Pharmacodynamics of Florfenicol on Bacterium Yersinia ruckeri in vitro

The pharmacodynamics of florfenicol on bacterium Yersinia ruckeri were studied in vitro including minimal inhibitory concentration(MIC);minimal bactericidal concentration(MBC);the growth curve of the bacterium;the bacteriocidal curve of the florfenicolandpost-antibioticeffec(t PAE).TheresultsshowedthattheflorfenicolhadMICof0.5μg·mL-1,MBCof1μg·mL-1 andMBC/MIC of2.The logarithmic growth phase was observed in the bacterium cultured in fluid medium for 1 hour and lasted about 7 hours.The florfenicol showed the maximum activity 4～6 hours after administration and was a dose-dependence by the bacteriocidal curve.The value of PAE were found to be 3.71±0.11 in 2 MIC,4.54±0.27 in 4 MIC,and 5.52±0.23 in 8 MIC.Florfenicol had the most effective inhibition of Y.ruckeri at pH 6~8.There was no significant impact of Mg 2+,serum content,and less than 10 8 of bacteria quantity on bactericidal activity of the florfenicol.Therefore,the maximal efficacy of florfenicol depends on dose,administration period and the optimal environmental factors.