Genome sequencing and comparative genomics of enterohemorrhagic Escherichia coli O145:H25 and O145:H28 reveal distinct evolutionary paths and marked variations in traits associated with virulence & colonization

BMC Microbiology

Research Article

Narjol Gonzalez-Escalona¹  Julie A. Kase¹  Sandra C. Lorenz²  Michael L. Kotewicz³  Markus Fischer⁴ 

[1] U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Division of Microbiology, 20740, College Park, MD, USA;U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Division of Microbiology, 20740, College Park, MD, USA;University of Hamburg, Hamburg School of Food Science, Institute of Food Chemistry, 20146, Hamburg, Germany;U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Division of Molecular Biology, 20708, Laurel, MD, USA;University of Hamburg, Hamburg School of Food Science, Institute of Food Chemistry, 20146, Hamburg, Germany;

关键词: EHEC O145:H25;    Next generation sequencing;    Comparative genomics;    Phylogenetics;    Bacterial adaptation & colonization;   

DOI  :  10.1186/s12866-017-1094-3

 received in 2017-04-25, accepted in 2017-08-14,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundEnterohemorrhagic Escherichia coli (EHEC) O145 are among the top non-O157 serogroups associated with severe human disease worldwide. Two serotypes, O145:H25 and O145:H28 have been isolated from human patients but little information is available regarding the virulence repertoire, origin and evolutionary relatedness of O145:H25. Hence, we sequenced the complete genome of two O145:H25 strains associated with hemolytic uremic syndrome (HUS) and compared the genomes with those of previously sequenced O145:H28 and other EHEC strains.ResultsThe genomes of the two O145:H25 strains were 5.3 Mbp in size; slightly smaller than those of O145:H28 and other EHEC strains. Both strains contained three nearly identical plasmids and several prophages and integrative elements, many of which differed significantly in size, gene content and organization as compared to those present in O145:H28 and other EHECs. Furthermore, notable variations were observed in several fimbrial gene cluster and intimin types possessed by O145:H25 and O145:H28 indicating potential adaptation to distinct areas of host colonization. Comparative genomics further revealed that O145:H25 are genetically more similar to other non-O157 EHEC strains than to O145:H28.ConclusionPhylogenetic analysis accompanied by comparative genomics revealed that O145:H25 and O145:H28 evolved from two separate clonal lineages and that horizontal gene transfer and gene loss played a major role in the divergence of these EHEC serotypes. The data provide further evidence that ruminants might be a possible reservoir for O145:H25 but that they might be impaired in their ability to establish a persistent colonization as compared to other EHEC strains.

【 授权许可】

CC BY   
© The Author(s). 2017