Genetic and serological diversity of Flavobacterium psychrophilum isolates from salmonids in United Kingdom

• Published in: Veterinary Microbiology
• Main Authors: Ngo, Thao P H, Bartie, Kerry, Thompson, Kim D, Verner-Jeffreys, David W, Hoare, Rowena, Adams, Alexandra
• Other Authors: European Commission, University of Stirling, Institute of Aquaculture, The Moredun Research Institute, CEFAS - Centre for Environment, Fisheries and Aquaculture Science, orcid:0000-0003-3037-5295, orcid:0000-0002-9298-4275
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2017
• Subjects: Rainbow trout fry syndrome; Bacterial cold water disease; Flavobacterium psychrophilum; Genotyping; Serotyping; Plasmids; Atlantic salmon
• Online Access: http://hdl.handle.net/1893/24981; https://doi.org/10.1016/j.vetmic.2017.01.032; http://dspace.stir.ac.uk/bitstream/1893/24981/1/Manuscript%20%28revised%29.pdf

Flavobacterium psychrophilumis one of the most important bacterial pathogens affecting cultured rainbow trout (Oncorhynchus mykiss) and is increasingly causing problems in Atlantic salmon (Salmo salarL.) hatcheries. Little is known about the heterogeneity of F. psychrophilumisolates on UK salmonid farms. A total of 315 F. psychrophilumisolates, 293 of which were collected from 27 sites within the UK, were characterised using four genotyping methods and a serotyping scheme. A high strain diversity was identified among the isolates with 54 pulsotypes, ten (GTG)5-PCR types, two 16S rRNA allele lineages, seven plasmid profiles and three serotypes. Seven PFGE groups and 27 singletons were formed at a band similarity of 80%. PFGE group P (n=75) was found to be numerically predominant in eight sites within the UK. Two major PFGE clusters and 13 outliers were found at the band similarity of 40%. The predominant profile observed within the F. psychrophilumisolates examined was PFGE cluster II − (GTG)5-PCR type r1–16S rRNA lineage II − serotype Th (70/156 isolates examined, 45%). Co-existence of genetically and serologically heterogeneous isolates within each farm was detected, confounding the ability to control RTFS outbreaks. The occurrence over time (up to 11 years) of F. psychrophilumpulsotypes in three representative sites (Scot I, Scot III and Scot V) within Scotland was examined, potentially providing important epidemiological data for farm management and the development of site-specific vaccines.