Rapid diagnosis of childhood pulmonary tuberculosis by Xpert MTB/RIF assay using bronchoalveolar lavage fluid

Abstract

In order to evaluate the diagnostic accuracy of the Xpert MTB/RIF assay on childhood pulmonary tuberculosis (PTB) using bronchoalveolar lavage fluid (BALF), we evaluated the sensitivity, specificity, positive predictive value, and negative predictive value of Xpert MTB/RIF assay using BALF in comparison with acid-fast bacilli (AFB) microscopy and Mycobacterium tuberculosis (MTB) culture for diagnosing childhood PTB using Chinese "composite clinical reference standard" (CCRS) as reference standard. Two hundred fifty-five children with suspected PTB were enrolled at Beijing Children's Hospital from September 2010 to July 2013. Compared with Chinese CCRS, the sensitivity of AFB microscopy, MTB culture, and Xpert MTB/RIF assay was 8.4%, 28.9%, and 53.0%, respectively. The specificity of three assays was all 100%. Xpert MTB/RIF assay could detect 33.9% of cases with negative MTB culture, and 48.7% of cases with negative AFB microscopy. Younger age (<3 years), absence of BCG scar, and contact with TB patient were found significantly associated with a positive result of Xpert MTB/RIF assay. In conclusion, Xpert MTB/RIF assay using BALF can assist in diagnosing childhood PTB much faster when fiberoptic bronchoscopy is necessary according to the chest radiograph.