Centre International de Recherche en Infectiologie, Team Horizontal Gene Transfer in Bacterial Pathogens, INSERM U1111, Université Claude Bernard Lyon 1, CNRS UMR 5308, École Normale Supérieure de Lyon, Université de Lyon, Villeurbanne, France.
Université de Lyon, VetAgro Sup, Marcy l'Etoile, France.
Appl Environ Microbiol. 2021 Aug 26;87(18):e0074721. doi: 10.1128/AEM.00747-21.
Here, we sought to test the resistance of human pathogens to unaltered environmental free-living amoebae. Amoebae are ubiquitous eukaryotic microorganisms and important predators of bacteria. Environmental amoebae have also been proposed to serve as both potential reservoirs and training grounds for human pathogens. However, studies addressing their relationships with human pathogens often rely on a few domesticated amoebae that have been selected to feed on rich medium, thereby possibly overestimating the resistance of pathogens to these predatory phagocytes. From an open-air composting site, we recovered over 100 diverse amoebae that were able to feed on Acinetobacter baumannii and Klebsiella pneumoniae. In a standardized and quantitative assay for predation, the isolated amoebae showed a broad predation spectrum, killing clinical isolates of A. baumannii, K. pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Interestingly, A. baumannii, which was previously reported to resist predation by laboratory strains of , was efficiently consumed by closely related environmental amoebae. The isolated amoebae were capable of feeding on highly virulent carbapenem-resistant or methicillin-resistant clinical isolates. In conclusion, the natural environment is a rich source of amoebae with broad-spectrum bactericidal activities, including against antibiotic-resistant isolates. Free-living amoebae have been proposed to play an important role in hosting and disseminating various human pathogens. The resistance of human pathogens to predation by amoebae is often derived from experiments using model amoebae. Here, we sought to isolate environmental amoebae and to test their predation on diverse human pathogens, with results that challenge conclusions based on model amoebae. We found that the natural environment is a rich source of diverse amoebae with broad-spectrum predatory activities against human pathogens, including highly virulent and antibiotic-resistant clinical isolates.
在这里，我们试图测试人类病原体对未改变的环境自由生活变形虫的抵抗力。变形虫是普遍存在的真核微生物，是细菌的重要捕食者。环境变形虫也被认为是人类病原体的潜在储主和训练场。然而，研究它们与人类病原体的关系的研究通常依赖于少数经过驯化的变形虫，这些变形虫被选择在丰富的培养基上进食，从而可能高估了病原体对这些吞噬性吞噬细胞的抵抗力。从一个露天堆肥场，我们回收了 100 多种不同的变形虫，这些变形虫能够以鲍曼不动杆菌和肺炎克雷伯菌为食。在一种标准化和定量的捕食测定中，分离出的变形虫表现出广泛的捕食谱，能够杀死鲍曼不动杆菌、肺炎克雷伯菌、铜绿假单胞菌和金黄色葡萄球菌的临床分离株。有趣的是，以前有报道称实验室菌株的鲍曼不动杆菌抵抗吞噬作用，但现在被发现可以被密切相关的环境变形虫有效地消耗。分离出的变形虫能够以高毒力的碳青霉烯类耐药或耐甲氧西林的临床分离株为食。总之，自然环境是具有广谱杀菌活性的变形虫的丰富来源，包括对抗生素耐药分离株。自由生活的变形虫被认为在宿主和传播各种人类病原体方面发挥着重要作用。人类病原体对变形虫捕食的抵抗力通常来自于使用模型变形虫的实验。在这里，我们试图分离环境变形虫并测试它们对多种人类病原体的捕食作用，结果挑战了基于模型变形虫的结论。我们发现，自然环境是具有广谱捕食活性的多种变形虫的丰富来源，能够捕食人类病原体，包括高毒力和抗生素耐药的临床分离株。
