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Streptococcus suis is a lethal pathogen in snakeskin gourami Trichopodus pectoralis
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Document Title
Streptococcus suis is a lethal pathogen in snakeskin gourami Trichopodus pectoralis
Author
Dinh-Hung N. Dong H.T. Taengphu S. Soontara C. Rodkhum C. Senapin S. Chatchaiphan S.
Affiliations
The International Graduate Program of Veterinary Science and Technology (VST) Faculty of Veterinary Science Chulalongkorn University Bangkok Thailand; Center of Excellence in Fish Infectious Diseases (CE FID) Department of Veterinary Microbiology Faculty of Veterinary Science Chulalongkorn University Bangkok Thailand; Department of Food Agriculture and Bioresources Aquaculture and Aquatic Resources Management Program Asian Institute of Technology (AIT) School of Environment Resources and Development Klong Luang Pathum Thani Thailand; Fish Heath Platform Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp) Faculty of Science Mahidol University Bangkok Thailand; National Center for Genetic Engineering and Biotechnology (BIOTEC) National Science and Technology Development Agency (NSTDA) Pathum Thani Thailand; Department of Aquaculture Faculty of Fisheries Kasetsart University Bangkok Thailand
Type
Article
Source Title
Aquaculture
ISSN
448486
Year
2023
Volume
566
Open Access
All Open Access Green
Publisher
Elsevier B.V.
DOI
10.1016/j.aquaculture.2022.739173
Abstract
The objective of this study was to determine the causative agent of an outbreak with clinical signs similar to those of piscine streptococcosis in farmed snakeskin gourami (Trichopodus pectoralis). Initial microscopic examination revealed the predominance of a Gram-positive cocci bacteria in the brain and kidney of the diseased fish. This bacterium was successfully isolated and identified as Streptococcus suis based on nucleotide homology of 16S rRNA and species-specific PCR. This isolate tested negative for Streptococcus suis serotype 2 which is an important zoonotic pathogen worldwide. Experimental infection was then performed to investigate the pathogenicity of the bacterium and its histopathological manifestation. Na?ve juvenile and adult snakeskin gourami were injected intraperitoneally with a low dose (1.2 ? 105 CFU/fish) and a high dose (1.2 ? 107 CFU/fish) of S. suis. Cumulative mortality appeared to be dose- and size-dependent. Experimentally diseased fish exhibited clinical signs consistent with naturally diseased fish. Severe histopathological changes in multiple organs were observed in both juvenile and adult fish including meningitis severe congestion in the brain and eyes thickened stromal layers of the retina severe hepatic lipidosis and tissue degeneration. Notably numerous granulomas containing massive bacterial cells in the necrotic core were observed in the infected fish. Relatively pure colonies of S. suis were recovered from tissues of experimentally diseased fish. Taken together this study fulfilled Koch s postulates indicating that S. suis is a new piscine pathogen. Although this is a case report public awareness and biosecurity measures should be considered to prevent the spread of the disease. Further surveillance of the pathogen s distribution and research into the underlying causes of fish-host adaptation will provide insights into the genuine impact of this bacterium in aquaculture and appropriate disease control strategies. ? 2022 Elsevier B.V.
Industrial Classification
Knowledge Taxonomy Level 1
Knowledge Taxonomy Level 2
Knowledge Taxonomy Level 3
License
Copyright
Rights
Elsevier B.V.
Publication Source
WOS