Aix-Marseille Université, IRD, APHM, MEPHI, IHU Méditerranée Infection, Marseille, France.
Aix Marseille Université, IRD, AP-HM, SSA, VITROME, IHU Méditerranée Infection Marseille, France.
Front Cell Infect Microbiol. 2023 Jul 27;13:1195679. doi: 10.3389/fcimb.2023.1195679. eCollection 2023.
Candidate Phyla Radiation (CPR) and more specifically Candidatus Saccharibacteria (TM7) have now been established as ubiquitous members of the human oral microbiota. Additionally, CPR have been reported in the gastrointestinal and urogenital tracts. However, the exploration of new human niches has been limited to date.
In this study, we performed a prospective and retrospective screening of TM7 in human samples using standard PCR, real-time PCR, scanning electron microscopy (SEM) and shotgun metagenomics.
Using Real-time PCR and standard PCR, oral samples presented the highest TM7 prevalence followed by fecal samples, breast milk samples, vaginal samples and urine samples. Surprisingly, TM7 were also detected in infectious samples, namely cardiac valves and blood cultures at a low prevalence (under 3%). Moreover, we observed CPR-like structures using SEM in all sample types except cardiac valves. The reconstruction of TM7 genomes in oral and fecal samples from shotgun metagenomics reads further confirmed their high prevalence in some samples.
This study confirmed, through their detection in multiple human samples, that TM7 are human commensals that can also be found in clinical settings. Their detection in clinical samples warrants further studies to explore their role in a pathological setting.
候选门纲目科属种辐射（CPR），特别是候选糖细菌（TM7），现已被确定为人类口腔微生物群的普遍成员。此外，CPR 也已在胃肠道和泌尿生殖道中报道过。然而，迄今为止，对新的人类小生境的探索还很有限。
在这项研究中，我们使用标准 PCR、实时 PCR、扫描电子显微镜 (SEM) 和鸟枪法宏基因组学对人类样本中的 TM7 进行了前瞻性和回顾性筛选。
使用实时 PCR 和标准 PCR，口腔样本的 TM7 检出率最高，其次是粪便样本、母乳样本、阴道样本和尿液样本。令人惊讶的是，TM7 也在感染性样本中检测到，即在心脏瓣膜和血液培养物中的检出率较低（低于 3%）。此外，我们在除心脏瓣膜外的所有样本类型中均使用 SEM 观察到 CPR 样结构。从鸟枪法宏基因组读数中重建 TM7 基因组进一步证实了它们在一些样本中的高检出率。
本研究通过在多种人类样本中检测到 TM7，证实了它们是人类共生菌，也可以在临床环境中发现。它们在临床样本中的检出值得进一步研究，以探索它们在病理环境中的作用。
