title: In vivo adherence of Flavobacterium psychrophilum to mucosal external surfaces of rainbow trout (Oncorhynchus mykiss) fry.
abstract: The adherence of Flavobacterium psychrophilum to surfaces of epithelial tissues has been inconclusively suggested as a mechanism, which enables the bacterium to invade the host. Hence, the present study aimed to examine the adherence of the cells of two colony phenotypes, smooth and rough, of F. psychrophilum to mucosal tissues of rainbow trout fry and to test the skin mucus as a nutrient for the growth of F. psychrophilum. Fish were immersed in water containing 106CFUmL-1F. psychrophilum for each colony phenotype. Mucosal tissue samples from fins, gills, skin and eyes, and swab samples from spleen and kidney were taken and inoculated onto TYES agar plates. Colony phenotypes of F. psychrophilum were identified and number of colonies counted. The results showed that cells of both phenotypes initially (0 h) adhered to all mucosal surfaces, but only the rough cells were still present on tissues 1 h post-immersion. Both phenotypes showed a tissue tropism with the fin tissue being the most adhered. Furthermore, skin mucus promoted the growth of both colony phenotypes. We suggest that the growth of F. psychrophilum cells in skin mucus apparently facilitates the bacterial adherence to mucosal surfaces, and the subsequent invasion into the host.
authors.affiliation: Laboratory of Aquatic Pathobiology, Environmental and Marine Biology, Åbo Akademi University, Turku, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Papadopoulou
authors.affiliation: National Veterinary Institute, Technical University of Denmark, Frederiksberg C, Denmark.
authors.forename: I
authors.initials: I
authors.lastname: Dalsgaard
authors.affiliation: Coastal Zone Research Team, Novia University of Applied Sciences, Ekenäs, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Lindén
authors.affiliation: Laboratory of Aquatic Pathobiology, Environmental and Marine Biology, Åbo Akademi University, Turku, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Wiklund
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D005393:Fish Diseases / Q000382:microbiology*; D045826:Flavobacteriaceae Infections / Q000382:microbiology / Q000662:veterinary*; D005417:Flavobacterium / Q000235:genetics / Q000502:physiology*; D009092:Mucous Membrane / Q000382:microbiology; D009093:Mucus / Q000382:microbiology; D017686:Oncorhynchus mykiss; D010641:Phenotype
keywords: 
  Flavobacterium psychrophilum
  ; adherence; rainbow trout; skin mucus; smooth and rough colony phenotypes