European Society of Mycobacteriology - Instituto Nacional de Saúde ...

PP-88
Evaluation of the applicability
of serodiagnosis for tuberculosis in Portugal
Carina Ferreira 1 , Andrea Afonso 2 , Raquel Duarte 3 , Konstantin Lyashchenko 4 , Anabela
Silva 5 , Filomena Rodrigues 5 , Anabela Miranda 5 , Margarida Tavares 6 , Cátia Caldas 6 , Fátima
Valente 2 , António Valente 2 , Olga Vasconcelos 7 , Joana Amado 7 , Margarida Correia-Neves 1
1 - Life and Health Sciences Research Institute (ICVS), University of Minho, Braga, Portugal
2 - Centro de Saúde de Bragança, Bragança, Portugal
3 - Centro de Diagnóstico Pneumológico de Vila Nova de Gaia, Portugal
4 - Chembio Diagnostic Systems, New York, USA
5 - Centro de Tuberculose e Micobactérias, Instituto Nacional de Saúde Dr Ricardo Jorge, Delegação do Porto, Portugal
6 - Serviço de Doenças Infecciosas, Hospital de São João, Porto, Portugal
7 - Hospital Joaquim Urbano, Porto, Portugal
Diagnosis of tuberculosis requires laboratory techniques to complement clinical information. Among the different techniques
in use, the only accurate diagnostic method is based on the search for Mycobacterium tuberculosis growth in
cultures of human biological samples, usually sputum. However, this approach is long, lacks sensitivity for samples with
low bacterial load, and is invasive in the case of non-pulmonary tuberculosis. In order to overcome these constraints,
several novel methodological approaches are under evaluation. Among these is the determination of tuberculosis-specific
antibodies in the sera - serodiagnostic methods. Validation of serodiagnosis tests in any given country is mandatory, since
sensitivity and specificity vary depending on factors such as the composition and frequency of environmental mycobacteria,
previous vaccination with BCG, prevalence of tuberculosis and other diseases, and host genetic background. We
evaluated the specificity and sensitivity of two serodiagnosis tests: TB STAT-PAK II - an immunochromatographic test for
the detection of antibodies to Mycobacterium tuberculosis; and MAPIA - Multi-Antigen Print Immunoassay (both developed
at Chembio Diagnostics, NY, USA). The specificity of the tests was very high, ranging from 94 to 100% depending
on the test and control population analysed. The sensitivity was 37 and 54% for TB STAT-PAK II and MAPIA, respectively,
and it increased during the first 3 months of treatment, for TB STAT-PAK II. Interestingly, when the smear results were
combined with the ones from the TB STAT-PAK II, the sensitivity increased from 71 (just smear) to 79%. Thus, taking into
consideration the great specificity of the TB STAT-PAK II, its use for smear negative patients could increase the rate of
detection in early TB diagnostic.
160 ESM 2009