Post-antibiotic effect of Florfenicol on pathogenic bacteria of eels in vitro

The post-antibiotic effect (PAE) of florfenicol on cardinal pathogenic bacteria of eels,including Enterobacter B01,Klebsiella B12,Aeromonas caviae B15,Aeromonas hydrophila B20,were determined in vitro.Dilution method was used to determine the MIC and MBC of florfenicol against these bacteria,and Mueller-Hinton agar colony counting method was used to monitor the growth of the bacteria.The results showed that marked PAE of florfenicol was found at the concentration of 0.5,1,2 and 4×MIC.The duration of PAE was enhanced with the increasing concentration.PAE against B01,B12,B15 and B20 was obviously prolonged,especially at 4×MIC,which was respectively up to 2.5±0.165,3.0±0.038,5.0±0.090 and 5.0±0.232 h.At the concentration of 2×MIC,PAE value of florfenicol against 4 kinds of bacteria had significant difference.At the concentration of 4×MIC,had no difference.At the same concentration,PAE value of florfenicol against B01 and B12 was obvious lower than that of B15 and B20.It is suggested that longer dosing interval should be recommended when florfenicol is used against eels' pathogenic bacteria,which achieved reducing side-effect on the growth and feed intake of eels.