Accuracy of Tongue Swab Testing Using Xpert MTB-RIF Ultra for Tuberculosis Diagnosis

Abstract

Tongue dorsum swabs have shown promise as alternatives to sputum for detecting Mycobacterium tuberculosis (MTB) in patients with pulmonary tuberculosis (TB). Some of the most encouraging results have come from studies that used manual quantitative PCR (qPCR) to analyze swabs.

Complementary Nonsputum Diagnostic Testing for Tuberculosis in People with HIV Using Oral Swab PCR and Urine Lipoarabinomannan Detection

“…Both reserved and duplicate samples (total N=18) were paired with manual OSA data. Samples were tested by Xpert Ultra by using either of two methods described elsewhere (22), depending on whether they were reserve or duplicate. Briefly, in one method ("boil method"), 200 µL)halfsamples, which were previously boiled and stored frozen, were thawed and received 2.2 mL TE buffer.…”

“…Duplicate samples, which were not previously boiled, were processed by the "single swab SR method" described in reference (22). These 0.5-mL samples were thawed at ambient temperature for 30 min, then supplemented with 0.3 mL TE and 1.6 mL of Cepheid Sample Reagent (SR).…”

“…In search of an alternative non-sputum sample type, we and others have shown that MTB DNA can be detected by oral swab analysis (OSA) (13)(14)(15)(16)(17)(18)(19)(20)(21)(22). In OSA, the dorsum of the tongue is brushed with a sterile swab, and the collected material is tested for MTB DNA.…”

Feasibility and Sensitivity of Saliva GeneXpert MTB/RIF Ultra for Tuberculosis Diagnosis in Adults in Uganda

“…Using a different sampling technique, oral swab analysis, Wood and colleagues confirmed that TB is indeed present in the oral cavity when they reported that nylon swabs of the tongue and mouth assayed via insertion sequence IS 6110 PCR detected 18 of 20 (90%) South African patients with TB confirmed via the pre-Ultra GeneXpert MTB/RIF assay on sputum ( 7 ). A larger and more recent study from Uganda of oral swab analysis with Xpert Ultra in 183 adults with possible TB showed a slightly lower sensitivity of 78% (95% CI, 64 to 88%) relative to relative to a sputum reference standard and an outstanding specificity of 100% (95% CI, 97 to 100%) ( 8 ). Saliva is also now widely used for molecular diagnosis of COVID-19, where it has high sensitivity, even among patients without symptoms ( 9 ).…”

Preferences of health care workers using tongue swabs for tuberculosis diagnosis during COVID-19

“…[1][2][3] We and others have shown that MTB DNA is deposited on the oral epithelium during active TB, and can be detected by oral swab analysis (OSA). [4][5][6][7][8][9][10][11][12][13][14][15] In OSA, the dorsum of the tongue is brushed with a sterile swab. The swab head with collected material is deposited into a tube for MTB DNA detection by nucleic acid amplification testing (NAAT).…”