Avoiding the effect of BCG-vaccination in detecting MTB infection with a blood test

¹ School of Public Health, University of Düsseldorf, Germany
² Division of Analytical Cellular Immunology
³ Division of Clinical Infectious Diseases
⁴ Medical Service, Police Academy Schleswig-Holstein, Eutin, Germany
⁵ Division of Mycobacteriology, Research Center Borstel, Germany
⁶ Institution for statutory accident insurance and prevention in the health and welfare services, Hamburg, Germany

	Abstract

BCG-vaccination can confound tuberculin skin test (TST) reactions in the diagnosis of latent TB-infection (LTBI).

We compared the TST with a Mycobacterium tuberculosis (MTB)-specific ELISPOT-assay during an outbreak of MTB infection at a police academy in Germany.

Participants were grouped according to their risk of LTBI in close (n=36) or occasional (n=333) contacts to the index case. For the TST the positive response rate was 53% (19/36) among close and 16% (52/333) among occasional contacts. Fifty-six TST-positive contacts (56/71=78.9%) and 27 TST-negative controls (27/298=9.1%) underwent ELISPOT testing. The OR of a positive test result across the two groups was 29.2 (95% CI 3.5-245.0) for the ELISPOT and 19.7 (95% CI 2.0-190.2) for the TST with a 5 mm cut-off. Of 369 contacts, 158 (42.8%) had previously received BCG-vaccination. The overall agreement between the TST and the ELISPOT was low (=0.16), and positive TST-reactions were confounded by BCG-vaccination [OR 4.8 (95% CI 1.3-18.0)]. In contrast, use of a 10-mm induration cut-off for the TST among occcasional contacts showed strong agreement between TST and ELISPOT in non-vaccinated persons (=0.61).

In BCG-vaccinated individuals the MTB-specific ELISPOT-assay is a better indicator for the risk of LTBI than the TST.

This article has been cited by other articles:

				C. Lange, M. Pai, F. Drobniewski, and G. B. Migliori Interferon-{gamma} release assays for the diagnosis of active tuberculosis: sensible or silly? Eur. Respir. J., June 1, 2009; 33(6): 1250 - 1253. [Full Text] [PDF]

				U. Mack, G. B. Migliori, M. Sester, H. L. Rieder, S. Ehlers, D. Goletti, A. Bossink, K. Magdorf, C. Holscher, B. Kampmann, et al. LTBI: latent tuberculosis infection or lasting immune responses to M. tuberculosis? A TBNET consensus statement Eur. Respir. J., May 1, 2009; 33(5): 956 - 973. [Abstract] [Full Text] [PDF]

				A. Strassburg, C. Jafari, M. Ernst, W. Lotz, and C. Lange Rapid diagnosis of pulmonary TB by BAL enzyme-linked immunospot assay in an immunocompromised host Eur. Respir. J., May 1, 2008; 31(5): 1132 - 1135. [Abstract] [Full Text] [PDF]

				N Viget, G Vernier-Massouille, D Salmon-Ceron, Y Yazdanpanah, and J-F Colombel Opportunistic infections in patients with inflammatory bowel disease: prevention and diagnosis Gut, April 1, 2008; 57(4): 549 - 558. [Abstract] [Full Text] [PDF]

				R. Palazzo, F. Spensieri, M. Massari, G. Fedele, L. Frasca, S. Carrara, D. Goletti, and C. M. Ausiello Use of Whole-Blood Samples in In-House Bulk and Single-Cell Antigen-Specific Gamma Interferon Assays for Surveillance of Mycobacterium tuberculosis Infections Clin. Vaccine Immunol., February 1, 2008; 15(2): 327 - 337. [Abstract] [Full Text] [PDF]

				J-P. Janssens, P. Roux-Lombard, T. Perneger, M. Metzger, R. Vivien, and T. Rochat Quantitative scoring of an interferon-{gamma} assay for differentiating active from latent tuberculosis Eur. Respir. J., October 1, 2007; 30(4): 722 - 728. [Abstract] [Full Text] [PDF]

				R. Diel, P. Wrighton-Smith, and J-P. Zellweger Cost-effectiveness of interferon-{gamma} release assay testing for the treatment of latent tuberculosis Eur. Respir. J., August 1, 2007; 30(2): 321 - 332. [Abstract] [Full Text] [PDF]

				A. Lalvani Diagnosing Tuberculosis Infection in the 21st Century: New Tools To Tackle an Old Enemy Chest, June 1, 2007; 131(6): 1898 - 1906. [Abstract] [Full Text] [PDF]

				R. Diel, A. Nienhaus, and R. Loddenkemper Cost-effectiveness of Interferon-{gamma} Release Assay Screening for Latent Tuberculosis Infection Treatment in Germany Chest, May 1, 2007; 131(5): 1424 - 1434. [Abstract] [Full Text] [PDF]

				C. Jafari, M. Ernst, B. Kalsdorf, U. Greinert, R. Diel, D. Kirsten, K. Marienfeld, A. Lalvani, and C. Lange Rapid Diagnosis of Smear-negative Tuberculosis by Bronchoalveolar Lavage Enzyme-linked Immunospot Am. J. Respir. Crit. Care Med., November 1, 2006; 174(9): 1048 - 1054. [Abstract] [Full Text] [PDF]

				P. D. O. Davies and F. Drobniewski The use of interferon-{gamma}-based blood tests for the detection of latent tuberculosis infection. Eur. Respir. J., July 1, 2006; 28(1): 1 - 3. [Full Text] [PDF]