Stool Xpert MTB/RIF as a possible diagnostic alternative to sputum in Africa: a systematic review and meta-analysis

Abstract

IntroductionWorldwide, COVID-19 pandemic lead to a large fall in the number of newly reported TB cases. In sub-Saharan Africa, microbiological diagnosis of TB is generally based on smear microscopy and Xpert MTB/RIF on sputum samples, but good quality sputum samples are often difficult to obtain, leading clinicians to rely on more invasive procedures for diagnosis. Aim of this study was to investigate pooled sensitivity and specificity of Xpert MTB/RIF on stool samples compared to respiratory microbiological reference standards in African countries.MethodsFour investigators independently searched PubMed, SCOPUS, and Web of Science until 12th October 2022, then screened titles and abstracts of all potentially eligible articles. The authors applied the eligibility criteria, considered the full texts. All the studies reported the data regarding true positive (TP), true negative (TN), false positive (FP) and false negative (FN). Risk of bias and applicability concerns were assessed with the Quadas-2 tool.Resultsoverall, among 130 papers initially screened, we evaluated 47 works, finally including 13 papers for a total of 2,352 participants, mainly children. The mean percentage of females was 49.6%, whilst the mean percentage of patients reporting HIV was 27.7%. Pooled sensitivity for Xpert MTB/RIF assay for detecting pulmonary tuberculosis was 68.2% (95%CI: 61.1–74.7%) even if characterized by a high heterogeneity (I2=53.7%). Specificity was almost 100% (99%, 95%CI: 97–100%; I2 = 45.7%). When divided for reference standard, in the six studies using sputum and nasogastric aspirate the accuracy was optimal (AUC = 0.99, SE = 0.02), whilst in the studies using only sputum for tuberculosis detection the AUC was 0.85 (with a SE = 0.16). The most common source of bias was exclusion of enrolled patients in the analysis.ConclusionsOur study confirms that, in Africa, stool Xpert MTB/RIF may be a useful rule-in test for children above and below 5 years of age under evaluation for pulmonary tuberculosis. Sensitivity increased substantially when using both sputum and nasogastric aspirate as reference samples.

Accuracy of Nanopore Sequencing as a Diagnostic Assay for Pulmonary Tuberculosis versus Smear, Culture and Xpert MTB/RIF: A Head-to-Head Comparison

“…Hence, in clinical practice, sequencing results should be strictly interpreted based on patient clinical manifestations in combination with imaging signatures and other conventional clinical microbiological test results. Fifth, it has been shown that stool Xpert MTB/RIF may be a useful rule-in test for children above and below 5 years of age under evaluation for PTB [ 32 ], which is of great significance for patients from whom good quality sputum samples are difficult to obtain. However, the diagnostic value of nanopore sequencing in non-respiratory samples for TB was not explored in this study, which may be our future research direction.…”

Successful Management, in a Low-Resource Setting, of Disseminated Tuberculosis in a 3-Year Old Boy: A Case Report

“…It is thus essential to, on the one hand, to strengthen existing structures and, on the other, to find alternative solutions. In this regard, recent evidence suggests the possible role of Stool Xpert MTB/RIF on stool samples, especially in sub-Saharan settings, although its diagnostic accuracy and cost-effectiveness are still under investigation [ 12 ]. Despite possible future solutions, it is essential to support and collaborate in defeating TB, not only for low-income countries but also in terms of global and globalised health.…”