Urine test developed to test for tuberculosis

December 14, 2017

Mycobacterium tuberculosis (Mtb) infected Human Dendritic Cells. Mtb appear as isolated or grouped red-purple stained rods. Kinyoun staining. Optical mycrocoscopy 20x.

An international team of researchers has developed a urine test that can be used to detect tuberculosis (TB) in human patients. In their paper published in Science Translational Medicine, the group describes how they developed the test and how well it works.

Scientists have been trying for some time to develop an easy way to test people for a Mycobacterium tuberculosis infection. The two main types of tests currently in use, the skin test and the culture test, require a high degree of expertise. In this new effort, the researchers claim to have developed a urine test that can be conducted by untrained health care workers.

TB is a bacterial infection that primarily infects the lungs—10 million people are infected annually, and more than a 1.5 million of those victims die. Earlier detection and treatment, it is believed, would reduce suffering and fatalities.

Infographic explaining the advantages of a new test for tuberculosis

Map showing worldwide prevalence of tuberculosis infections.

An accurate urine test for pulmonary tuberculosis (TB), affecting 9.6 million patients worldwide, is critically needed for surveillance and treatment management. Past attempts failed to reliably detect the mycobacterial glycan antigen lipoarabinomannan (LAM), a marker of active TB, in HIV-negative, pulmonary TB–infected patients' urine (85% of 9.6 million patients). We apply a copper complex dye within a hydrogel nanocage that captures LAM with very high affinity, displacing interfering urine proteins. The technology was applied to study pretreatment urine from 48 Peruvian patients, all negative for HIV, with microbiologically confirmed active pulmonary TB. LAM was quantitatively measured in the urine with a sensitivity of >95% and a specificity of >80% (n = 101) in a concentration range of 14 to 2000 picograms per milliliter, as compared to non-TB, healthy and diseased, age-matched controls (evaluated by receiver operating characteristic analysis; area under the curve, 0.95; 95% confidence interval, 0.9005 to 0.9957). Urinary LAM was elevated in patients with a higher mycobacterial burden (n = 42), a higher proportion of weight loss (n = 37), or cough (n = 50). The technology can be configured in a variety of formats to detect a panel of previously undetectable very-low-abundance TB urinary analytes. Eight of nine patients who were smear-negative and culture-positive for TB tested positive for urinary LAM. This technology has broad implications for pulmonary TB screening, transmission control, and treatment management for HIV-negative patients.
Journal reference: Science Translational Medicine