title: Adhesive properties of Enterobacter sakazakii to human epithelial and brain microvascular endothelial cells.
abstract: BACKGROUND
  Enterobacter sakazakii is an opportunistic pathogen that has been associated with sporadic cases and outbreaks causing meningitis, necrotizing enterocolitis and sepsis especially in neonates. However, up to now little is known about the mechanisms of pathogenicity in E. sakazakii. A necessary state in the successful colonization, establishment and ultimately production of disease by microbial pathogens is the ability to adhere to host surfaces such as mucous membranes, gastric and intestinal epithelial or endothelial tissue. This study examined for the first time the adherence ability of 50 E. sakazakii strains to the two epithelial cell lines HEp-2 and Caco-2, as well as the brain microvascular endothelial cell line HBMEC. Furthermore, the effects of bacterial culture conditions on the adherence behaviour were investigated. An attempt was made to characterize the factors involved in adherence.
  
  
  RESULTS
  Two distinctive adherence patterns, a diffuse adhesion and the formation of localized clusters of bacteria on the cell surface could be distinguished on all three cell lines. In some strains, a mixture of both patterns was observed. Adherence was maximal during late exponential phase, and increased with higher MOI. The adhesion capacity of E. sakazakii to HBMEC cells was affected by the addition of blood to the bacteria growth medium. Mannose, hemagglutination, trypsin digestion experiments and transmission electron microscopy suggested that the adhesion of E. sakazakii to the epithelial and endothelial cells is mainly non-fimbrial based.
  
  
  CONCLUSIONS
  Adherence experiments show heterogeneity within different E. sakazakii strains. In agreement with studies on E. cloacae, we found no relationship between the adhesive capacities in E. sakazakii and the eventual production of specific fimbriae. Further studies will have to be carried out in order to determine the adhesin(s) involved in the interaction of E. sakazakii with cells and to enhance knowledge of the pathogenesis of E. sakazakii infection.
authors.affiliation: Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, CH-8057 Zurich, Switzerland. ils@fsafety.unizh.ch
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Mange
authors.forename: Roger
authors.initials: R
authors.lastname: Stephan
authors.forename: Nicole
authors.initials: N
authors.lastname: Borel
authors.forename: Peter
authors.initials: P
authors.lastname: Wild
authors.forename: Kwang Sik
authors.initials: KS
authors.lastname: Kim
authors.forename: Andreas
authors.initials: A
authors.lastname: Pospischil
authors.forename: Angelika
authors.initials: A
authors.lastname: Lehner
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism; D001422:Bacterial Adhesion / Q000502:physiology*; D001921:Brain / Q000166:cytology*; D018938:Caco-2 Cells; D044083:Cronobacter sakazakii / Q000737:chemistry / Q000502:physiology*; D003470:Culture Media; D042783:Endothelial Cells / Q000382:microbiology / Q000502:physiology*; D004730:Endothelium, Vascular / Q000382:microbiology / Q000502:physiology*; D006801:Humans
chemical_list: D018829:Adhesins, Bacterial; D003470:Culture Media