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Novel assay detects TB in early stages of disease

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SAN DIEGO — An assay using surface-enhanced Raman spectroscopy detected low concentrations of tuberculosis in early stages of infection, according to data presented at IDWeek 2015.

Jennifer Granger, PhD, from the Nano Institute at the University of Utah, and colleagues developed a diagnostic platform that can be used in resource-limited settings that is capable of detecting TB infection in very early stages. The assay is designed to capture low concentrations (roughly 1 nM) of antigenic TB biomarkers, specifically lipoarabinomannan (LAM), from serum samples.

Jennifer Granger

“Our assay is very similar to [the enzyme-linked immunosorbent assay (ELISA)], but we can get enhancement in our readout by taking advantage of surface-enhanced Raman spectroscopy, or SERS,” Granger told Infectious Disease News. “It gives us the opportunity to develop unique labels on nanoparticles. When you bring them closer to the surface, you see an enhancement of those labels, which allows us to detect things at very low levels.”

The efficacy of the assay was assessed during a proof-of-principal study. Granger and colleagues analyzed serum samples from 77 patients with culture-confirmed TB and compared them with 39 negative serum specimens.

Using SERS, the researchers identified measurable LAM levels of 1 ng/mL or less in 69 specimens, according to data presented by Granger. The assay performed with 90.6% clinical sensitivity in positive samples and 100% specificity in negative samples.

Granger said the preliminary results indicate that SERS has the potential to be a diagnostic tool for TB. The researchers will further investigate LAM as a biomarker for TB in a cohort of 1,000 patients. They also are exploring the diagnostic role of other biomarkers in serum samples, which can detect TB antigen in patients with nonpulmonary forms of the disease.

“Our colleagues at Colorado State are doing a similar test and developing this technology, but urine-based, so we’ve been working with them just to compare and contrast how the signals for LAM in serum and in urine can compare to each other,” Granger said. – by Stephanie Viguers

Reference:

Granger J, et al. Abstract 588. Presented at: IDWeek; Oct. 7-11, 2015; San Diego.

Disclosure: Granger reports no relevant financial disclosures.