Oral swabs tested with Xpert MTB/RIF Ultra for diagnosis of pulmonary tuberculosis in children: a diagnostic accuracy study

Helen Cox, Lesley Workman, Lindy Bateman, Zoe Franckling-Smith, Margaretha Prins, Juaneta Luiz, Judi Van Heerden, Lemese Ah Tow Edries, Samantha Africa, Veronica Allen, Cynthia Baard, Widaad Zemanay, Mark P Nicol, Heather J Zar

Research output: Contribution to journalArticlepeer-review

2 Citations (Web of Science)

Abstract

BACKGROUND: Microbiological diagnosis of childhood tuberculosis may be difficult. Oral swabs are a potential non-invasive alternative to sputum for diagnosis.

METHODS: A prospective diagnostic accuracy study of oral swabs (buccal and tongue) for pulmonary tuberculosis (PTB) diagnosis in children (aged ≤15 years) in two South African hospital sites. Children with cough of any duration and either: a positive tuberculin skin test, TB contact, loss of weight or chest X-ray suggestive of PTB were enrolled. Two induced sputum specimens were tested with Xpert MTB/RIF (or Ultra) and liquid culture. Oral swabs were taken preceding sputum, frozen and later tested with Xpert MTB/RIF Ultra. Children were classified as microbiologically confirmed TB, Unconfirmed TB (received TB treatment) or unlikely TB according to NIH consensus definitions based on sputum microbiological results.

RESULTS: Among 291 participants (median age 32 [IQR 14-73] months), 57 (20%) were living with HIV and 87 (30%) were malnourished. 90 (31%) had confirmed PTB (six (7%) with rifampicin-resistant TB), 157 (54%) unconfirmed PTB and 44 (15%) unlikely TB. One oral swab was obtained from 126 (43%) participants (96 tongue, 30 buccal) and two swabs from 165 (57%) (110 tongue, 55 buccal). Sensitivity was low; 22% (95% CI 15-32) for all swabs combined (confirmed PTB as reference), but specificity was high (100%, 95% CI 91-100). The highest sensitivity was 33% (15-58) among participants living with HIV. Overall yield was 6.9% with one oral swab, and 7.2% with two.

CONCLUSIONS: Ultra on oral swabs provides poor yield for microbiologic PTB confirmation in children.

Original languageEnglish
Pages (from-to)2145-2152
Number of pages8
JournalClinical infectious diseases : an official publication of the Infectious Diseases Society of America
Volume75
Issue number12
DOIs
Publication statusPublished - 19 Dec 2022

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