Do Carmo Silva Phoebe, Hill Darryl, Harrison Freya
School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1QU, UK.
Access Microbiol. 2025 Jun 20;7(6). doi: 10.1099/acmi.0.000979.v3. eCollection 2025.
Non-typeable (NTHi) is an early pathogen isolated from the lungs of children with cystic fibrosis (CF). However, its role in the progression of CF lung infection is poorly understood. Additionally, whether it forms biofilms in the lungs of people with CF is an open question. The development of synthetic CF sputum media (SCFM) has given key insights into the microbiology of later CF pathogens, and , through replicating the chemical composition of CF sputum. However, the growth of NTHi in these media has not previously been reported. We show that NTHi grows poorly in three variants of SCFM commonly used to induce -like growth of and (SCFM1, SCFM2 and SCFM3). The addition of NAD and haemin to SCFM1 and SCFM2 promoted the planktonic growth and biofilm formation of both laboratory and clinical NTHi isolates, and we were able to develop a modified variant of SCFM2 that allows culture of NTHis. We show that NTHi cannot be identified in an established model of CF infection, which uses SCFM and porcine bronchiolar tissue. This may in part be due to the presence of endogenous bacteria on the pig lung tissue, which outcompete NTHi, but the lack of selective agar to isolate NTHi from endogenous bacteria, and the fact that NTHi is an exclusively human pathogen, makes it hard to conclude that this is the case. Through spiking modified SCFM2 with filter-sterilized lung homogenate, biofilm growth of clinical NTHi isolates was enhanced. Our results highlight that there are crucial components present in the lung tissue, which NTHi require for growth, which are not present in any published variant of SCFM from the Palmer Endres and Konstan in JAMA (2022;137:191-1) lineage. Our results may inform future modifications to SCFM recipes to truly mimic the environment of CF lung sputum and thus, to facilitate the study of a wide range of CF pathogens.
不可分型流感嗜血杆菌（NTHi）是从囊性纤维化（CF）患儿肺部分离出的早期病原体。然而，其在CF肺部感染进展中的作用尚不清楚。此外，它是否在CF患者肺部形成生物膜仍是一个悬而未决的问题。合成CF痰液培养基（SCFM）的开发通过复制CF痰液的化学成分，为后期CF病原体的微生物学提供了关键见解。然而，此前尚未报道NTHi在这些培养基中的生长情况。我们发现，NTHi在常用于诱导铜绿假单胞菌和金黄色葡萄球菌样生长的三种SCFM变体（SCFM1、SCFM2和SCFM3）中生长不佳。向SCFM1和SCFM2中添加烟酰胺腺嘌呤二核苷酸（NAD）和血红素可促进实验室和临床NTHi分离株的浮游生长和生物膜形成，并且我们能够开发出一种改良的SCFM2变体，用于培养NTHi。我们发现，在使用SCFM和猪细支气管组织建立的CF感染模型中无法鉴定出NTHi。这可能部分是由于猪肺组织上存在内源性细菌，它们会与NTHi竞争，但缺乏从内源性细菌中分离NTHi的选择性琼脂，而且NTHi是一种仅感染人类的病原体，因此很难确定情况是否如此。通过向改良的SCFM2中加入经滤菌的肺匀浆，临床NTHi分离株的生物膜生长得到增强。我们的结果表明，肺组织中存在NTHi生长所需的关键成分，而帕尔默、恩德斯和康斯坦在《美国医学会杂志》（2022年；137:191 - 1）系列中发表的任何SCFM变体中都不存在这些成分。我们的结果可能为未来SCFM配方的改进提供参考，以真正模拟CF肺痰液的环境，从而促进对多种CF病原体的研究。
