title: Association of Flavobacterium psychrophilum strains with intestinal explants of rainbow trout Oncorhynchus mykiss.
abstract: Flavobacterium psychrophilum is an important pathogen in rainbow trout Oncorhynchus mykiss. The portal of entry for F. psychrophilum is not well known. In this study, the role of the intestine as a colonization site for F. psychrophilum was determined. For this purpose, the ability of a high (Dubois) and a low (99/10A) virulence strain of F. psychrophilum to adhere to intestinal explants of rainbow trout was evaluated. After incubation, samples of the gut were examined bacteriologically, histologically and by electron microscopy. The number of gut-associated F. psychrophilum bacteria was significantly higher for the Dubois than for the 99/10A strain. Histological samples clearly showed numerous bacteria of the high virulence strain associated with the intestinal tissue as opposed to only a few bacteria of the low virulence strain. Additionally, extensive exfoliation of intestinal epithelium was noted after incubation with the high virulence strain, but less with the low virulence strain. These findings were confirmed using scanning electron microscopy and suggest that the intestinal epithelium might represent an important site for colonization of the F. psychrophilum strain and may act as a portal of entry for high virulence F. psychrophilum.
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. anematolahi@yahoo.com
authors.forename: Amin
authors.initials: A
authors.lastname: Nematollahi
authors.forename: Frank
authors.initials: F
authors.lastname: Pasmans
authors.forename: Wim
authors.initials: W
authors.lastname: Van den Broeck
authors.forename: Richard
authors.initials: R
authors.lastname: Ducatelle
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
authors.forename: Annemie
authors.initials: A
authors.lastname: Decostere
mesh_terms: D000818:Animals; D005417:Flavobacterium / Q000235:genetics / Q000472:pathogenicity*; D007413:Intestinal Mucosa / Q000382:microbiology* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D017686:Oncorhynchus mykiss / Q000382:microbiology*; D013045:Species Specificity; D014774:Virulence