A modified method for the detection of antibiotic residues in slaughter animals.

Biological methods in current use for the detection of antibiotic residues in slaughter animals are reviewed. A modified method is suggested in which the conditions for the control have been standardized. By the use of a semi-defined medium, the batch-to-batch variations are minimized. In order to facilitate the detection of sulfonamides the medium is supplemented with trimethoprim. The standardized conditions included the use of a sporulating organism, Bacillus subtilis, an inoculum size of 0.5 × 10⁵ spores per ml medium, and 5 ml medium of pH 6.0 per plate. A preincubation-diffusion time of 1 h in room temperature is recommended before incubation.The modified method was compared with the currently prescribed Swedish method. The new method was easier to perform and showed a more uniform sensitivity to most of the antibiotics used.