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首页> 外文期刊>Infection and immunity >Molecular Analysis of Asymptomatic Bacteriuria Escherichia coli Strain VR50 Reveals Adaptation to the Urinary Tract by Gene Acquisition
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Molecular Analysis of Asymptomatic Bacteriuria Escherichia coli Strain VR50 Reveals Adaptation to the Urinary Tract by Gene Acquisition

机译：无症状细菌性大肠杆菌VR50菌株的分子分析揭示了通过基因采集对尿道的适应

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Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli responsible for >80% of all cases. One extreme of UTI is asymptomatic bacteriuria (ABU), which occurs as an asymptomatic carrier state that resembles commensalism. To understand the evolution and molecular mechanisms that underpin ABU, the genome of the ABU E. coli strain VR50 was sequenced. Analysis of the complete genome indicated that it most resembles E. coli K-12, with the addition of a 94-kb genomic island (GI-VR50-pheV), eight prophages, and multiple plasmids. GI-VR50-pheV has a mosaic structure and contains genes encoding a number of UTI-associated virulence factors, namely, Afa (afimbrial adhesin), two autotransporter proteins (Ag43 and Sat), and aerobactin. We demonstrated that the presence of this island in VR50 confers its ability to colonize the murine bladder, as a VR50 mutant with GI-VR50-pheV deleted was attenuated in a mouse model of UTI in vivo. We established that Afa is the island-encoded factor responsible for this phenotype using two independent deletion (Afa operon and AfaE adhesin) mutants. E. coli VR50afa and VR50afaE displayed significantly decreased ability to adhere to human bladder epithelial cells. In the mouse model of UTI, VR50afa and VR50afaE displayed reduced bladder colonization compared to wild-type VR50, similar to the colonization level of the GI-VR50-pheV mutant. Our study suggests that E. coli VR50 is a commensal-like strain that has acquired fitness factors that facilitate colonization of the human bladder.
机译：尿路感染（UTI）是人类最常见的传染病，其中大肠杆菌占所有病例的80％以上。 UTI的一种极端情况是无症状菌尿症（ABU），它是一种无症状的携带态，类似于共鸣症。为了了解支持ABU的进化和分子机制，对ABU大肠杆菌VR50菌株的基因组进行了测序。对完整基因组的分析表明，它与大肠杆菌K-12最相似，除了有一个94-kb的基因组岛（GI-VR50-pheV），八个噬菌体和多个质粒。 GI-VR50-pheV具有镶嵌结构，并包含编码许多与UTI相关的毒力因子的基因，即Afa（肢端粘附素），两种自转运蛋白（Ag43和Sat）和航空杆菌素。我们证明了该岛在VR50中的存在赋予其殖民鼠膀胱的能力，因为缺失GI-VR50-pheV的VR50突变体在体内UTI小鼠模型中减弱了。我们使用两个独立的缺失突变体（Afa操纵子和AfaE黏附素）确定Afa是对此表型负责的岛编码因子。大肠杆菌VR50afa和VR50afaE表现出显着降低的粘附于人膀胱上皮细胞的能力。在UTI小鼠模型中，与野生型VR50相比，VR50afa和VR50afaE的膀胱定植减少，类似于GI-VR50-pheV突变体的定植水平。我们的研究表明，大肠杆菌VR50是一种类似共生的菌株，已获得了促进人膀胱定植的适应因子。

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