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Open Access Research article

Performance of seven serological assays for diagnosing tularemia

Valérie Chaignat1, Marina Djordjevic-Spasic2, Anke Ruettger3, Peter Otto1, Diana Klimpel1, Wolfgang Müller1, Konrad Sachse3, George Araj4, Roland Diller1 and Herbert Tomaso1*

Author Affiliations

1 Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Naumburger Str. 96a, Jena 07743, Germany

2 Clinical Centre Niš, Clinic for Infectious Diseases, Bulevar Zorana Djindjica 48, Niš 18000, Serbia

3 Institute of Molecular Pathogenesis, Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Naumburger Str. 96a, Jena 07743, Germany

4 Clinical Microbiology, Department of Pathology & Laboratory Medicine, American University of Beirut Medical Center, Beirut 1107-2020, Lebanon

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BMC Infectious Diseases 2014, 14:234  doi:10.1186/1471-2334-14-234

Published: 5 May 2014

Abstract

Background

Tularemia is a rare zoonotic disease caused by the Gram-negative bacterium Francisella tularensis. Serology is frequently the preferred diagnostic approach, because the pathogen is highly infectious and difficult to cultivate. The aim of this retrospective study was to determine the diagnostic accuracy of tularemia specific tests.

Methods

The Serazym®Anti-Francisella tularensis ELISA, Serion ELISA classic Francisella tularensis IgG/IgM, an in-house ELISA, the VIRapid® Tularemia immunochromatographic test, an in-house antigen microarray, and a Western Blot (WB) assay were evaluated. The diagnosis tularemia was established using a standard micro-agglutination assay. In total, 135 sera from a series of 110 consecutive tularemia patients were tested.

Results

The diagnostic sensitivity and diagnostic specificity of the tests were VIRapid (97.0% and 84.0%), Serion IgG (96.3% and 96.8%), Serion IgM (94.8% and 96.8%), Serazym (97.0% and 91.5%), in-house ELISA (95.6% and 76.6%), WB (93.3% and 83.0%), microarray (91.1% and 97.9%).

Conclusions

The diagnostic value of the commercial assays was proven, because the diagnostic accuracy was >90%. The diagnostic sensitivity of the in-house ELISA and the WB were acceptable, but the diagnostic accuracy was <90%. Interestingly, the antigen microarray test was very specific and had a very good positive predictive value.

Keywords:
Serology; Tularemia; Diagnostic sensitivity; Diagnostic specificity