In vitro combined effect of valnemulin with chlortetracycline against Pasteurella multocida, Actinobacillus pleuropneumoniae and Bordetella bronchiseptica

摘要

Pasteurella multocida, Actinobacillus pleuropneumoniae and Bordeiella bronchiseptica are a primaiy or frequently a secondary invader in pneumonia of swine, cattle, sheep, goats and others species. They are frequently involved in the enzootic pneumonia in swine, and have been shown to be resistant to wide range of beta- lactams, (etracycline, thiamphenicol and new quinolones. In Japan, drug resistance of P. multocida, A. pleuropneumoniae and B bronchiseptica has been observed in about 20 percent ofclinical isolates, posing a grave clinical problem. To over-come the situation, we checked the drug susceptibility of recent clinical isolates of P. multocida, A. pleuropneumoniae and?B. bronchiseptica. In addition, we investigated in vitro combined effects of valnemutin with chlortetracycline on P. multocida, A. pleuropneumoniae and 6. bronchiseptica by the checkerboard method and the combined effect of valnemulin with chlortetracycline on P. multocida by killing curve method. Valnemulin was obtained from S.D.S. Biotech and chlortetracycline was obtained from Wako pure chemical.MIC was determined by the agar dilution method, and in vitro combined effect of valnemulin and chlortetracycline was examined by the checkerboard method with serial 2-fold dilution. The effect of the drug combination was expressed as a FIC index.