title: Is Shiga Toxin-Negative Escherichia coli O157:H7 Enteropathogenic or Enterohemorrhagic Escherichia coli? Comprehensive Molecular Analysis Using Whole-Genome Sequencing.
abstract: The ability of Escherichia coli O157:H7 to induce cellular damage leading to disease in humans is related to numerous virulence factors, most notably the stx gene, encoding Shiga toxin (Stx) and carried by a bacteriophage. Loss of the Stx-encoding bacteriophage may occur during infection or culturing of the strain. Here, we collected stx-positive and stx-negative variants of E. coli O157:H7/NM (nonmotile) isolates from patients with gastrointestinal complaints. Isolates were characterized by whole-genome sequencing (WGS), and their virulence properties and phylogenetic relationship were determined. Because of the presence of the eae gene but lack of the bfpA gene, the stx-negative isolates were considered atypical enteropathogenic E. coli (aEPEC). However, they had phenotypic characteristics similar to those of the Shiga toxin-producing E. coli (STEC) isolates and belonged to the same sequence type, ST11. Furthermore, EPEC and STEC isolates shared similar virulence genes, the locus of enterocyte effacement region, and plasmids. Core genome phylogenetic analysis using a gene-by-gene typing approach showed that the sorbitol-fermenting (SF) stx-negative isolates clustered together with an SF STEC isolate and that one non-sorbitol-fermenting (NSF) stx-negative isolate clustered together with NSF STEC isolates. Therefore, these stx-negative isolates were thought either to have lost the Stx phage or to be a progenitor of STEC O157:H7/NM. As detection of STEC infections is often based solely on the identification of the presence of stx genes, these may be misdiagnosed in routine laboratories. Therefore, an improved diagnostic approach is required to manage identification, strategies for treatment, and prevention of transmission of these potentially pathogenic strains.
authors: Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: Mithila
authors: M
authors: Ferdous
authors: Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: Kai
authors: K
authors: Zhou
authors: Institute of Hygiene, University Hospital Münster, Münster, Germany.
authors: Alexander
authors: http://orcid.org/0000-0002-0649-5185
authors: A
authors: Mellmann
authors: Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy.
authors: Stefano
authors: S
authors: Morabito
authors: Star-MDC, Rotterdam, the Netherlands.
authors: Peter D
authors: PD
authors: Croughs
authors: Certe Laboratory for Infectious Diseases, Groningen, the Netherlands.
authors: Richard F
authors: RF
authors: de Boer
authors: Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands Certe Laboratory for Infectious Diseases, Groningen, the Netherlands.
authors: Anna M D
authors: AM
authors: Kooistra-Smid
authors: Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands j.rossen@umcg.nl.
authors: John W A
authors: JW
authors: Rossen
authors: Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
authors: Alexander W
authors: AW
authors: Friedrich
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics; D001435:Bacteriophages / Q000235:genetics*; D054308:Enteropathogenic Escherichia coli / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology; D019453:Escherichia coli O157 / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics; D005243:Feces / Q000382:microbiology; D036781:Fimbriae Proteins / Q000172:deficiency* / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D058889:Molecular Typing; D009426:Netherlands; D022621:Shiga Toxin / Q000235:genetics*; D013012:Sorbitol / Q000378:metabolism; D037521:Virulence Factors / Q000172:deficiency* / Q000235:genetics
chemical_list: D018829:Adhesins, Bacterial; C104901:BfpA protein, E coli; D029968:Escherichia coli Proteins; D037521:Virulence Factors; D036781:Fimbriae Proteins; D013012:Sorbitol; D022621:Shiga Toxin