Molecular detection of Mycobacterium tuberculosis from buccal swabs among adult in Peru

Annelies W Mesman,Zibiao Zhang,Juan Aliaga,Nira R Pollock,Rebecca C Holmberg,Milagros Mendoza,Martín Soto,Molly F Franke,Roger I Calderon,Julia Coit,Leonid Lecca

doi:10.1038/s41598-020-79297-9

Abstract

Tuberculosis (TB) diagnosis relies on a sputum sample, which cannot be easily obtained from all symptomatic patients. Mycobacterium tuberculosis DNA can be detected from oral swabs, a noninvasive, safe alternative sample type; however, reported sensitivities have been variable and likely depend on sample collection, processing procedures and host characteristics. We analyzed three buccal swab samples from 123 adults with culture-confirmed TB in Lima, Peru. We compared the sensitivity and specificity of two sample collection devices (OmniSwab and EasiCollect FTA cards) and examined factors associated with detection. DNA was extracted with a commercially available kit and detected via real-time PCR IS6110 amplification. Overall sensitivity for buccal samples was 51% (95% Confidence Interval [CI] 42–60%). Specificity from a single sample among healthy controls was 96.7% (95% CI 83–99.9%). Positive sputum smear and cavitary disease, correlates of disease burden, were associated with detection via buccal swab. Although we observed higher sensitivities with the Omniswab samples, this appeared to be due primarily to differences in patient characteristics (e.g., cavitary disease). Overall, our findings support the potential for a buccal sample-based TB assay. Future work should focus on assay optimization and streamlining the assay workflow.

Highlights

Tuberculosis (TB) diagnosis relies on a sputum sample, which cannot be obtained from all symptomatic patients
Prompt diagnosis and treatment initiation are critical to TB care and control, but are often limited for patients who are unable to produce a sputum sample for microbiological confirmation of Mycobacterium tuberculosis (Mtb)[2,3]
We found a sensitivity of 58% among patients with smear-positive TB, this was highest, 64%, among patients who had all samples collected with OmniSwab

Summary

Introduction

Tuberculosis (TB) diagnosis relies on a sputum sample, which cannot be obtained from all symptomatic patients. Because obtaining a sputum sample is not possible in all patients, studies have sought to identify alternative sample types for molecular detection of TB disease, including oral s wabs[4,5,6,7]. This specimen is advantageous because collection is non-invasive and reduces transmission risk to health care workers as it produces no aerosols. We report detection of Mtb from buccal samples collected from adults with culture-confirmed TB disease in Lima, Peru. We examined patient and sample collection factors associated with detection

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