Isolation and characterization of Lactococcus garvieae from rainbow trout, Onchorhyncus mykiss, from California, USA.

Autor: Shahin K; Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA.; Aquatic Animal Diseases Laboratory, Aquaculture Department, National Institute of Oceanography and Fisheries, Suez, Egypt., Veek T; California Department of Fish and Wildlife, Rancho Cordova, California, USA., Heckman TI; Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA., Littman E; Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA., Mukkatira K; California Department of Fish and Wildlife, Rancho Cordova, California, USA., Adkison M; California Department of Fish and Wildlife, Rancho Cordova, California, USA., Welch TJ; National Center for Cool and Coldwater Aquaculture, Kearneysville, West Virginia, USA., Imai DM; Comparative Pathology Laboratory, School of Veterinary Medicine, University of California, Davis, California, USA., Pastenkos G; Comparative Pathology Laboratory, School of Veterinary Medicine, University of California, Davis, California, USA., Camus A; Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA., Soto E; Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA.
Jazyk: angličtina
Zdroj: Transboundary and emerging diseases [Transbound Emerg Dis] 2022 Jul; Vol. 69 (4), pp. 2326-2343. Date of Electronic Publication: 2021 Aug 25.
DOI: 10.1111/tbed.14250
Abstrakt: Lactococcus garvieae is an emergent bacterial pathogen of salmonid fish in North America that causes acute infections particularly at water temperatures above 15°C. During 2020, L. garvieae was detected in rainbow trout, Onchorhyncus mykiss, cultured in Southern California and the Eastern Sierras. Infected fish exhibited high mortalities and nonspecific clinical signs of lethargy, erratic swimming, dark skin pigmentation, and exophthalmia. Macroscopic changes included external and internal hemorrhages, mainly in the eyes, liver, coelomic fat, intestine, and brain. Histological examination revealed splenitis, branchitis, panophthalmitis, hepatitis, enteritis, and coelomitis, with variable degrees of tissue damage among evaluated fish. Pure colonies of L. garvieae were isolated from infected trout and specific PCR primers for L. garvieae confirmed the preliminary diagnosis. Multilocus sequence analysis showed that the strains recovered from diseased trout represent a novel genetic group. Isolates were able to form biofilms within 24 h that increased their resistance to disinfection by hydrogen peroxide. Laboratory challenge methods for inducing lactococcosis in steelhead trout, O. mykiss, were evaluated by intracoelomic injection with serial dilutions of L. garvieae. The median lethal dose 21 days post challenge was ∼20 colony-forming units/fish. Experimentally infected trout presented similar clinical signs, gross changes, and microscopic lesions as those with natural disease, fulfilling Koch's postulates and demonstrating the high virulence of the recovered strains.
(© 2021 Wiley-VCH GmbH.)
Databáze: MEDLINE
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