Pathogenesis of gram-negative bacterial infections in warmwater fish

Abstract

Knowledge concerning the pathogenesis of many bacterial diseases in fish is limited, especially in those diseases that occur in warmwater species. This limited knowledge base is due to the relative recent emergence of warmwater fish culture as a major industry in many parts of the world, and to the previous economic insignificance of warmwater aquaculture and the bacterial pathogens affecting warmwater species. This article is an overview of the important gram-negative pathogens of warmwater fish, including members of the genera Aeromonas, Edwardsiella, Pasteurella, Pseudomonas, and Vibrio. The current knowledge of the pathogenesis of these organisms is emphasized, including: the source of the pathogen, its preferred site and method for attaching to and penetrating the host, its adaptations for surviving the host immune system, and its strategies for obtaining nutrients required for proliferation and growth. Although information for many of these pathogens is limited, the intent of this article is to provide a baseline for the development of future research projects. Increases in worldwide aquaculture production will result in a demand for knowledge about the pathogenesis of bacterial pathogens in warmwater fish, because of its importance in making health management decisions, in deciding on treatment regimens, and in the development of vaccines.