The Effects of Milk Components on the Minimum Inhibitory Concentrations of Bovine Mastitis Pathogens
Johnson, Tamea D.
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This experiment investigated the effects of milk components on the minimum inhibitory concentrations (MICs) of antimicrobial commonly used to treat bovine mastitis. The procedure for this experiment involved the use of and the alteration of agar dilution method recommended by the Nation Committee for Clinical Laboratory Standards. The alteration this method was done by the addition of various milk components to the test media. These components included milk cations, sodium caseinate, and sterilized milk. The MICs for several strains of S. aureus, S. uberis, and E. coli were determined for each media. The MIC values were found to be unaffected for penicillin, ampicillin, amoxacillin/clavulanic acid, cephapirin, and pirlimycin. The MIC values for ceftiofur, novobiocin, enrofloxacin, and streptomycin were all affected by the milk components. All of the MIC values of these antimicrobials increased where the various milk components were added. These results are indicative of lowered efficacy of those antimicrobials due to interactions with the milk components. The result of this experiment suggest that the current agar dilution method using a standard media may inaccurately predict in vivo results because the media does not accurately mimic the udder conditions.Missing pages 16-18.