Detection of pulmonary tuberculosis in children using the Xpert MTB/RIF Ultra assay on sputum: a multicenter study

Microbiological confirmation is rare in children with active tuberculosis; therefore, a more accurate test is needed to detect pulmonary tuberculosis in children. In this multicenter study, we evaluated the utility of the Xpert MTB/RIF Ultra (Ultra) on sputum, an assay recommended by the World Health Organization to test for childhood tuberculosis in high-burden settings. Children with symptoms suggestive of tuberculosis were enrolled at three hospitals in China and categorized as having active tuberculosis or nontuberculosis. The sensitivity and specificity of Ultra were 42.1% (48/114) and 99.0% (208/210), respectively. Using three MTB culture results as the reference, the sensitivity of Ultra in the subset of 38 children with culture-positive and 76 children with culture-negative was 68.4% (26/38) and 28.9% (22/76), respectively(p < 0.001). A single MTB culture combined with a single Ultra could detect 54 (54/114,47.4%) cases with active TB, while repeated MTB culture combined with a single Ultra detected 60 (60/114, 52.6%) cases with active TB(p = 0.427). Among 155 children (58 with TB and 97 with RTIs) simultaneously tested with the Ultra and Xpert MTB/RIF (Xpert), the sensitivity of the Xpert (24.1%, 14/58) was lower than that of the Ultra (41.4%, 24/58; p = 0.048). Eight children were found to have rifampin-resistant MTB strains. The Xpert MTB/RIF Ultra assay should be implemented to test for pulmonary tuberculosis in children to achieve higher confirmation rates.