Noninvasive detection of Tuberculosis by Oral Swab Analysis

Diagnostic tests for tuberculosis (TB) usually require collection of sputum, a viscous material derived from human airways. Sputum can be difficult and hazardous to collect and challenging to process in the laboratory. Oral swabs have been proposed as alternative sample types that are noninvasive and easy to collect. The use of oral swabs for TB detection was originally created in my lab for use with nonhuman primates in biomedical research settings and in the wild. This latest study evaluated the biological feasibility of oral swab analysis (OSA) for the diagnosis of TB. Swabs were tested from South African adult subjects, including sputum
GeneXpert MTB/RIF (GeneXpert)-confirmed TB patients (n 138), sputum GeneXpert-negative but culture-positive TB patients (n 10), ill non-TB patients (n 37), and QuantiFERON-negative controls (n 34). Swabs were analyzed by using a manual, nonnested quantitative PCR (qPCR) targeting IS6110. In a two-phase study, tongue swabs (two per subject) exhibited a combined sensitivity of 92.8% relative to sputum GeneXpert. Relative to all laboratory-diagnosed TB, the diagnostic yields of sputum GeneXpert (1 sample per subject) and OSA (2 samples per subject) were identical at 49/59 (83.1%) each. The specificity of the OSA was 91.5%. The use of oral swabs to detect TB is highly sensitive and specific.