Blood Test Identifies Those at High Risk of Developing Human Tuberculosis

By LabMedica International staff writers
Posted on 26 Apr 2022

Image: Actiphage is a promising new diagnostic test for tuberculosis infection (Photo courtesy of Pexels)

Nearly a quarter of the world’s population has latent tuberculosis infection (LTBI), which is asymptomatic and a reservoir for future disease. A small proportion has incipient TB, defined as a state of higher risk of developing to TB unless treated. However, separating these individuals from everyone else with LTBI is currently problematic. New research presented at ECCMID 2022 (European Congress of Clinical Microbiology & Infectious Diseases) has shown that Actiphage, a new blood test for Mycobacterium tuberculosis (Mtb) can improve identification of those at risk of progressive tuberculosis infection, offering potential for a rapid, non-invasive biomarker for early screening of asymptomatic individuals.

Researchers from the University of Leicester (Leicester, UK) and PBD Biotech Ltd. (Suffolk, UK) conducted a clinical trial of Actiphage, a promising new diagnostic for tuberculosis infection. The trial has shown for the first time that live bacteria can be detected in the blood of people with incipient TB infection. Actiphage offers almost three times greater specificity than the gold standard IGRA test for this state of latent infection. The ground-breaking clinical trial shows the potential for using Actiphage as a pathogen directed biomarker to identify those with incipient TB, a key WHO research priority.

“The trial aimed to investigate whether there is an association between the presence of Mycobacterium tuberculosis (Mtb) circulating in the blood of individuals who are otherwise completely well, and evidence of progressive TB infection,” said lead author, Jee Whang Kim of the Leicester Tuberculosis Research Group (LTBRG). “The results show that by using Actiphage, we were successful in isolating Mtb in the blood of a subset of individuals with latent TB and also in demonstrating an association with radiological and microbiological evidence of progressive TB infection. Compared with IGRA, Actiphage was almost three times more specific at identifying this group. To our knowledge, this is also the first time that viable Mtb infection has been isolated in people with a clinical diagnosis of latent TB infection.”

“Although TB is now second to COVID as the leading cause of death from an infectious disease, the future impact of TB on human health is likely to far exceed the COVID pandemic. TB prevention through identification and treatment of at-risk LTBI is a key long-term strategy for TB control and elimination,” added Dr. Pranab Haldar from the University of Leicester who is the lead clinician on the trial. “Our findings demonstrate the potential utility of Actiphage as a pathogen directed biomarker for improving risk stratification of LTBI that can potentially complement the evolving panel of host-directed immune biomarkers. We hope our findings will stimulate further research to develop other pathogen directed biomarkers for this purpose.”

Related Links:
University of Leicester
PBD Biotech Ltd.