In vitro antibacterial activities and postantibiotic effects of marbofloxacin against main marine pathogenic Vibrios

Susceptibilities,minimal inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of marbofloxacin against Vibrio alginolyticus,V.harveyi,V.fischeri and V.splendidus were respectively determined by means of oxford cup and twofold dilution methods,and were compared with those of other four antimicrobial drugs including difloxacin,enrofloxacin,norfloxacin and florfenicol.Postantibiotic effects (PAEs) of marbofloxacin against Vibrio alginolyticus,V.harveyi and V.splendidus were also determined by colony counting method.The results showed that the in vitro antibacterial activity of marbofloxacin against the four marine pathogenic vibrios was similar to that of florfenicol,but more potent than those of difloxacin,enrofloxacin and norfloxacin.It was shown that,at the concentrations of 1×MIC,2×MIC and 4×MIC,the PAEs of marbofloxacin against Vibrio alginolyticus,V.harveyi and V.splendidus were 0.49 h,0.87 h and 1.17 h;0.64 h,0.98 h and 1.22 h;0.75 h,1.02 h and 1.25 h;respectively,which showed that the postantibiotic effect of marbofloxacin against Vibrio alginolyticus,V.harveyi and V.splendidus was significant,and that the PAE value will increase with the drug concentrations increasing.