Berg Gabriele, Eberl Leo, Hartmann Anton
University of Rostock, Department of Life Sciences, Institute of Microbiology, Albert-Einstein-Strasse 3, D-18051 Rostock, Germany.
Environ Microbiol. 2005 Nov;7(11):1673-85. doi: 10.1111/j.1462-2920.2005.00891.x.
During the last years, the number of human infections caused by opportunistic pathogens has increased dramatically. One natural reservoir of opportunistic pathogens is the rhizosphere, the zone around roots that is influenced by the plant. Due to a high content of nutrients, this habitat is a 'microbial hot-spot', where bacterial abundances including those with strong antagonistic traits are enhanced. Various bacterial genera, including Burkholderia, Enterobacter, Herbaspirillum, Ochrobactrum, Pseudomonas, Ralstonia, Staphylococcus and Stenotrophomonas, contain root-associated strains that can encounter bivalent interactions with both plant and human hosts. Mechanisms responsible for colonization of the rhizosphere and antagonistic activity against plant pathogens are similar to those responsible for colonization of human organs and tissues, and pathogenicity. Multiple resistances against antibiotics are not only found with clinical strains but also with strains isolated from the rhizosphere. High competition, the occurrence of diverse antibiotics in the rhizosphere, and enhanced horizontal gene transfer rates in this microenvironment appear to contribute to the high levels of natural resistances. While opportunistic bacteria from the rhizosphere have some properties in common, each of these emerging pathogens has its own features, which are discussed in detail for Burkholderia, Ochrobactrum and Stenotrophomonas.
在过去几年中，由机会致病菌引起的人类感染数量急剧增加。机会致病菌的一个天然储存库是根际，即受植物影响的根周围区域。由于营养成分含量高，这个栖息地是一个“微生物热点”，包括具有强拮抗特性的细菌在内的细菌丰度在此处会增加。包括伯克霍尔德菌属、肠杆菌属、草螺菌属、苍白杆菌属、假单胞菌属、劳尔氏菌属、葡萄球菌属和嗜麦芽窄食单胞菌属在内的各种细菌属，都含有与根相关的菌株，这些菌株可能会与植物和人类宿主发生双向相互作用。负责根际定殖和对植物病原体拮抗活性的机制与负责人类器官和组织定殖以及致病性的机制相似。不仅临床菌株，而且从根际分离出的菌株都存在多重抗生素耐药性。高度竞争、根际中多种抗生素的存在以及该微环境中水平基因转移率的提高似乎导致了高水平的天然耐药性。虽然来自根际的机会性细菌有一些共同特性，但这些新兴病原体中的每一种都有其自身的特点，本文将针对伯克霍尔德菌属、苍白杆菌属和嗜麦芽窄食单胞菌属进行详细讨论。
