Evaluation of stool as an alternative specimen for the diagnosis of paediatric pulmonary tuberculosis: a cross-sectional study

Diagnosis of paediatric pulmonary tuberculosis (PTB) continues to be a major challenge due to the inability to expectorate and paucibacillary nature of the disease. In endemic settings, the diagnosis of paediatric PTB depends mainly on clinical and radiological features as gastric aspirate (GA) is an unpleasant procedure and requires expertise as well as hospital admission. This hinders microbiological diagnosis and resistance detection. This study aims to evaluate the use of a less invasive, alternative specimen like stool for the microbiological confirmation of paediatric PTB. Gastric aspirate or induced sputum (IS) and stool samples (at least 2 gm) samples were collected from children of age <14 years old with suspected PTB admitted in the paediatric department. IS/GA was tested as per National Tuberculosis Elimination Programme protocol by Xpert MTB/RIF-Ultra assay. Processing of stool samples was standardized and appropriate protocol followed for Xpert MTB/Rif-Ultra assay. A total of 104 pairs of samples were tested by Xpert-Ultra assay. Eighteen of 104 GA/IS samples were positive; of which stool samples were positive in 15 cases. The bacterial load in 2 samples were low and very low in one. All GA/IS with medium and high bacterial load were detected by Stool Xpert-Ultra assay, and stool Xpert assay was positive in five GA/IS Xpert-Ultra negative samples. Stool can be used as an alternative sample for the diagnosis of paediatric PTB.