ABSTRACT: Administration of flumequine and oxolinic acid to halibut Hippoglossushippoglossus by bath resulted in significant tissue levels of both the antibacterials. Bath treatment using 150 mg l^-1 of flumequine and 200 mg l^-1 of oxolinic acid for 72 h resulted in flumequine concentrations of 14.2 µg g^-1 in muscle and 85.4 µg g^-1 in abdominal organ homogenate and oxolinic acid concentrations of 9.4 µg g^-1 in muscle and 72.6 µg g^-1 in abdominal organ homogenate. Excretion of both antibacterials was rapid and characterised by elimination half-lives (t_1/2) of 10 and 15.6 h respectively for flumequine and oxolinic acid in muscle and 9.8 and 15.0 h respectively in the abdominal organ homogenate. The corresponding elimination times (E_t) were 6.5 and 8 d respectively for flumequine and oxolinic acid in muscle and 7.5 and 9 d respectively in abdominal organ homogenate when a maximum residue concentration of 0.05 µg g^-1 was applied for both drugs. The minimum inhibitory concentration (MIC) against strains of Vibrio sp. ranged from 0.015 to 1.0 µg ml^-1 for flumequine and 0.015 to 0.5 µg ml^-1 for oxolinic acid. Following bath treatment, tissue levels of flumequine and oxolinic acid greater than MIC for susceptible strains (<0.0625 µg 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 respectively in abdominal organ homogenate.

KEY WORDS: Halibut · Bath treatment · Quinolones · Antibacterial activity

Published in DAO Vol. 27, No. 1 (1996) on October 17
ISSN: 0177-5103. Copyright © Inter-Research, Oldendorf/Luhe, 1996