Minimum inhibitory concentrations of some antimicrobial drugs against bacteria causing uterine infections in cattle
- I. M. Sheldon, BVSc, PhD, DCHP, DBR, DipECAR, MRCVS1,
- M. Bushnell2,
- J. Montgomery, BSc1 and
- A. N. Rycroft, BSc, PhD2
The minimum inhibitory concentrations (MICs) of oxytetracycline, cephapirin, cephapirin/mecillinam, cefquinome, ceftiofur and enrofloxacin, candidate antibiotics for the principal bacteria associated with uterine infections: Escherichia coli, Arcanobacterium pyogenes and the anaerobic bacteria Fusobacterium necrophorum and Prevotella melaninogenicus, were determined by the agar dilution method. The bacteria were isolated from animals with clinical metritis and/or endometritis. For E coli, cefquinome and enrofloxacin had the lowest MIC90 and MIC50 values (<0.06 μg/ml), and oxytetracycline and cephapirin had the highest values. For A pyogenes, oxytetracycline had the highest MIC50 value (16 μg/ml), but all the cephalosporins had values below 0.06 μg/ml. For the anaerobic bacteria, enrofloxacin and oxytetracycline had the highest MIC50 values but all the cephalosporins had values of 0.06 μg/ml or below.
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