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 XpertVR 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 PrimeStoreVR 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.