Infection models with Flavobacterium psychrophilum

High mortalities among rainbow trout (Oncorhynchus mykiss) fry are often the result of infections caused by Flavobacterium psychrophilum, and in Denmark this pathogen can be found in nearly all freshwater fish farms. The infection can be treated with antibiotics, but lower sensitivity against the infection is an increasing problem for some of the used drugs, wherefore alternative treatment methods (e.g. bacteriophages) are investigated. Prophylactic measures (e.g. feed additives) are another approach, so infections with the bacterium can be avoided, before they become a problem. No matter if the focus is on prophylactic or alternative treatment, reliable infection models are needed to evaluate the treatments as well as to get more knowledge about infections with F. psychrophilum. Experimental infection models will be presented, among them a reproducible intraperitoneal injection model as well as different bath models, and the potential for using the models will be discussed