Antibacterial effect of chloramphenicol, thiamphenicol and florfenicol against aquatic animal bacteria

The minimum inhibitory concentration (MIC) was measured to evaluate the ant ibacterial activities of chloramphenicol (CP), thiamphenicol (TP) and florf enicol (EFC) against the aquatic bacterial isolates from soft-shell turtles , fish and shellfish. Amoxicillin (AMPC), oxytetracycline (OTC) and oxolini c acid (OA) were included to compare with above protein synthesis inhibitor s. The results showed that the order of MIC range of the isolates From soft -shell turtles for tested drugs was OA>FFC, CP>TP>AMPC, OTC. The percentage of the resistant strains indicated that OA was the lowest (7.14%) and OTC was the highest (85.07%). The order of antibacterial activity against the i solates from fish was OA>FFC>CP >AMPC>OTC>TP. The percentage of the resista nt strains revealed that OA (13.64%) and OTC (80.91%) were the lowest and t he highest, respectively. For the isolates from shellfish, the order of ant imicrobial activity was OA>CP, FFC>AMPC, OTC, TP. TP showed the greatest pe rcentage of the resistant strains (58.7%), but that of OA was the lowest (4 .35%). The most common resistant patterns of the isolates from turtles, fis h and shellfish were AMPC-OTC, CP-TP-AMPC-OTC, and FFC-CP-TP-AMPC-OTC, resp ectively. There were partially-complete resistance of the resistant isolate s among CP, TP and FFC. The findings indicated that previous treatment migh t affect the choice of drug to use for aquatic bacterial diseases.