Detection of Mycobacterium tuberculosis in tongue swab

Background: Sputum examination is the gold standard for the diagnosis of pulmonary tuberculosis. However, individuals particularly children, the aged, and immuno-compromised may not expectorate sputum due to some underlying conditions. Moreover, sputum produces infectious aerosols which exposes both the patients and care giver. It is also difficult to standardize sputum specimen for Mycobacterium tuberculosis. Therefore, the present study considered alternative specimen for pulmonary tuberculosis. Aim: To identify Mycobacterium tuberculosis in tongue swab. Methods: This is a prospective and cross-sectional laboratory-based study carried out in July-December 2022 on 384 tuberculosis patients attending health facilities in Karu, North central Nigeria. Using a multistage sampling technique, participants were added one at a time until the required sample size was gotten and analyzed via GeneXpert MTB/RIF. Performance of the tongue swab was compared to the combined reference standard of sputum XPERT. Results: The tongue swab XPERT ultra had a sensitivity of 78%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 97.4% relative to a sputum XPERT ultra reference standard. There were positive associations between the socio-demographic variables (age group, sex, family size, family type, marital status, religion, educational status, and occupation) and Mycobacterium tuberculosis infection. However, only the participant’s educational status (p=0.027) and occupation (p=0.05) had statistically significant difference. Conclusion: Tongue swab is an alternate specimen for sputum-based molecular diagnosis for Mycobacterium tuberculosis. The procedure is less invasive, easier, and non-aerosol producing efficient alternate approach for pulmonary tuberculosis.