TB-Speed to present
a new publication in “Tuberculosis” (ScienceDirect, Elsevier)
on newly developed and simplified stool testing method
for TB diagnosis in high burden settings.
LABORATORY DEVELOPMENT OF A SIMPLE STOOL SAMPLE PROCESSING METHOD DIAGNOSIS OF PEDIATRIC TUBERCULOSIS USING XPERT ULTRA
Stool samples are alternatives to respiratory samples for bacteriological confirmation of childhood tuberculosis
but require intensive laboratory processing before molecular testing to remove PCR inhibitors and debris. We
aimed to develop a centrifuge-free processing method for use in resource-limited settings based on a sucroseflotation
method that showed good sensitivity for childhood tuberculosis diagnosis.
In an in vitro study using Xpert MTB/RIF Ultra on stool samples spiked with defined bacterial concentrations of
Mycobacterium tuberculosis (MTB), we compared different simplification parameters to the reference sucroseflotation
method. Best methods were selected based on the rate of invalid/error results and on sensitivity,
compared to the reference method on stools spiked at 103 colony forming units (CFU)/g MTB. For final selection,
we tested the best parameter combinations at 102 CFU/g. Out of 13 different parameter combinations, three were
tested at 102 CFU/g. The best combination used 0.5 g stool, manual shaking, no filtration, 30-min sedimentation,
and a 1:3.6 dilution ratio. This method gave 10% invalid/error results and a sensitivity of 70% vs 63% at 103
CFU/g and 53% vs 58% at 102 CFU/g compared to the reference method.
This pre-clinical study was able to develop a centrifuge-free processing method to facilitate stool Xpert Ultra
Manon Lounnas, Abibatou Diack, Mark P.Nicol, Sara Eyangoh, Eric Wobudeya, Olivier Marcy, Sylvain Godreuil, Maryline Bonnet