Detection of antibiotic residues in consumer milk supplies in North America using the Charm Test II procedure

Two hundred and fourteen consumer milk samples from across North America were examined for antibiotics residues by means of the Bacillus stearothermophilus disc assay (Charm test) and the competitive isotopic (Charm Test II) procedure. Of the 174 samples taken from 16 states, 150 results were positive for one or more antibiotics. The greatest number of positives were sulphamethazine, 82, and tetracyline, 48. Candian samples, 40, also showed the same problem related to tetracycline, 12, and sulphamethazine residues, 12. The Bacillus stearothermophilus disc assay procedure was unable in most cases to detect these residues possibly due to the lower sensitivity of this test. Further comparative tests between Charm Test II and other methods of similar sensitivity are recommended to confirm these findings.