Investigation of the pathobiology of Edwardsiella piscicida – septicemia in largemouth bass

Authors: RAMENA, GRACE - University Of Arkansas At Pine Bluff; Aarattuthodi, Suja; SRIRAMOJU, GNANENDER - University Of Arkansas At Pine Bluff; RAMENA, YATISH - University Of Arkansas At Pine Bluff

Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2025
Publication Date: 3/31/2025
Citation: Ramena, G., Aarattuthodi, S., Sriramoju, G., Ramena, Y. 2025. Investigation of the pathobiology of Edwardsiella piscicida – septicemia in largemouth bass. Pathogens. https://doi.org/10.3390/pathogens14040334.
DOI: https://doi.org/10.3390/pathogens14040334

Interpretive Summary: Edwardsiella piscicida is a virulent pathogen causing E. piscicida-septicemia in several freshwater and marine fish species, posing a major threat to global aquaculture. The wide host range and geographical distribution of E. piscicida pose it as one of the most economically devastating pathogens. Largemouth bass is an important food and sportfish species in the U.S. with over 200 farms spread over 32 states, with the industry generating ~$200 million annually. With the current intensification of aquaculture practices, disease-related losses can be substantial. Although some effective antibiotics are available, regulatory restrictions associated with antimicrobial resistance and the cost-prohibitive nature of medicated feed make those infeasible for disease management. Study results indicated that the catfish-originated E. piscicida isolates caused significant mortality in largemouth bass. Specific correlation among distinct E. piscicida genotypes and fish mortalities was not identified. Understanding the pathogenicity of various E. piscicida strains in commercially important fish species will facilitate the development of effective and economically pragmatic pathogen-targeted management strategies to limit the impacts of E. piscicida on aquaculture.

Technical Abstract: Edwardsiella piscicida septicemia is a significant threat to aquaculture, causing substantial production and economic losses. The causative bacterium E. piscicida infects multiple fish species of aquaculture relevance. This study investigated the pathogenicity of catfish-derived E. piscicida in largemouth bass (Micropterus salmoides) fingerlings. The experimental infection of largemouth bass using genotypically distinct E. piscicida isolates resulted in significant fish mortality independent of the isolate genotypes. A specific correlation between discrete E. piscicida genotypes and fish mortalities was not identified. The histopathological assessment of tissues from infected fish revealed inflammatory lesions characteristic of bacterial septicemia. This study provides insights into the pathogenesis of heterologous E. piscicida isolates in largemouth bass fingerlings, which could be crucial in developing effective pathogen-targeted management strategies to combat a deadly disease.