BATH TREATMENT, AN ALTERNATIVE METHOD FOR THE ADMINISTRATION OF THE QUINOLONES FLUMEQUINE AND OXOLINIC ACID TO HALIBUT HIPPOGLOSSUS-HIPPOGLOSSUS, AND IN-VITRO ANTIBACTERIAL ACTIVITY OF THE DRUGS AGAINST SOME VIBRIO SP

Administration of flumequine and oxolinic acid to halibut Hippoglossus hippoglossus by bath resulted in significant tissue levels of both th e antibacterials. Bath treatment using 150 mg l(-1) of flumequine and 200 mg l(-1) of oxolinic acid for 72 h resulted in flumequine concentr ations of 14.2 mu g g(-1) in muscle and 85.4 mu g g(-1) in abdominal o rgan homogenate and oxolinic acid concentrations of 9.4 mu g g(-1) in muscle and 72.6 mu g g(-1) in abdominal organ homogenate. Excretion of both antibacterials was rapid and characterised by elimination half-l ives (t(1/2)) of 10 and 15.6 h respectively for flumequine and oxolini c acid in muscle and 9.8 and 15.0 h respectively in the abdominal orga n homogenate. The corresponding elimination times (E(t)) were 6.5 and 8 d respectively for flumequine and oxolinic acid in muscle and 7.5 an d 9 d respectively in abdominal organ homogenate when a maximum residu e concentration of 0.05 mu g g(-1) was applied for both drugs. The min imum inhibitory concentration (MIG) against strains of Vibrio sp. rang ed from 0.015 to 1.0 mu g ml(-1) for flumequine and 0.015 to 0.5 mu g ml-l for oxolinic acid. Following bath treatment, tissue levels of flu mequine and oxolinic acid greater than MIC for susceptible strains (<0 .0625 mu g ml(-1)) were maintained for up to 6.5 and 8 d respectively for flumequine and oxolinic acid in muscle and 7.5 and 9 d respectivel y in abdominal organ homogenate.