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

Abstract

Objectives: Our study 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 of China. Methods: Children with presumptive TB were enrolled in two hospitals in Sichuan Province (July 2019–Oct 2020). Because of the unavailability of sputum for etiological testing, gastric samples were aspirated and tested by bacterial culture, acid-fast bacillus microscopy, and Ultra. Stool samples were tested simultaneously using Ultra and Xpert. Results: In total, 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) tests 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 tests are appropriate for bacteriological TB confirmation.

Keywords

• tuberculosis
• child
• diagnosis
• stool