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Scientists Develop Simple Breath Test for TB
A simple breath test may someday show whether a person has a strain of tuberculosis (TB) that will respond to a frontline antibiotic or a type of disease that is resistant to drug therapy, according to scientists at the University of New Mexico at Albuquerque.
The new research was reported in Nature Communications.
The investigators’ prototype technique looks for traces of nitrogen gas emitted by the disease-causing germ Mycobacterium tuberculosis. Strains of the microbe that respond to the drug isoniazid have an enzyme called KatG, which reacts to an antibiotic by releasing nitrogen.
The test involves administering a small amount of isoniazid; waiting for 5 to 10 minutes; and then taking a breath sample, which is chemically analyzed by a mass spectrometer.
A positive result — showing the presence of nitrogen — indicates that the person has a TB infection that can be treated with isoniazid, one of two frontline TB drugs.
So far, the new technique has been tested only in rabbits, and clinical trials are needed to see whether it is safe and accurate in humans — in which case it could be packaged as a portable diagnostic kit, the scientists hope. Further, the prototype will need to be refined or combined with other diagnostics to give physicians a broader view of a patient’s TB status.
If the test gives a negative result, it means either that the person does not have TB or that he or she has an isoniazid-resistant strain, the researchers said. Multidrug-resistant versions of the virus, often deadly, have to be treated with more expensive, alternative medications that take longer to work and can have serious side effects.
TB claimed 1.3 million lives worldwide in 2013, making it the deadliest disease after acquired immune deficiency syndrome (AIDS) to be caused by a single infectious agent, the World Health Organization reported in July.
Conventional sputum laboratory testing for TB bacteria can take up to 6 weeks, which is why investigators are searching for faster, on-the-spot diagnostics.