Stool-based Xpert MTB/RIF Ultra assay as a tool for detecting pulmonary tuberculosis in children with abnormal chest imaging: A prospective cohort study - 19/01/21
, Shui-hua Lu a, e, f, ⁎ Highlights |
• | Young children with pulmonary TB swallow sputum, in which Mycobacteria. tuberculosis could be detected from stool samples. Detecting pediatric pulmonary tuberculosis by stool Xpert MTB/RIF (Xpert) assay was reported, but the sensitivity was relatively lower than respiratory tract samples (RTS) and inconsistent in publications. The Xpert Ultra assay (Ultra) was designed to improve the sensitivity of Xpert, and was validated in previous studies. This study aimed to evaluate the value of stool-based Ultra assay in paediatric pulmonary TB (PTB). To overcome the bias introduced from heterogeneity in inclusion criteria, sample processing, and clinical definition, researchers performed a head-to-head comparison between assays, and the results were parallelly assessed against culture and composite reference standard. |
• | Children under 5 years old were enrolled and well evaluated in this study. These populations are more likely to benefit from this technique but rarely evaluated. According to this study, the stool-based Xpert MTB/RIF Ultra test showed substantial agreement with respiratory tract sample test for PTB. This test may take the place of respiratory tests in resource-limited context, particularly in young children not able to expectorate. |
• | The stool-based molecular tests were promising for the detection of PTB. However, this study unveiled some limitations of this technique, including more trace positive and potential false positive, which are less likely to appear in Xpert test. Impacts from these limitations should be assessed in further studies. |
Summary |
Objectives |
To evaluate the diagnostic efficacy of stool-based Xpert MTB/RIF Ultra assay versus other assays for the detection of paediatric pulmonary tuberculosis (PTB).
Methods |
A prospective head-to-head comparative study was conducted from Dec 2017 to May 2019 in Shanghai Public Health Clinical Centre. Samples were collected from children (< 15 years) with abnormal chest imaging (X-ray or CT scan) results for the following tests: Ultra on stool sample (Ultra-Stool), Ultra on respiratory tract sample (Ultra-RTS), Xpert MTB/RIF assay (Xpert) on RTS (Xpert-RTS), acid-fast bacilli smear on RTS (AFB-RTS), and Mycobacterium tuberculosis (Mtb) culture on RTS (Culture-RTS). The results were compared with a composite reference standard.
Results |
A total of 126 cases with paired results were analysed. Against a composite reference standard, Ultra-RTS demonstrated the highest sensitivity (52%) and specificity (100%). Ultra-Stool showed 84.1% concordance with Ultra-RTS, demonstrating 45.5% sensitivity and 94.7% specificity (kappa = 0.65, 95% CI= 0.51–0.79). The sensitivity of Ultra-Stool was similar to Mtb culture (45.5%, p = 1.000) and higher than AFB-RTS (27.3%, p < 0.05). Assay positivity was associated with age and infiltration range in chest imaging.
Conclusions |
When RTS is difficult to obtain, stool sample-based Ultra is a comparable alternative.
Le texte complet de cet article est disponible en PDF.Keywords : Xpert MTB/RIF Ultra, Tuberculosis, Children, Trace-positive, Stool
Plan
Vol 82 - N° 1
P. 84-89 - janvier 2021 Retour au numéro
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