title: Adhesion of marine cryptic Escherichia isolates to human intestinal epithelial cells.
abstract: Five distinct cryptic lineages (clades I-V) have recently been recognized in the Escherichia genus. The five clades encompass strains that are phenotypically and taxonomically indistinguishable from Escherichia coli sensu stricto; however, scant data are available on their ecology, virulence and pathogenic properties. In this study 20 cryptic E. coli strains isolated from marine sediments were investigated to gain insights into their virulence characteristics and genetic traits. The ability to adhere to intestinal cells was highest among clade V strains, which also harbored the genes involved in gut colonization as well as the genes (pduC and eut operon) typically found in environmentally adapted E. coli strains. The pduC gene was significantly associated with clade V. Multilocus sequence typing of three representative clade V isolates revealed new sequence types (STs) and showed that the strains shared two allelic loci (adk 51 and recA 37). Our findings suggest that cryptic Escherichia lineages are common in coastal marine sediments and that this habitat may be suitable for their growth and persistence outside the host. On the other hand, detection in clade V strains of a gene repertoire and adhesion properties similar to those of intestinal pathogenic strains could indicate their potential virulence. It could be argued that there is a dual nature of cryptic clade V strains, where the ability to survive and persist in a secondary habitat does not involve the loss of the host-associated lifestyle. Clade V could be a group of closely related, environmentally adapted E. coli strains.
authors.affiliation: Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Vignaroli
authors.affiliation: Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Di Sante
authors.affiliation: Department of Biomedical Sciences and Public Health, Polytechnic University of Marche, Ancona, Italy.
authors.forename: Gloria
authors.initials: G
authors.lastname: Magi
authors.affiliation: Institute of Marine Sciences-National Research Council (ISMAR-CNR), Venezia, Italy.
authors.forename: Gian Marco
authors.initials: GM
authors.lastname: Luna
authors.affiliation: 1] Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy [2] Institute of Ecosystem Study-National Research Council (ISE-CNR), Verbania, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Di Cesare
authors.affiliation: Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Pasquaroli
authors.affiliation: Department of Biomedical Sciences and Public Health, Polytechnic University of Marche, Ancona, Italy.
authors.forename: Bruna
authors.initials: B
authors.lastname: Facinelli
authors.affiliation: Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Biavasco
mesh_terms: D001422:Bacterial Adhesion; D004847:Epithelial Cells / Q000382:microbiology*; D004926:Escherichia coli / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology*; D058885:Multilocus Sequence Typing; D014774:Virulence / Q000235:genetics