Wood Rachel C, Luabeya Angelique K, Dragovich Rane B, Olson Alaina M, Lochner Katherine A, Weigel Kris M, Codsi Renée, Mulenga Humphrey, de Vos Margaretha, Kohli Mikashmi, Penn-Nicholson Adam, Hatherill Mark, Cangelosi Gerard A
University of Washington, Department of Environmental and Occupational Health Sciences, Seattle, United States of America.
South African Tuberculosis Vaccine Initiative, Institute of Infectious Disease & Molecular Medicine and Department of Pathology, University of Cape Town, Cape Town, South Africa.
medRxiv. 2023 Oct 11:2023.10.10.23296833. doi: 10.1101/2023.10.10.23296833.
Tongue dorsum swabbing is a potential alternative to sputum collection for tuberculosis (TB) testing. Previous studies showed that Cepheid Xpert MTB/RIF Ultra (Xpert Ultra) can detect (MTB) DNA in tongue swabs stored in buffer, with 72% sensitivity and 100% specificity relative to a sputum microbiological reference standard (sputum MRS). The present study evaluated a more convenient sample collection protocol (dry swab storage), combined with streamlined sample processing protocols, for side-by-side analysis using two commercial TB diagnostic tests: Xpert Ultra and Molbio Truenat MTB Ultima (MTB Ultima). Copan FLOQSwabs were self-collected, or collected by study workers, from 321 participants in Western Cape, South Africa. All participants had symptoms suggestive of TB, and 245 of them had sputum MRS-confirmed TB (by sputum culture and/or Xpert Ultra). One tongue swab per participant was tested on Xpert Ultra and another tongue swab was tested with MTB Ultima. Xpert Ultra was 75.4% sensitive and 100% specific, and MTB Ultima was 71.6% sensitive and 96.9% specific, relative to sputum MRS. When sample lysates that were false-negative by MTB Ultima were frozen, thawed, and re-tested, MTB Ultima sensitivity rose to 79.1%. Both tests were more sensitive with swabs from participants with higher sputum Xpert semi-quantitative results. The protocol for Xpert Ultra enabled fast and easy testing of dry-stored swabs with no loss of accuracy relative to previous methods. MTB Ultima testing of dry-stored swabs exhibited comparable performance to Xpert Ultra. These results further support tongue swabs as easy-to-collect samples for high-throughput TB testing.
舌背拭子采样是结核病（TB）检测中痰液采集的一种潜在替代方法。先前的研究表明，赛沛Xpert MTB/RIF Ultra（Xpert Ultra）能够检测缓冲液中保存的舌拭子中的结核分枝杆菌（MTB）DNA，相对于痰液微生物学参考标准（痰液MRS），其灵敏度为72%，特异性为100%。本研究评估了一种更便捷的样本采集方案（干拭子保存），并结合简化的样本处理方案，使用两种商用结核病诊断检测方法进行并行分析：Xpert Ultra和Molbio Truenat MTB Ultima（MTB Ultima）。Copan FLOQSwabs拭子由南非西开普省的321名参与者自行采集或由研究人员采集。所有参与者均有提示结核病的症状，其中245人经痰液MRS确诊为结核病（通过痰液培养和/或Xpert Ultra检测）。每位参与者的一支舌拭子用Xpert Ultra检测，另一支舌拭子用MTB Ultima检测。相对于痰液MRS，Xpert Ultra的灵敏度为75.4%，特异性为100%；MTB Ultima的灵敏度为71.6%，特异性为96.9%。当MTB Ultima检测为假阴性的样本裂解物经冷冻、解冻后重新检测时，MTB Ultima的灵敏度升至79.1%。对于痰液Xpert半定量结果较高的参与者的拭子，两种检测方法的灵敏度均更高。Xpert Ultra的检测方案能够对干保存拭子进行快速、简便的检测，相对于之前的方法，准确性没有损失。对干保存拭子进行MTB Ultima检测的性能与Xpert Ultra相当。这些结果进一步支持舌拭子作为易于采集的样本用于高通量结核病检测。
