ANTIBIOTIC SUSCEPTIBILITIES OF BACTERIA ISOLATED FROM THE SAME FISH IN CASES EXAMINED AT THE KENTUCKY STATE UNIVERSITY FISH DISEASE DIAGNOSTIC LABORATORY

This study analyzes differences in antibiotic susceptibilities among isolated bacterial colonies of the same species from a single fish from 10 different cases diagnosed at the KSU Fish Disease Diagnostic Laboratory (FDDL). For each case, four identical bacterial colonies isolated from a single fish will be tested for susceptibility to oxytetracycline, florfenicol and sulfadimethoxine + ormetoprim antibiotics. It is hypothesized that consistency in susceptibilities to all three antibiotics will be found among all four isolates from the same fish. In other words, if one isolate of the same bacterial species from one fish is sensitive to all three antibiotics, then the other three isolates will also be sensitive to them. This would give credibility to recommendations made by FDDL to use these antibiotics when treating for the infection with medicated feed. If, on the other hand, differences exist in antibiotic susceptibilities among bacterial isolates (with the same identification) from the same fish, then confidence in FDDL recommendations would be compromised. In other words, antibiotic susceptibility results would be dependent on which bacterial isolate happened to be chosen, and results would not have been the same if another isolate had been chosen. Results of this study will either confirm/validate FDDL protocols (especially if consistency in antibiotic susceptibilities is found among bacterial isolates) or show that FDDL protocols may need to be modified to achieve more accurate and consistent results in antibiotic susceptibilities and subsequent recommendations to our laboratory clientele to treat with medicated feeds containing these antibiotics.