Collaborative study of a microbiological screening method (three-plates) for the banned antimicrobial growth promotors tylosin, virginiamycin, spiramycin, zinc bacitracin and avoparcin in animal feed

Irene Pol-Hofstad (1)

1 Institute of Food Safety

Abstract A microbiological screening method (three-plate) for detection of the antimicrobial growth promoters tylosin, spiramycin, virginiamycin, zinc bacitracin and avoparcin in animal feed has been developed and validated successfully. A collaborative study involving 18 laboratories receiving 172 samples was carried out to verify the performance characteristics. The detection level for tylosin/virginiamycin/spiramycin, expressed in microbiological activity, was 1 mg kg -1 (false positives 2%, false negatives 3, 0, and 6% respectively). Avoparcin could be detected at 1 mg/kg in feed in general (false positives 2%, false negatives 0%). However, in calf feed, the sensitivity is lower. The percentage of false negatives was found to be 12%, 7%, 0% at 1, 3 and 5 mg kg-1 respectively (false positives 4%). Limit of detection for zinc bacitracin was 3 - 5 mg kg-1 (false positives 5-10%, false negatives 77% at 1 mg kg-1, 45% at 2 mg kg-1, 12% at 3 mg kg-1 and 4% at 5 mg kg-1. The method allowed for distinction between the groups of antibiotics: avoparcin/zinc bacitracin vs. tylosin/virginiamycin/spiramycin. This definitely gives an added value to the method in the frame of a follow up of positive screening results by post screening and confirmatory analysis. Key words: Microbiological screening method, validation, animal feed, antibiotics, collaborative study, spiramycin, virginiamycin, tylosin, zinc bacitracin, avoparcin

Mots clés: Life Sciences

Irene Pol-Hofstad. Collaborative study of a microbiological screening method (three-plates) for the banned antimicrobial growth promotors tylosin, virginiamycin, spiramycin, zinc bacitracin and avoparcin in animal feed. Food Additives and Contaminants, 2008, 25 (12), pp.1465-1474. ⟨10.1080/02652030802406201⟩. ⟨hal-00577323⟩