Diagnostic accuracy of sputum gene xpert MTB /RIF and stool gene xpert-ultra in children with pulmonary tuberculosis in a resource constraint country

Background: Diagnosis of tuberculosis in children remains a challenge especially in resource limited settings. This study aimed to determine the diagnostic accuracy of sputum Gene Xpert MTB/RIF and stool Xpert-Ultra for the diagnosis of PTB. Methods: This retrospective study was conducted in paediatric pulmonology ward of Bangabandhu Sheikh Mujib Medical University from March 2022 to December 2023.Consecuative 85 children aged 0-14 years with presumptive pulmonary tuberculosis (PTB) who provided both sputum and stool sample for GeneXpert and Xpert-Ultra respectively were included in the study. Diagnosis of PTB was confirmed by clinical, radiological, bacteriological or molecular evidence and taken as reference. Result: A total 119 children were enrolled; 85 of whom complete microbiological examination. PTB was diagnosed in 25 children. Of these 18(18/25) children was found positive in stool Xpert -Ultra and 6 children were tested positive by sputum /GA Gene Xpert MTB/RIF. All 6 positive sputum/GA samples were also positive on stool testing. The rate of concordance between stool and sputum was moderate with a kappa value of 0.441 (p<0.001). Overall sputum GeneXpert and stool Gene Xpert-Ultra showed Sensitivity of 24% and 72%, specificity of 100% and 100%, positive predicted value of 100% and 100%, negative predicted value of 75.95% and 89.55% and accuracy of 77.65% and 91.76% respectively. Conclusion: Stool gene xpert-ultra and sputum Gene Xpert both tests are highly specific for diagnosis of PTB. But sensitivity of stool Xpert-Ultra is more than the sputum Gene Xpert.