Use of Xpert MTB/RIF Ultra assay on stool and gastric aspirate samples to diagnose pulmonary tuberculosis in children in a high-tuberculosis burden but resource-limited area of China: Diagnosis of Childhood TB using Stool.

Abstract Objectives We analyzed the performance of Xpert MTB/RIF Ultra (Ultra) on stool and gastric aspirate (GA) samples for the diagnosis of pediatric pulmonary tuberculosis (TB) caused by Mycobacterium tuberculosis in a high burden area in China. Methods Children with presumptive TB were enrolled in two hospitals in Sichuan Province (July 2019–Oct 2020). Because of the unavailable sputum for etiological tests, GA samples were aspirated and tested by bacterial culture, acid-fast bacillus microscopy and Ultra. Stool samples were tested simultaneously using Ultra and Xpert. Results Finally, 141 children with active TB and 34 with non-TB respiratory tract infections were enrolled. Ultra-stool (60.3%, 85/141) and Ultra-GA (52.5%, 74/141) were similarly sensitive (P=0.187). Among the subset of 48 children with confirmed TB, Ultra testing was equally sensitive on stool and GA samples (85.4%, 41/48). The agreement between Ultra-stool and Ultra-GA was moderate in children with active TB (kappa value = 0.527). After integrating Ultra-GA and Ultra-stool outcomes, 70.9% (100/141) of the children were considered to have confirmed TB. The specificities of Ultra-stool and Ultra-GA were 97.1% (33/34) and 100% (34/34), respectively (P=0.314). Conclusions In children, stools can be used as alternative samples to GAs for Ultra tests. Stool- and GA-based Ultra are appropriate tests for bacteriological TB confirmation.