Can Tongue Swabs Improve Tuberculosis Detection in Children?
Tuberculosis (TB) remains one of the top 10 causes of death worldwide. Childhood TB is especially difficult to diagnose due to paucibacillary disease and limitations of current tests. Could sampling the oral cavity provide a better approach? Recent research indicates promise for detecting Mycobacterium tuberculosis (Mtb) DNA in adult oral swabs.
Can we detect TB in children from tongue swabs?
Standard tests like sputum smears have poor sensitivity in kids. More invasive sampling like gastric lavage is uncomfortable. The study showed promise in detecting Mycobacterium tuberculosis (Mtb) DNA from adult oral swabs. This paper by Ealand et al. investigated using tongue swabs to detect TB in young hospitalized children.
What methods did the researchers use?
The authors collected 35 tongue swabs from children ≤5 years old, with 26 clinically diagnosed with TB and 9 with other lower respiratory tract infections (LRTI). They used a combination of quantitative PCR, spoligotyping, auramine microscopy, and culture to analyze the samples. PCR targeted insertion element IS6110 specific for Mtb complex. Spoligotyping detects strain types. Microscopy visualizes acid-fast bacilli. Culture detects viable bacteria.
What were the key findings?
Mtb DNA was detected by PCR in 11/26 TB cases but none of the LRTIs, indicating good specificity. 5/11 PCR+ samples had identifiable Mtb genotype by spoligotyping. Microscopy revealed acid-fast bacilli in 73% of TB cases, although mostly scanty amounts. No samples grew in culture, but intact bacilli were visible on smears. 21/26 clinically diagnosed TB cases were positive by ≥1 test.
What is the significance of this study?
This preliminary data provides compelling evidence for using non-invasive tongue swabs to improve TB diagnosis in children. Combining PCR, spoligotyping and microscopy on the swabs enhanced detection of Mtb complex bacteria and their DNA, especially compared to standard sputum tests. The authors conclude tongue swabs could be a useful alternative clinical sample for pediatric TB detection.
Further validation is needed given the small sample size here. But tongue swabs clearly have potential to provide a better diagnostic approach in children that is safer, more comfortable and child-friendly.
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Reference
Ealand C, Peters J, Jacobs O, Sewcharran A, Ghoor A, Golub J, Brahmbhatt H, Martinson N, Dangor Z, Lala SG, Kana B. Detection of Mycobacterium tuberculosis Complex Bacilli and Nucleic Acids From Tongue Swabs in Young, Hospitalized Children. Front Cell Infect Microbiol. 2021 Jun 14;11:696379. doi: 10.3389/fcimb.2021.696379. PMID: 34195103; PMCID: PMC8238041.
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