Best therapeutic practices for the use of antibacterial agents in finfish aquaculture: a particular view on European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) in Mediterranean aquaculture

Antibacterial therapy is still in many cases the only way to control bacterial disease outbreaks, with relevant economic issues. Nevertheless, this necessity should also be well balanced with other relevant aspects such as suitability, efficacy and refinement of the treatments but also with consumer and environmental welfare. With this aim, the literature pertaining to the use of antibacterials (i.e. oxytetracycline, oxolinic acid, flumequine and potentiated sulphonamides) in Mediterranean farmed European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) was reviewed and addressed. Knowledge of drug pharmacokinetics along with the related legislation is also presented. The main criteria, technical aspects and constraints affecting the design of an appropriate antibacterial therapy are also discussed. An evaluation of available bibliography revealed the existence of considerable information on several registered antibacterials, while it is limited for others. Typically, minimum inhibitory concentrations (MIC) have been used as a reference for antibacterial selection. However, the methodologies used for MIC assessment require refinement and more sophisticated data such as epidemiological cut-off breakpoint values. Due to the characteristics of farming systems, antibacterials are mostly delivered through medicated feeds. The large number of production units and number of fish per unit, together with a limited timeframe margin for efficient therapy, makes Mediterranean gilthead seabream and European seabass, one of the best examples where the metaphylactic concept has to be considered in aquatic medicine. The information presented in this review should guide future action taken to fulfil research gaps and promote effective and prudent antibacterial practices.