Investigation of the Pathobiology of Edwardsiella piscicida—Septicemia in Largemouth Bass

<i>Edwardsiella piscicida</i> septicemia is a significant threat to aquaculture, causing substantial production and economic losses. The causative bacterium <i>E. piscicida</i> infects multiple fish species of aquaculture relevance. This study investigated the pathogenicity of catfish-derived <i>E. piscicida</i> in largemouth bass (<i>Micropterus salmoides</i>) fingerlings. The experimental infection of largemouth bass using genotypically distinct <i>E. piscicida</i> isolates resulted in significant fish mortality independent of the isolate genotypes. A specific correlation between discrete <i>E. piscicida</i> 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 <i>E. piscicida</i> isolates in largemouth bass fingerlings, which could be crucial in developing effective pathogen-targeted management strategies to combat a deadly disease.