A Test for More Accurate Diagnosis of Pulmonary Tuberculosis.

Abstract

Xpert <i>Mycobacterium tuberculosis</i> and rifampicin (MTB/RIF) Ultra assay has increasingly been used in adult tuberculosis diagnosis, but data relating to its diagnostic accuracy in children are lacking. Because a qualified sputum specimen is difficult to obtain in children, this study evaluated the diagnostic value of Ultra in childhood tuberculosis using bronchoalveolar lavage fluid. The accuracy of Ultra was calculated by using bacteriologic results and clinical evidence as reference standards. Concordance between Ultra and Xpert MTB/RIF assays was assessed by using к coefficients. In total, 93 children with pulmonary tuberculosis and 128 children with respiratory tract infections were enrolled. The sensitivity of Ultra, in all pulmonary tuberculosis cases and in bacteriologically confirmed tuberculosis cases, was 70% and 91%, respectively. Ultra could detect <i>Mycobacterium tuberculosis</i> in 58% of cases with negative culture or acid-fast-staining results. The specificity of Ultra was 98%. There was no significant difference in sensitivity between samples with a volume ≤1 and >1 mL (66% vs 73%; <i>P</i> = .50; odds ratio [OR] = 0.71). Among 164 children for which Ultra and Xpert were simultaneously performed, the sensitivity was 80% and 67%, respectively, indicating good agreement (к = 0.84). An additional 6 children were identified as Ultra-positive but Xpert-negative. The positive rate decreased from 93% to 63% after 1 month (<i>P</i> = .01; OR = 0.12) and to 71% after 2 months (<i>P</i> = .03; OR = 0.18) of antituberculosis treatment. Ultra using bronchoalveolar lavage fluid has good sensitivity compared with bacteriologic tests and adds clinical value by assisting the rapid and accurate diagnosis of pulmonary tuberculosis in children.