Differentially Culturable Tubercle Bacteria: The missing link in TB Transmission?

1项目概要 2迄今为止，大多数结核病（TB）传播研究严重依赖于细菌的标准培养。 3从痰液中确定传播环节。这种方法的基本假设是， 4种培养方法可回收所有传播菌株。此外，未报告结核病的个人 5症状和痰培养阴性者被认为是非传染性的。这些 6个假设构成了当代结核病传播研究的基本前提。我们的描述 痰液中7种差异培养结核杆菌（DCTB），无法在标准培养物中生长， 8出现在补充有培养滤液（CF）的液体培养基中，挑战了普遍的假设， 对结核病传播的9个重要影响痰中DCTB的存在表明标准培养 10未能检测到与TB传播相关的细菌群体的显著比例。 11我们假设，对痰液进行DCTB检测将增加细菌数量 12回收，并将确定更多的细菌基因型相比，标准培养。这将有利于 13建立标准文化所忽略的传播联系。在索引结核病患者中，我们将 首先通过对标准痰液中出现的细菌基因型的深入表征来探索这一点 与从DCTB测定中出现的那些相比。细菌菌株的基因型将是 16个通过全基因组测序鉴定。我们将重点关注对药物敏感和对利福平单一耐药的结核病， 17后者的传播被确定为结核病流行国家新出现的公共卫生危机。以下 18指数患者的表征，我们将使用DCTB测定来增加细菌产量和基因型多样性 19例从家庭接触者的痰中痊愈。然后，我们将使用传输推理建模， 20个在家庭中建立了新的传播联系，这些联系被DCTB检测发现，但没有使用 21标准培养。此外，我们将测试新型荧光探针的效用，标记活分枝杆菌， 22一种研究家庭接触者痰液中极低细菌载量的替代方法， DCTB检测23例。 24我们预计，这种方法将为家庭中的结核病传播提供新的见解， 25允许有效地针对这种环境采取传播阻断干预措施。此外，应用 26种DCTB检测结合新兴分离株的深入全基因组测序将验证新的 研究结核病传播的27种方法

1 PROJECT SUMMARY 2 Most tuberculosis (TB) TB transmission studies to date have relied heavily on the standard culture of bacteria 3 from sputum to determine transmission links. The underlying assumption with this approach is that standard 4 culture methods allow for the recovery of all transmitted strains. Furthermore, individuals not reporting TB 5 symptoms and those with negative sputum cultures have been presumed to be non-infectious. These 6 assumptions form the fundamental premise of the contemporary study of TB transmission. Our description of 7 differentially culturable tubercle bacilli (DCTB) in sputum that are unable to grow in standard culture and only 8 emerge in liquid media supplemented with culture filtrate (CF) challenge prevailing assumptions and have 9 important implications for TB transmission. The presence of DCTB in sputum suggests that standard culture 10 fails to detect significant proportions of bacterial populations that are relevant to TB transmission. 11 We hypothesize that DCTB assays on sputum will allow for an increased yield in the quantum of bacteria 12 recovered and will identify more bacterial genotypes when compared to standard culture. This will facilitate the 13 establishment of transmission links that would be missed by standard culture. In index TB patients, we will 14 explore this, first through an in-depth characterization of bacterial genotypes that emerge in standard sputum 15 culture compared to those emerging from DCTB assays. The genotypes of the bacterial strains will be 16 identified by whole genome sequencing. We will focus both on drug sensitive and rifampin monoresistant TB, 17 the transmission of the latter identified as an emerging public health crisis in TB endemic countries. Following 18 characterization of index patients, we will use DCTB assays to increase bacterial yield and genotypic diversity 19 recovered from the sputum of household contacts. We will then use transmission inference modelling to 20 establish new transmission links in the household that were detected by DCTB assays but missed using 21 standard culture. In addition, we will test the utility of novel fluorogenic probes that label viable mycobacteria as 22 an alternate method to study very low bacterial loads in sputum of household contacts that may not be 23 detected with DCTB assays. 24 We anticipate that this approach will provide novel insight on TB transmission in the household, thereby 25 allowing for effective targeting of transmission blocking interventions to this setting. In addition, the application 26 of DCTB assays combined with in-depth whole genome sequencing of emerging isolates will validate new 27 methods to study transmission of TB.