ANTIMICROBIAL SUSCEPTIBILITY OF ACTINOBACILLUS-PLEUROPNEUMONIAE, PASTEURELLA-MULTOCIDA AND SALMONELLA-CHOLERAESUIS ISOLATES FROM PIGS

The in vitro susceptibility of 839 isolates of Actinobacillus pleuropn eumoniae, 969 isolates of Pasteurella multocida and 104 isolates of Sa lmonella choleraesuis from pigs to the fluoroquinolone danofloxacin, a nd eight other commonly used antimicrobial drugs was determined by vet erinary diagnostic laboratories in Europe, Japan, South Africa and Nor th America between 1989 and 1991, by using a broth microdilution techn ique. The minimum inhibitory concentrations of danofloxacin, amoxycill in, ceftiofur, erythromycin, gentamicin, lincomycin, oxytetracycline, spectinomycin and trimethoprim: sulphamethoxazole (ratio 1:19) that pr evented the growth of 90 per cent of the bacteria were 0.125, less-tha n-or-equal-to 0.5, less-than-or-equal-to 0.125, 8, 8,32, 32, 64 and le ss-than-or-equal-to 0.25 mug/ml for A pleuropneumoniae, 0.06, 1, less- than-or-equal-to 0.125, 8, 4, 64, 8, 32 and 8 mug/ml for P multocida, and 0.125, >64, less-than-or-equal-to 1, >64, 1, >64, >64, 64 and less -than-or-equal-to 0.25 mug/ml for S choleraesuis. These data confirm t he high in vitro potency of danofloxacin against field isolates that s how significant resistance to several other antibacterial drugs.