In addition to mycobacterial culture, nucleic acid amplification tests are useful in confirming the diagnosis of TB disease in children. A Cochrane review of Xpert MTB/RIF for TB disease in children demonstrated a pooled sensitivity of 46-73% and a specificity of 98-99% for sputum, nasopharyngeal aspirates, gastric aspirates and stool as compared with mycobacterial culture in pulmonary TB. The same Cochrane review evaluated a small number of studies employing Xpert Ultra on sputum and reported a pooled sensitivity of 73% and specificity of 98% as compared with mycobacterial culture.39 The test characteristics of Xpert in CSF were similar at 54% sensitivity and 94% specificity, whereas the sensitivity increased to 90% in lymph node disease. Xpert Ultra assay on stool is being evaluated for diagnosing pulmonary TB in children and it appears promising in increasing the sensitivity, albeit at a cost of lower specificity.40
We strongly recommend that TB disease not be excluded in a child <10 years old with compatible clinical, epidemiological and/or radiographic features because of negative AFB cultures (good evidence).
We strongly recommend collecting three sputum samples for microbiological testing because they have a higher yield than a single sample (good evidence).
We strongly recommend sputum induction as an acceptable alternative to gastric aspirates in children <5 years old (good evidence).
We conditionally recommend that pediatric body fluid samples be submitted only for AFB culture when total sample volumes are ≤1 mL; if sample volumes are >1 ml, then both AFB culture and nucleic acid amplification tests should be requested to expedite diagnosis (poor evidence).
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