Active TB Rapidly Identified in Smear-Negative Tests

Active tuberculosis (TB) was rapidly identified in patients with negative sputum tests using an enzyme-linked immunospot assay.

Immune cells specific to the TB bacilli are concentrated in the airways of patients with active tuberculosis. These cells could be readily identified with the new assay, which is called ELISpot; the results of the test were available in one day. The test can distinguish between latent TB infection, recently redefined as lasting tuberculosis immune responses (LTBI) and active TB by comparing the frequencies of TB-specific T-lymphocytes in the blood versus in the lung. In contrast, the identification of tuberculosis bacilli by culture takes several weeks.

Active tuberculosis (TB) is the seventh-leading cause of death worldwide, and whereas diagnosis of active TB can be rapidly established when bacteria are identified by sputum microscopy, in about half of all cases, the TB bacterium cannot be detected, making another diagnostic option critical in efforts to control the spread of TB.

"In this study, we showed that a differentiation between active pulmonary tuberculosis and LTBI is possible by the ELISpot test," said principal investigator of this [Tuberculosis Network European Trialsgroup] TBNETstudy,'' noted Christoph Lange, M.D., Ph.D., from the Research Center Borstel (Germany).

The findings from the TBNET study appeared in the October 1, 2009, issue of the American Thoracic Society's (New York, NY, USA) American Journal of Respiratory and Critical Care Medicine.

Related Links:
Research Centre Borstel
American Thoracic Society