Administration of the antibacterial agents flumequine and oxolinic acid to small turbot (Scophthalmus maximus L.) by bath

Administration of flumequine and oxolinic acid to turbot, Scophthalmus maximus L., by bath resulted in significant levels of both drugs in the muscle tissue. Bath treatment using 150 mg L−1 of flumequine and 200 mg L−1 of oxolinic acid for 72 h gave muscle concentrations of 10.2 and 6.2 μg g−1, respectively. Excretion of both antibacterials was rapid, reaching concentrations of 0.8 and 0.9 μg g−1, respectively, for flumequine and oxolinic acid 24 h after the end of treatment. At day 3 post-treatment the concentration of flumequine was below the limit of quantitation (0.1 μg g−1) of the analytical method. Based on a minimum inhibitory concentration (MIC) of 0.0625 μg ml−1 for susceptible strains, bath treatment maintain muscle levels in excess of 0.5 μg ml−1, corresponding to eight times the MIC-value for approximately 118 h for oxolinic acid and 104 h for flumequine.