CHEMOTHERAPY OF CYTOPHAGA FLEXIBACTER-LIKE BACTERIA (CFLB) INFECTIONSIN FISH - STUDIES VALIDATING CLINICAL EFFICACIES OF SELECTED ANTIMICROBIALS/

In vitro and in vivo efficacies of commonly used chemotherapeutants we re determined for Cytophaga johnsonae, Cytophaga psychrophila, Flexiba cter columnaris and Flexibacter maritimus. Treatment of barramundi, La tes calcarifer (Bloch), with oxolinic acid (OA) as a bath (50 ppm) or by mouth (10 mg kg(-1) body weight) resulted in serum levels above the minimum inhibitory concentration (MIG) for F. columnaris and produced significant clinical efficacy (P < 0.05). Amoxycillin (AM) was found to produce adequate serum levels against F. maritimus when used as a b ath (200 ppm) or given orally (80 mg kg(-1) body weight) to Atlantic s almon, Salmo salar L. and rainbow trout, Oncorhynchus mykiss (Walbaum) , respectively. At these dose rates, this antibiotic was also clinical ly efficacious against F. maritimus (P < 0.05). Trimethoprim produced more than adequate serum levels for the control of F. maritimus when g iven as a bath (50 ppm) or orally (10 mg kg(-1) body weight). Trimetho prim was significantly more protective than AM when tested in vivo (P < 0.05). For C. johnsonae and C. psychrophila, the MIC values for OA a nd oxytetracycline were low, whereas that for TMP was high. Also, base d on MIC values, C. psychrophila strains were more sensitive to AM and norfloxacin than C. johnsonae.