Antibiotics remain a critical tool in controlling bacterial diseases in commonly cultured species. However, certain limitations on the long-term feasibility of antibiotic use exist. Only three antibiotics are FDA approved for use in cultured finfish: oxytetracycline, florfenicol, and sulfadimethoxine. Even these three approved drugs can only be applied in specified cultured species when infected with certain bacterial agents. Moreover, these approved antibiotics are exclusively administered via medicated feeds with the exception of oxytetracycline. Given that bacterial agents often lower appetence in cultured finfish, oral administration may not prove effective. Additionally, antimicrobial resistance continues to occur despite steps taken to prevent its development. For these reasons, producers and veterinarians alike should reevaluate alternatives to antibiotic use in the aquaculture setting.
Novel therapies post-infection pose promising yet poorly underdeveloped methods to counteract bacterial agents. Bacteriophage and immunomodulatory therapies can be tailored to the bacterial species of concern. The targeted nature of these two therapies may confer a more precise treatment for the infection, but such an individualized approach may hamper widespread adoption in the industry. Prebiotics, probiotics, and phytobiotics may be utilized to address outbreaks, as these therapies alter multiple host pathways to discourage bacterial growth. While these three treatments show potential for development, their mechanisms of action are poorly understood even in human medicine. It should be noted that all novel therapies will suffer from many of the same problems antibiotics exhibit: prolonged FDA approval and limited routes of administration.
Previously established alternatives to antibiotic use primarily center on preventative medicine. Biosecurity protocols are vital to minimizing the introduction and proliferation of bacterial diseases at individual operations. Vaccination, while not yet mainstream, has proven effective in preventing economically disastrous outbreaks at larger farms. The industry should continue to emphasize such preventative measures because discouraging outbreaks suppresses the overuse of antibiotics and provides cost savings to farms. Finally, preventative steps represent the most practical alternatives to antibiotics in the near term given that novel therapies require lengthy FDA approval.