Evaluación de los períodos de resguardo de diferentes antibióticos de aplicación intramamaria en vacas con mastitis clínica

Abstract

The present study evaluated the withdrawal time in milk of eight different pharmaceutical formulas. Four of them contained only one antibiotic in its formulation (monodrugs). The remaining contained more than one drug (association). For each formulae, ten animals with clinic mastitis from different farms of Region Metropolitana were used. All formulas were administered according to the laboratories instructions.The Microbiological Analytical Cylinder Plate Method was used for laboratory analysis, using Bacillus subtilis BGA as the indicator organism. This method showed a sensibility of 0,08 µg/ml for cefoperazone and cefacetrile, and 0,04 µg/ml for pirlimycin.Time related concentrations were calculated in the monodrugs elaborating referente curves and the lineal regression equation was used to convert the inhibition halos, expressed in centimetres, in concentrations units µg/ml.Only qualitative results were obtained in the associations because the method does not detect antibiotics individually; these results were expressed as presente or abscence of antibiotics, according to the sensitivity levels of the method.The withdratwal times for cefoperazone were of 84 and 108 hours for group A and B respectively. For cefacetril and pirlimycin the withdrawal times were of 96 and 36 hours, respectively.The widhdrawal times for the association pharmaceutical formulas of lincomicin / neomicin /penicillin G sodic /dihidroestreptomicin / nafcillin and penicillin G procain / novobiocin / polimixin B / dihidroestreptomicin were of 72 hours. The espirimicin / neomicin association was of 96 hours.