Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
Genome Biol Evol. 2013;5(8):1524-35. doi: 10.1093/gbe/evt111.
Reasons for the rising clinical impact of the bacterium Enterococcus faecium include the species' rapid acquisition of adaptive genetic elements. Here, we focused on the impact of recombination on the evolution of E. faecium. We used the recently developed BratNextGen algorithm to detect recombinant regions in the core genome of 34 E. faecium strains, including three newly sequenced clinical strains. Recombination was found to have a significant impact on the E. faecium genome: of the original 1.2 million positions in the core genome, 0.5 million were predicted to have been affected by recombination in at least one strain. Importantly, strains in one of the two major E. faecium clades (clade B), which contains most of the E. faecium human gut commensals, formed the most important reservoir for donating foreign DNA to the second major E. faecium clade (clade A), which contains most of the clinical isolates. Also, several genomic regions were found to mainly recombine in specific hospital-associated E. faecium strains. One of these regions (the epa-like locus) likely encodes the biosynthesis of cell wall polysaccharides. These findings suggest a crucial role for recombination in the emergence of E. faecium as a successful hospital-associated pathogen.
粪肠球菌临床影响上升的原因包括该物种快速获得适应性遗传元件。在这里，我们关注重组对粪肠球菌进化的影响。我们使用最近开发的 BratNextGen 算法检测了 34 株粪肠球菌核心基因组中的重组区域，包括 3 株新测序的临床菌株。重组对粪肠球菌基因组有重大影响：在核心基因组的 120 万个原始位置中，至少有一种菌株预测有 50 万个位置受到重组的影响。重要的是，两个主要粪肠球菌进化枝（进化枝 B）之一的菌株形成了向第二个主要进化枝（进化枝 A）提供外源 DNA 的最重要来源，进化枝 A 包含了大多数临床分离株。此外，还发现了几个基因组区域主要在特定的医院相关粪肠球菌菌株中重组。其中一个区域（epa 样基因座）可能编码细胞壁多糖的生物合成。这些发现表明，重组在粪肠球菌作为一种成功的医院相关病原体出现中起着关键作用。
