Practical management of bacterial diseases in finfish aquaculture to minimise antimicrobial resistance

Abstract

The development of drug-resistant strains of bacterial pathogens of fish threatens the efficacy of limited aquaculture approved drugs. Development of antimicrobial resistance (AMR) is a natural process in resident bacteria in the environment. Any time antibiotics are used in an aquaculture facility it provides a competitive advantage for pathogens with AMR. This results in a build-up of drug-resistant fish pathogens. Aquaculturists can minimise the build-up of AMR pathogens by reducing the frequency of antibiotic applications and by making sure the antibiotic is properly applied it is when needed. Management practices that reduce antibiotic use are the most important strategies to avoid the build-up of AMR. Disease prevention is a continuous process in all stages of planning and all phases of production. It involves site and strain selection, managing the environment and handling to minimise stress, controlling the feed, using effective vaccines, and applying biosecurity. An effective antibiotic treatment regimen must provide the therapeutic dose and persistence needed to kill the bacteria. When using medicated feed, the fish must still be eating well and the incorporated antibiotic must be of good quality and at the proper dose determined by the weight of the fish. The antibiotic must be provided for the prescribed time even after fish mortality has stopped. Management to reduce the persistence of AMR pathogens also assures that antibiotics will be effective when needed.