Diagnostic performance of oral swabs for non-sputum based TB diagnosis in a TB/HIV endemic setting

Abstract

Objective We evaluated diagnostic performance of oral swab analysis (OSA) for tuberculosis (TB) in a high HIV/TB burden setting in Kenya. Methods In this cross-sectional study, buccal swabs and sputum were collected from 100 participants with suspected TB in outpatient clinics in Kenya at enrollment and subsequent morning visits. Buccal swabs underwent IS6110-targeted qPCR analysis. Sputum was evaluated by Xpert MTB/RIF (Xpert) and culture. Diagnostic performance of OSA for TB diagnosis was evaluated relative to a combined reference of sputum Xpert and culture. Results Among 100 participants, 54% were living with HIV (PLHIV). Twenty percent (20/100) of participants had confirmed TB (19/20 [95%] culture-positive, 17/20 [85%] Xpert-positive). Overall buccal swab sensitivity was 65.0% (95% CI 40.8–84.6%) vs. sputum Xpert/culture and 76.5% (95% CI 50.1–93.2%) vs. sputum Xpert alone. Specificity was 81.3% (95% CI 71.0–89.1%) and 81.9% (95% CI 72.0–89.5%) compared to sputum Xpert/culture and Xpert alone, respectively. Sensitivity among PLHIV (n = 54) with suspected TB was 83.3% (95% CI 35.9–99.6%) vs. sputum Xpert/culture and 100% (95% CI 47.8–100.0%) vs. sputum Xpert alone. Among participants with TB, mean OSA threshold quantitation cycle (Cq) value was lower (stronger signal) at subsequent morning compared to enrolment visit (33.4 SD ± 3.7 vs. 35.2 SD ± 2.9, p = 0.009). Conclusions In this pilot study, results confirm M. tuberculosis DNA is detectable in oral swabs including among PLHIV with fair diagnostic performance. Further work is needed to optimize OSA and evaluate its utility in diverse settings.

Advances in diagnostic tools for respiratory tract infections: from tuberculosis to COVID-19 – changing paradigms?

“…Samples must be collected taking medical condition into account, either from the upper (nasal/ throat specimens) or lower respiratory tract (bronchoalveolar lavage fluid, tracheal aspirate). Additionally, improved detection methods are making the use of new types of specimens possible and even saliva and oral mucosa may have a role to play in some situations [43][44][45][46]. But this is not true for all microorganisms, it depends on the pathogenesis and whether they are primary pathogens or potentially commensal.…”

What’s New in the Molecular Diagnosis of Childhood Tuberculosis?

“…4,6 Oral swabs taken from the buccal or tongue mucosa are being assessed for TB detection. 7 However, in children, optimization of commercial nucleic acid amplification tests (NAATs) is needed as the sensitivity of oral swabs is only 22% with Xpert Ultra. 8 Other sampling methods include the Pediatric Entero-string test, which retrieves gastric fluid via a nylon string coiled in a swallowed capsule for TB testing.…”

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

“…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.…”