using instead a solvatochromic dye that only glows once inside the cell walls and attaching it to the trehalose, the researchers found that they had developed a quick and easy test for TB that can give a speedy diagnosis. After adding the dye mixture to a saliva sample from a patient, a technician can note a positive diagnosis if anything appears to glow under the microscope in as little as one hour.

Of note is that this new dye test only works on live cells, and so it can indicate when a treatment for TB is working and the bacteria cells are dying.

Trial tests for this new diagnostic tool for TB began in South Africa in June. The Stanford research team is currently building on their research to hopefully shed light on new ways to battle TB.