Abstract
The experiment was designed to examine the application of trimethoprim (TMP) and sulfonamides (SA) as therapeutical agents for vibriosis in ayu, Plecoglossus altivelis. Microbiological evaluation was made for TMP and SA in alone and combined on the causative agent Vibrio anguillarum in comparison with some known chemotherapeutic agents. Antimicrobial activity in vitro and therapeutical effect in vivo were also observed for ayu infected experimentally and naturally. Results obtained are following:
1. In the antimicrobial activity, TMP was superior to other drugs, chloramphenicol, tetracycline, nitrofurazone and nalidixic acid against drug-resistant V. anguillarum strains. Synergism of TMP and SA was clearly obtain on SA-sensitive strains in vitro.
2. V. anguillarum growing in broth containing the rising concentration of TMP-SA increased resistance in 2 to 8-fold after 10 transfers, even in the strains of SA-sensitive.
3. Therapeutic effect of TMP on the diseased fish; TMP was effective on vibriosis which was caused experimentally and naturally by the drug-resistant strain of V. anguillarum.
