Biography
Dr Simon Mendelsohn is an investigator at the South African Tuberculosis Vaccine Initiative (SATVI), University of Cape Town, with clinical experience in TB and HIV, including work with Médecins Sans Frontières implementing HIV and TB programmes in Malawi prisons. He has contributed as an investigator on over 30 TB vaccine and therapeutic clinical trials, as well as diagnostic observational studies. His current research focuses on novel, non-sputum tests for detecting persistent Mycobacterium tuberculosis infection, pre-symptomatic TB disease, and biomarker-guided strategies for TB preventive and curative therapy.
Key Impacts
Oral rinse outperforms facemask capture for non-sputum diagnosis of pulmonary TB
Non-sputum-based rapid diagnostics are urgently needed to test both symptomatic and asymptomatic people with tuberculosis (TB) who are missed by current sputum-based tools. We performed head-to-head comparison of two non-sputum sampling approaches, oral rinse and facemask capture, for diagnosis of pulmonary TB.Methods: We recruited HIV-negative adults (≥18 years) with newly-diagnosed, bacteriologically-confirmed pulmonary TB and healthy controls in Worcester, South Africa (October 2024-May 2025). TB participants were excluded if treated for >1 day or previously diagnosed within 2 years. Facemasks fitted with polyvinyl alcohol (PVA) patches were worn for ≥1 hour. Thereafter, a patch was dissolved in 2mL sterile water. Oral rinse samples were obtained using a 1-minute rinse with 5mL sterile water. Both sample types were mixed with Xpert SR buffer (0.75mL:1.5mL ratio) and tested at the clinical field site laboratory with Xpert Ultra. Thereafter, sputum samples were collected. TB cases were both sputum MGIT culture and Ultra (excluding trace) positive.Results: Among symptomatic clinic attendees with TB (n=25), oral rinse sensitivity was 64.0% (95%CI: 44.5-80.0) vs. 32.0% (95%CI: 17.2-52.0) for facemask capture (McNemar p=0.0047). Specificity among 86 healthy controls was 100% (95%CI: 95.7-100) for both methods. In 6 asymptomatic TB cases identified through community screening, oral rinse sensitivity was 33.3% (95%CI: 9.7-70.0) vs. 16.7% (95%CI: 3.0-56.0) for facemask capture. Sensitivity of oral rinse and facemask capture among participants with sputum semi-quantitative Xpert Ultra graded medium/high (n=20) was 85.0% (95%CI: 64.0-95.0) and 45.0% (95%CI: 25.8-66.0), respectively; and for those graded very-low/low (n=11), 18.2% (95%CI: 5.1-48.0) and 0.0% (95%CI: 0.0-26.0), respectively.Conclusions: Oral rinse sampling was more sensitive than facemask capture for pulmonary TB diagnosis by Xpert Ultra. Sensitivity appears higher among symptomatic individuals and those with higher sputum bacillary burden. These findings support further optimisation of oral rinse as a promising non-sputum diagnostic alternative for pulmonary TB.
Source: Conference 2024