title: Molecular Characterization of Human Atypical Sorbitol-Fermenting Enteropathogenic Escherichia coli O157 Reveals High Diversity.
abstract: Alongside the well-characterized enterohemorrhagic Escherichia coli (EHEC) O157:H7, serogroup O157 comprises sorbitol-fermenting typical and atypical enteropathogenic E. coli (EPEC/aEPEC) strains that carry the intimin-encoding gene eae but not Shiga toxin-encoding genes (stx). Since little is known about these pathogens, we characterized 30 clinical isolates from patients with hemolytic uremic syndrome (HUS) or uncomplicated diarrhea with respect to their flagellin gene (fliC) type and multilocus sequence type (MLST). Moreover, we applied whole-genome sequencing (WGS) to determine the phylogenetic relationship with other eae-positive EHEC serotypes and the composition of the rfbO157 region. fliC typing resulted in five fliC types (H7, H16, H34, H39, and H45). Isolates of each fliC type shared a unique ST. In comparison to the 42 HUS-associated E. coli (HUSEC) strains, only the stx-negative isolates with fliCH7 shared their ST with EHEC O157:H7/H(-) strains. With the exception of one O157:H(-) fliCH16 isolate, HUS was exclusively associated with fliCH7. WGS corroborated the separation of the fliCH7 isolates, which were closely related to the EHEC O157:H7/H(-) isolates, and the diverse group of isolates exhibiting different fliC types, indicating independent evolution of the different serotypes. This was also supported by the heterogeneity within the rfbO157 region that exhibited extensive recombinations. The genotypic subtypes and distribution of clinical symptoms suggested that the stx-negative O157 strains with fliCH7 were originally EHEC strains that lost stx The remaining isolates form a distinct and diverse group of atypical EPEC isolates that do not possess the full spectrum of virulence genes, underlining the importance of identifying the H antigen for clinical risk assessment.
authors.affiliation: Institute of Hygiene and National Consulting Laboratory for Hemolytic Uremic Syndrome (HUS), University Hospital Muenster, Münster, Germany.
authors.forename: Annelene
authors.initials: A
authors.lastname: Kossow
authors.affiliation: Institute of Hygiene and National Consulting Laboratory for Hemolytic Uremic Syndrome (HUS), University Hospital Muenster, Münster, Germany.
authors.forename: Wenlan
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Institute of Hygiene and National Consulting Laboratory for Hemolytic Uremic Syndrome (HUS), University Hospital Muenster, Münster, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Bielaszewska
authors.affiliation: Institute of Hygiene and National Consulting Laboratory for Hemolytic Uremic Syndrome (HUS), University Hospital Muenster, Münster, Germany.
authors.forename: Sophie
authors.initials: S
authors.lastname: Rhode
authors.affiliation: Institute of Hygiene and National Consulting Laboratory for Hemolytic Uremic Syndrome (HUS), University Hospital Muenster, Münster, Germany.
authors.forename: Kevin
authors.initials: K
authors.lastname: Hansen
authors.affiliation: National Reference Centre for Salmonella and Other Bacterial Enterics, Robert Koch-Institute, Wernigerode, Germany.
authors.forename: Angelika
authors.initials: A
authors.lastname: Fruth
authors.affiliation: Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Rüter
authors.affiliation: Institute of Hygiene and National Consulting Laboratory for Hemolytic Uremic Syndrome (HUS), University Hospital Muenster, Münster, Germany.
authors.forename: Helge
authors.initials: H
authors.lastname: Karch
authors.affiliation: Institute of Hygiene and National Consulting Laboratory for Hemolytic Uremic Syndrome (HUS), University Hospital Muenster, Münster, Germany mellmann@uni-muenster.de.
authors.forename: Alexander
authors.identifier: 0000-0002-0649-5185
authors.initials: A
authors.lastname: Mellmann
mesh_terms: D003967:Diarrhea / Q000382:microbiology; D054308:Enteropathogenic Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000382:microbiology; D019453:Escherichia coli O157 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics; D005285:Fermentation; D014644:Genetic Variation; D016680:Genome, Bacterial; D006463:Hemolytic-Uremic Syndrome / Q000382:microbiology; D006801:Humans; D058889:Molecular Typing; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013012:Sorbitol / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D013012:Sorbitol