Use of stool swabs in molecular transport media increases access to Xpert Ultra testing for TB in children

Abstract

SETTING: Tertiary level hospital in Lusaka, Zambia.OBJECTIVE: To measure concordance between Xpert® MTB/RIF Ultra (Ultra) results of stool with and without transport media, and compare Ultra results from the two stool processing methods to Ultra and culture results using gastric aspirates (GA).DESIGN: This was a cross-sectional study collecting stool and GA from children 0–5 years presenting with signs and symptoms of TB. Stool was processed for Ultra testing by two methods: the Simple-One-Step (SOS) on an aliquot of stool and PrimeStore® MTM Molecular Transport Medium (PS-MTM) using a stool swab.RESULTS: A total of 114 children (median age: 17 months, IQR 7–30) provided both a stool and a GA sample. Stool Ultra results processed using the PS-MTM method showed high concordance with stool Ultra results processed by the SOS method, with only 1/114 discordant results. Concordance with GA Ultra was high as well, as 9/13 Mycobacterium tuberculosis (MTB) cases detected were identified by all three methods.CONCLUSION: Ultra results from stool swabs collected using PS-MTM were equivalent to results from stool using the SOS method and GA. Given that PS-MTM inactivates MTB and stabilises DNA without cold chain, using it for stool has the potential to increase access to a TB diagnosis for children in underserved areas.