TABLE 2Description of WHO-approved respiratory samples for the diagnosis of PTB Specimen Procedure Advantages/disadvantages Caregiver acceptability Diagnostic accuracy: sensitivity/specificity (certainty of evidence) Expectorated sputum Expectoration of sputum without prior nebulisation Advantages: low cost noninvasive Disadvantages: not feasible in young children (8 years) High Xpert MTB/RIF: 0.65/0.99 (moderate) Xpert MTB/RIF Ultra: 0.73 (low)/0.97 (high) Induced sputum Expectoration of sputum (either spontaneous or after nasopharyngeal aspirate) following hypertonic saline nebulisation Advantages: noninvasive (if followed by expectorated sputum) Disadvantages: requires equipment, trained personnel, electricity and consumables aerosolised transmission risk Moderate Xpert MTB/RIF: 0.65/0.99 (moderate) Xpert MTB/RIF Ultra: 0.73 (low)/0.97 (high) Nasopharyngeal aspirate Nasopharyngeal suctioning using a sterile catheter with a mucus trap/suctioning device while child in the supine position either directly or after induced sputum Advantages: feasible in young children less invasive than gastric aspirate Disadvantages: invasive requires equipment, electricity, consumables, trained personnel and 2 h fasting high level of discomfort aerosolised transmission risk Moderate Xpert MTB/RIF: 0.46 (moderate)/ 1.0 (high) Xpert MTB/RIF Ultra: 0.46 (very low)/0.98 (low) Gastric aspirate Nasogastric aspiration of gastric juice (containing swallowed sputum) first thing in morning Gastric lavage: instillation of solution to“wash off”and recover sputum adhered to stomach wall if gastric aspirate 5 mL Advantages: feasible in young children common procedure for nurses Disadvantages: invasive high level of discomfort requires consumables, trained personnel and 4 h fasting Low Xpert MTB/RIF: 0.73 (very low)/0.98 (low) Xpert MTB/RIF Ultra: 0.64/0.95 (moderate) Stool Sampling from random stool, which can detect swallowed sputum from the respiratory system Advantages: noninvasive Disadvantages: requires additional laboratory processing must wait for bowel movement High Xpert MTB/RIF: 0.70 (low)/0.98 (high) Xpert MTB/RIF Ultra: 0.53/0.98 (moderate) Reproduced and modified from [27] with permission. https://doi.org/10.1183/2312508X.10025322 221 CHILDREN AND ADOLESCENTS |E. LÓPEZ-VARELA ET AL.