Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Konggrid.35030.35, Kowloon, Hong Kong.
National Engineering Laboratory for Deep Process of Rice and By-Products, Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, Hunan Key Laboratory of Processed Food for Special Medical Purpose, College of Food Science and Engineering, Central South University of Forestry and Technology, Changsha, Hunan, China.
Microbiol Spectr. 2022 Jun 29;10(3):e0252821. doi: 10.1128/spectrum.02528-21. Epub 2022 May 23.
A plasmid that harbored the virulence factors highly like those of the virulence plasmid commonly found in clinical hypervirulent Klebsiella pneumoniae strains was detected in a foodborne Escherichia coli strain EC1108 and designated p1108-IncFIB. This virulent-like plasmid was found to be common in E. coli from various sources. To understand the contribution of this plasmid to the virulence of E. coli, plasmid p1108-IncFIB in strain EC1108 was first cured to generate strain EC1108-PC. The virulence plasmid p15WZ-82_Vir in Klebsiella pneumoniae strain 15WZ-82 was then transmitted to EC1108-PC to produce the transconjugant, EC1108-PC-TC to assess the contribution of this virulence plasmid to the virulence level of E. coli. During the process of conjugation, p15WZ-82_Vir was found to be evolved into p15WZ-82_int, which underwent homologous recombination with a plasmid encoding a carbapenemase gene, , p1108-NDM, in EC1108-PC. Comparison between the level of virulence in the EC1108, EC1108-PC-TC, and EC1108-PC through serum and macrophage resistance assay, as well as animal experiments, confirmed that plasmid p1108-IncFIB encoded a high level of virulence in E. coli, yet the fusion plasmid derived from p15WZ-82_Vir did not encode virulence but instead imposed a high fitness cost in the E. coli strain EC1108-PC-TC. These findings indicate that E. coli strains carrying the virulence plasmid p1108-IncFIB in multidrug-resistant (MDR) strains may also impose serious public health threats like that of hypervirulent Klebsiella pneumoniae strains harboring the p15WZ-82_Vir plasmid. Acquisition of pLVPK-like virulence plasmid by Klebsiella pneumoniae converts it to hypervirulent K. pneumoniae (HvKP), which has become one of the most important clinical bacterial pathogens. The potential of transmission of this virulence plasmid and its contribution to the virulence of other Enterobacteriaceae, such as E. coli, are not clear yet. In this study, we showed that pLVPK-like virulence plasmid exhibited fitness costs and did not contribute to the virulence in E. coli. However, we identified a novel virulence plasmid, p1108-IncFIB, that encodes similar siderophore genes as those of pLVPK from a foodborne E. coli strain and showed that p1108-IncFIB encoded a high level of virulence in E. coli. BLAST of E. coli genomes from GenBank showed that these siderophore genes were widespread in clinical E. coli strains. Further studies are warranted to understand the impact of this plasmid in the control of clinical infections caused by E. coli.
一个质粒，其携带的毒力因子高度类似于临床高毒力肺炎克雷伯菌菌株中常见的毒力质粒，在食源性病原体大肠杆菌菌株 EC1108 中被检测到，并被命名为 p1108-IncFIB。这种类似毒力的质粒在来自不同来源的大肠杆菌中很常见。为了了解该质粒对大肠杆菌毒力的贡献，首先将质粒 p1108-IncFIB 从菌株 EC1108 中去除，生成菌株 EC1108-PC。然后将肺炎克雷伯菌 15WZ-82 菌株中的毒力质粒 p15WZ-82_Vir 传递到 EC1108-PC 中，产生转导子 EC1108-PC-TC，以评估该毒力质粒对大肠杆菌毒力水平的贡献。在接合过程中，发现 p15WZ-82_Vir 进化为 p15WZ-82_int，与 EC1108-PC 中编码碳青霉烯酶基因的质粒 p1108-NDM 发生同源重组。通过血清和巨噬细胞抗性测定以及动物实验比较 EC1108、EC1108-PC-TC 和 EC1108-PC 的毒力水平，证实质粒 p1108-IncFIB 在大肠杆菌中编码高水平的毒力，而源自 p15WZ-82_Vir 的融合质粒则不编码毒力，但在大肠杆菌菌株 EC1108-PC-TC 中施加了高适应性成本。这些发现表明，携带多药耐药（MDR）菌株中毒力质粒 p1108-IncFIB 的大肠杆菌菌株也可能像携带 p15WZ-82_Vir 质粒的高毒力肺炎克雷伯菌菌株一样，对公共健康构成严重威胁。
肺炎克雷伯菌获得 LVPK 样毒力质粒可使其转化为高毒力肺炎克雷伯菌（HvKP），这已成为最重要的临床细菌病原体之一。这种毒力质粒的传播潜力及其对其他肠杆菌科细菌（如大肠杆菌）毒力的贡献尚不清楚。在本研究中，我们表明 LVPK 样毒力质粒表现出适应性成本，并且不有助于大肠杆菌的毒力。然而，我们从食源性病原体大肠杆菌菌株中鉴定出一种新型毒力质粒 p1108-IncFIB，该质粒编码与 LVPK 相似的铁载体基因，并表明 p1108-IncFIB 在大肠杆菌中编码高水平的毒力。对 GenBank 中大肠杆菌基因组的 BLAST 分析表明，这些铁载体基因在临床大肠杆菌菌株中广泛存在。需要进一步研究以了解该质粒在控制由大肠杆菌引起的临床感染中的影响。
