Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal.
Front Cell Infect Microbiol. 2018 Apr 4;8:97. doi: 10.3389/fcimb.2018.00097. eCollection 2018.
is a ubiquitous bacterium in freshwater environments and in many man-made water systems capable of inducing pneumonia in humans. Despite its ubiquitous character most studies on virulence focused on clinical strains and isolates from man-made environments, so little is known about the nature and extent of virulence variation in strains isolated from natural environments. It has been established that clinical isolates are less diverse than man-made and natural environmental strains, suggesting that only a subset of environmental isolates is specially adapted to infect humans. In this work we intended to determine if unrelated strains, isolated from different environments and with distinct virulence-related genetic backgrounds, displayed differences in virulence, using the Wax Moth infection model. We found that all tested strains were pathogenic in , regardless of their origin. Indeed, a panoply of virulence-related phenotypes was observed sustaining the existence of significant differences on the ability of strains to induce disease. Taken together our results suggest that the occurrence of human infection is not related with the increased capability of some strains to induce disease since we also found a concentration threshold above which strains are equally able to cause disease. In addition, no link could be established between the sequence-type (ST) and pathogenicity. We envision that in man-made water distribution systems environmental filtering selection and biotic competition acts structuring populations by selecting more resilient and adapted strains that can rise to high concentration if no control measures are implemented. Therefore, public health strategies based on the sequence based typing (STB) scheme analysis should take into account that the major disease-associated clones of were not related with higher virulence in infection model, and that potential variability of virulence-related phenotypes was found within the same ST.
是一种普遍存在于淡水环境和许多人工水系统中的细菌，能够引起人类肺炎。尽管其普遍存在，但大多数关于毒力的研究都集中在临床菌株和人工环境分离株上，因此对天然环境分离株的毒力变异的性质和程度知之甚少。已经确定临床分离株的多样性低于人工和自然环境分离株，这表明只有一部分环境分离株特别适应感染人类。在这项工作中，我们旨在使用黄毒蛾感染模型确定来自不同环境且具有不同与毒力相关的遗传背景的无关 菌株是否在毒力方面存在差异。我们发现，所有测试的菌株在 中都是致病的，无论其来源如何。事实上，观察到了一系列与毒力相关的表型，这支持了 菌株诱导疾病的能力存在显著差异的存在。总之，我们的结果表明，人类感染的发生与某些菌株诱导疾病能力的提高无关，因为我们还发现了一个浓度阈值，超过该阈值， 菌株就能够同样引起疾病。此外，序列型 (ST) 和 致病性之间没有联系。我们设想，在人工水分配系统中，环境过滤选择和生物竞争通过选择更有弹性和适应性的菌株来结构种群，如果不实施控制措施，这些菌株可以在高浓度下出现。因此，基于基于序列的分型 (STB) 方案分析的公共卫生策略应该考虑到与主要疾病相关的 克隆与感染模型中更高的毒力无关，并且在相同的 ST 中发现了与毒力相关的表型的潜在可变性。
