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Tuberculosis Research and Treatment
Volume 2012, Article ID 768723, 4 pages
http://dx.doi.org/10.1155/2012/768723
Clinical Study

The Use of Interferon Gamma Release Assays in the Diagnosis of Active Tuberculosis

1Department of Pneumology, Lungenklinik Heckeshorn, HELIOS Klinikum Emil von Behring, 14165 Berlin, Germany
2Institute of Microbiology, Immunology and Laboratory Medicine, HELIOS Klinikum Emil von Behring, 14165 Berlin, Germany

Received 25 November 2011; Revised 5 January 2012; Accepted 6 January 2012

Academic Editor: Soumitesh Chakravorty

Copyright © 2012 Silvan M. Vesenbeckh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Interferon gamma release assays (IGRAs) are in vitro immunologic diagnostic tests used to identify Mycobacterium tuberculosis infection. They cannot differentiate between latent and active infections. The cutoff suggested by the manufacturer is 0.35 IU/mL for latent tuberculosis. As IGRA tests were recently approved for the differential diagnosis of active tuberculosis, we assessed the diagnostic accuracy of the latest generation IGRA for detection of active tuberculosis in a low-incidence area in Germany. Our consecutive case series includes 61 HIV negative, Mycobacterium tuberculosis culture positive patients, as well as 234 control patients. The retrospective analysis was performed over a period of two years. In 11/61 patients with active tuberculosis (18.0%) the test result was <0.35 IU/mL, resulting in a sensitivity of 0.82. We recommend establishing a new cut-off value for the differential diagnosis of active tuberculosis assessed by prospective clinical studies and in various regions with high and low prevalence of tuberculosis.