In vitro antibacterial activity of florfenicol against Actinobacillus pleuropneumoniae.

A total of 90 strains of Actinobacillus pleuropneumoniae isolated from porcine pneumonic lungs in Japan during 1989 to 1993 were investigated for their in vitro susceptibility to florfenicol (a derivative of thiamphenicol) and other drugs. The minimal inhibitory concentrations of florfenicol against A. pleuropneumoniae ranged from 0.2 to 1.56 micrograms/ml with a peak at 0.39 microgram/ml. Florfenicol showed a high antibacterial activity against A. pleuropneumoniae regardless of the sensitivity of the strains to thiamphenicol.