Modern Trends in Aeromonas hydrophila Disease Management with Fish.

Aeromonas hydrophila, a ubiquitous, free-living, Gram-negative bacterium, is prevalent in aquatic habitats with cosmopolitan distribution; it is an opportunistic pathogen that has resulted in heavy mortalities in farmed and feral fishes. The traditional application of antibiotics and chemotherapy has been characterized by partial success in the management of diseases like motile aeromonad septicemia (MAS) and aeromonad-associated diseases like epizootic ulcerative syndrome (EUS). Application of antibiotics and chemotherapeutic drugs are necessary in the disease management though this practice has triggered the emergence of drug resistant strains in pathogens. Further resistance may be transferred to other related or unrelated bacteria; therefore, it is necessary to develop and screen new chemicals. Disease prevention by means of vaccination and immuno-stimulation of fish in aquaculture has been particularly successful against several bacterial diseases. For example, mono and multivalent vaccines have been developed against several bacterial diseases in fish. However, when new diseases and pathogens emerge from time to time, it would be difficult to develop such proactive strategies quickly. Recently, probiotics are widely used in aquaculture since they produce bacteriocins and other chemical compounds inhibiting the growth of pathogenic bacteria. Another emerging trend is medicinal plant research, which has increased the world over since herbs used in traditional medicine have little side effects are easily biodegradable and abundantly available in farm areas free of cost. Some herbals that wield potent antibacterial activity against shrimp and fish bacterial pathogens have a crucial role in disease management. Indeed, application of probiotics and herbals in aquaculture may also reduce cost of disease management by obviating the expenses incurred by the use of antibiotics, chemicals, and vaccinations in the future. [ABSTRACT FROM AUTHOR]