A Test for More Accurate Diagnosis of Pulmonary Tuberculosis

Abstract

Objectives: Xpert Mycobacterium tuberculosis 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.

Methods: 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.

Results: 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 Mycobacterium tuberculosis 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%; P = .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 (P = .01; OR = 0.12) and to 71% after 2 months (P = .03; OR = 0.18) of antituberculosis treatment.

Conclusions: 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.