Institute for Global Health, University College London, London, UK.
Centre for Clinical Microbiology, University College London, London, UK.
Sci Rep. 2024 Oct 30;14(1):26108. doi: 10.1038/s41598-024-74318-3.
When processed in solid or liquid medium, tuberculosis patient samples yield different proportions of a heterogenous bacterial community over the duration of treatment. We aimed to derive a relationship between methodologies for bacterial load determination and assess the effect of the growth phase of the parent culture and its exposure to stress on the results. Mycobacterium tuberculosis H37Rv was grown with and without antibiotic (isoniazid or rifampicin) and sampled on day 0, 3, 11 and 21 of growth in broth culture. The bacterial load was estimated by colony counts and the BD BACTEC MGIT system. Linear and nonlinear mixed-effects models were used to describe the relationship between time-to-positivity (TTP) and time-to-growth (TTG) versus colony forming units (CFU), and growth units (GU) versus incubation time in MGIT. For samples with the same CFU, antibiotic-treated and stationary phase cells had a shorter TTP than antibiotic-free controls and early-logarithmic phase cells, respectively. Similarly, stationary phase samples reached higher GUs and had shorter TTG than early-log phase ones. This suggests that there is a population of bacterial cells that can be differentially recovered in liquid medium, giving us insight into the physiological states of the original culture, aiding the interpretation of clinical trial outputs.
在固体或液体培养基中处理时，肺结核患者样本在治疗过程中会产生不同比例的异质细菌群落。我们旨在建立细菌载量测定方法之间的关系，并评估亲代培养物的生长阶段及其暴露于应激对结果的影响。结核分枝杆菌 H37Rv 在有或没有抗生素（异烟肼或利福平）的情况下生长，并在肉汤培养的第 0、3、11 和 21 天采样。细菌载量通过菌落计数和 BD BACTEC MGIT 系统进行估计。线性和非线性混合效应模型用于描述 TTP 和 TTG 与 CFU 以及 MGIT 中的培养时间与生长单位（GU）之间的关系。对于具有相同 CFU 的样本，与无抗生素对照和早期对数期细胞相比，经抗生素处理的静止期细胞具有更短的 TTP。同样，与早期对数期相比，静止期样品达到更高的 GU 并具有更短的 TTG。这表明在液体培养基中可以不同程度地回收细菌细胞，这使我们深入了解原始培养物的生理状态，有助于解释临床试验结果。
