Susceptibility of selected freshwater fish species to a UK Lactococcus garvieae isolate

• Published in: Journal of fish diseases 2009-10, Vol.32 (10), p.825-834
• Main Authors: Algöet, M, Bayley, A.E, Roberts, E.G, Feist, S.W, Wheeler, R.W, Verner-Jeffreys, D.W
• Format: Article
• Language: English
• Subjects: Animals; biological resistance; Brackish; Colony Count, Microbial - veterinary; Cyprinidae; cyprinids; Disease Susceptibility - immunology; Disease Susceptibility - microbiology; Disease Susceptibility - veterinary; Electrophoresis, Gel, Pulsed-Field - veterinary; Fish Diseases - immunology; Fish Diseases - microbiology; Fish Diseases - transmission; Freshwater; Gram-Positive Bacterial Infections - immunology; Gram-Positive Bacterial Infections - microbiology; Gram-Positive Bacterial Infections - transmission; Gram-Positive Bacterial Infections - veterinary; Lactococcus - immunology; Lactococcus - pathogenicity; Lactococcus garvieae; Marine; Oncorhynchus mykiss; pulsed field gel electrophoresis; Salmo salar; Salmo trutta; salmonid; Salmonidae; Serotyping - veterinary; Survival Analysis; susceptibility; Temperature; transmission; United Kingdom; Virulence
• ISSN: 0140-7775; 1365-2761
• DOI: 10.1111/j.1365-2761.2009.01058.x

Gram-positive cocci recovered from diseased rainbow trout from a farm in England were characterized by different methods, including pulsed field gel electrophoresis, as virulent Lactococcus garvieae serogroup 2 (pulsotype A1). Groups of rainbow trout were kept at a range of temperatures and injected intraperitoneally (i.p.) with one of the UK isolates, L. garvieae 00021. The 18 °C and 16 °C groups showed 67% and 28% mortality, respectively, by day 27 post-injection. Fish kept at 14 °C or lower were less susceptible ([less-than or equal to]3% mortality). Raising the temperature of all groups to 18 °C at day 27 post-injection did not result in recurrence of the disease, even though viable bacteria were recovered from all groups 42 days later. Grayling were highly susceptible, with 65% mortalities when challenged with 200 colony forming unit fish⁻¹ by i.p. injection and 37% mortalities when exposed to effluent water from tanks containing affected rainbow trout. Other fish species tested, Atlantic salmon, brown trout and seven cyprinid species, were less susceptible. Viable L. garvieae was isolated from the internal organs of all species tested at the end of the trials, suggesting that they may pose a threat as possible carriers to susceptible farmed and wild fish.