PCR colorimetric dot-blot assay and clinical pretest probability for diagnosis of Pulmonary Tuberculosis in Smear-Negative patients


Autoria(s): Scherer, Luciene ; Sperhacke, Rosa ; Jarczewski, Carla ; Cafrune, Patrícia I; Minghelli, Simone ; Ribeiro, Marta ; Mello, Fernanda CQ; Ruffino-Netto, Antonio ; Rossetti, Maria LR; Kritski, Afrânio L
Contribuinte(s)

UNIVERSIDADE DE SÃO PAULO

Data(s)

26/08/2013

26/08/2013

2007

Resumo

Abstract Background Smear-negative pulmonary tuberculosis (SNPTB) accounts for 30% of Pulmonary Tuberculosis (PTB) cases reported annually in developing nations. Polymerase chain reaction (PCR) may provide an alternative for the rapid detection of Mycobacterium tuberculosis (MTB); however little data are available regarding the clinical utility of PCR in SNPTB, in a setting with a high burden of TB/HIV co-infection. Methods To evaluate the performance of the PCR dot-blot in parallel with pretest probability (Clinical Suspicion) in patients suspected of having SNPTB, a prospective study of 213 individuals with clinical and radiological suspicion of SNPTB was carried out from May 2003 to May 2004, in a TB/HIV reference hospital. Respiratory specialists estimated the pretest probability of active disease into high, intermediate, low categories. Expectorated sputum was examined by direct microscopy (Ziehl-Neelsen staining), culture (Lowenstein Jensen) and PCR dot-blot. Gold standard was based on culture positivity combined with the clinical definition of PTB. Results In smear-negative and HIV subjects, active PTB was diagnosed in 28.4% (43/151) and 42.2% (19/45), respectively. In the high, intermediate and low pretest probability categories active PTB was diagnosed in 67.4% (31/46), 24% (6/25), 7.5% (6/80), respectively. PCR had sensitivity of 65% (CI 95%: 50%–78%) and specificity of 83% (CI 95%: 75%–89%). There was no difference in the sensitivity of PCR in relation to HIV status. PCR sensitivity and specificity among non-previously TB treated and those treated in the past were, respectively: 69%, 43%, 85% and 80%. The high pretest probability, when used as a diagnostic test, had sensitivity of 72% (CI 95%:57%–84%) and specificity of 86% (CI 95%:78%–92%). Using the PCR dot-blot in parallel with high pretest probability as a diagnostic test, sensitivity, specificity, positive and negative predictive values were: 90%, 71%, 75%, and 88%, respectively. Among non-previously TB treated and HIV subjects, this approach had sensitivity, specificity, positive and negative predictive values of 91%, 79%, 81%, 90%, and 90%, 65%, 72%, 88%, respectively. Conclusion PCR dot-blot associated with a high clinical suspicion may provide an important contribution to the diagnosis of SNPTB mainly in patients that have not been previously treated attended at a TB/HIV reference hospital.

We thank Fabio Mendonça and Candice Tosi Michelon for laboratory support; CEARGS (Center of studies in AIDS/RS) for statistical support; and health personnel from SPRH. Financial Support: This work was supported by CNPq, REDETB number 62.005/014PADCT and ICIDR, grant number: 1 U19 AI45432

We thank Fabio Mendonça and Candice Tosi Michelon for laboratory support; CEARGS (Center of studies in AIDS/RS) for statistical support; and health personnel from SPRH. Financial Support: This work was supported by CNPq, REDETB number 62.005/014PADCT and ICIDR, grant number: 1 U19 AI45432

Identificador

1471-2458

http://www.producao.usp.br/handle/BDPI/32887

10.1186/1471-2458-7-356

http://www.biomedcentral.com/1471-2458/7/356

Idioma(s)

eng

Relação

BMC Public Health

Direitos

openAccess

Scherer et al; licensee BioMed Central Ltd. - This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Tipo

article

original article