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

可差异培养的结核菌：结核病传播中缺失的环节？

• 批准号: 10238034
• 负责人: Bavesh Davandra Kana
• 金额: $ 98.24万
• 依托单位: WITS HEALTH CONSORTIUM (PTY), LTD
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10238034
• 关键词: Address; Adopted; Affect; Bacillus; Bacteria; Biological Assay; Country; Culture Techniques; Data; Detection; Development; Disease; Disease Resistance; Drug resistance; Drug resistance in tuberculosis; Filtration; Flow Cytometry; Genetic Heterogeneity; Genome; Genotype; Genus Mycobacterium; Growth; Household; Individual; Intervention; Label; Laboratories; Laboratory culture; Link; Liquid substance; Metabolic; Methods; Minority; Modeling; Molecular; Mycobacterium tuberculosis; Organism; Patients; Population; Prevalence; Public Health; Recovery; Rifampin; Sampling; Site; Source; South Africa; Specimen; Sputum; Surveys; Symptoms; Techniques; Testing; Tuberculosis; base; community setting; drug-sensitive; genome sequencing; indexing; insight; member; novel; novel strategies; patient subsets; quantum; success; transmission process; whole genome

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.

1 项目概要 2 迄今为止，大多数结核病 (TB) 结核病传播研究在很大程度上依赖于标准细菌培养 3.从痰中判断传播途径。这种方法的基本假设是标准 4 种培养方法可以恢复所有传播的菌株。此外，未报告结核病的个人 出现5种症状且痰培养阴性者被推定为非传染性。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 痰中存在 7 种差异可培养的结核杆菌 (DCTB)，它们无法在标准培养物中生长，只能 8 出现在补充有培养物滤液 (CF) 的液体培养基中，挑战了普遍的假设并具有 9 对结核病传播的重要影响。痰中 DCTB 的存在表明标准培养 10 未能检测到与结核病传播相关的大部分细菌种群。 11 我们假设对痰液进行 DCTB 检测将提高细菌数量 12 恢复并与标准培养物相比将鉴定出更多的细菌基因型。这将有利于 13 建立标准文化可能遗漏的传输链路。对于指数结核病患者，我们将 14 首先通过对标准痰中出现的细菌基因型进行深入表征来探索这一点 15 培养物与 DCTB 测定中出现的培养物进行比较。细菌菌株的基因型为 通过全基因组测序鉴定出 16 个。我们将重点关注药物敏感和利福平单一耐药结核病， 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。下列的 18 指标患者的特征，我们将使用 DCTB 检测来增加细菌产量和基因型多样性 19人从家庭接触者的痰液中康复。然后我们将使用传输推理模型来 20 在家庭中建立了新的传播链接，这些链接被 DCTB 检测检测到，但未使用 21标准文化。此外，我们将测试新型荧光探针的实用性，这些探针将活的分枝杆菌标记为 22 另一种研究家庭接触者痰液中极低细菌含量的方法，该方法可能不适用 通过 DCTB 检测检测到 23 种。 24 我们预计这种方法将为家庭结核病传播提供新的见解，从而 25 允许针对这种情况进行有效的传播阻断干预措施。此外，应用程序 26 项 DCTB 检测与新兴分离株的深入全基因组测序相结合将验证新的 研究结核病传播的 27 种方法。