The occurrence of antibiotic residues in 96 samples of pasteurized milk from six different brands found in commercial establishments in the city of Piracicaba, São Paulo, Brazil was investigated. Four different grades of milk were tested: two of type B, two of type C; one of type A; and one carton of UHT milk. The methodology used consisted of setting discs of filter paper saturated in milk over the surface of a TSB culture media previously inoculated with a test culture of Bacillus sthearothermophyllus. After an incubation of four hours at 56 ° C, halos of bacterial inhibition were observed, due to the presence of antibiotic residues. It was observed that 50.0% of the milk samples presented antibiotic residues, without a significant difference among them (p <=0.01). One of the brands presented 72.5% of the samples with penicillin residues and another presented 50.0% of the samples containing other inhibitors that were not identified by this methodology.
antibiotics in milk; penicillins; milk
