Short communication: Detection limits of non-beta-lactam antibiotics in goat's milk by microbiological residues screening tests

This study compares the performance of 4 antimicrobial residue screening tests [brilliant black reduction test AiM (Analytik in Milch Produktions- und Vertriebs GmbH, München, Germany), Delvotest MCS (DSM Food Specialties, Delft, the Netherlands), Eclipse 100 test (ZEU-Inmunotec SL, Zaragoza, Spain), and Copan Milk Test (Copan Italia S.p.a., Brescia, Italy)] used to detect 20 antimicrobial agents (aminoglycosides, macrolides, tetracyclines, sulfonamides, and quinolones) in goat's milk, according to International Dairy Federation guidelines. Composite milk samples from 30 antibiotic-free goats were used to prepare spiked milk samples and 11,520 analytical determinations were carried out. According to a logistic regression model, agreement coefficients were greater than 98% for most of the antibiotics, with higher b values obtained for macrolides. Neither tetracyclines nor quinolones were detected at European Union maximum residue limits. Only the Copan Milk Test and the Delvotest MCS were able to detect 3 antimicrobials below their maximum residue limits (neomycin, tylosin, and sulfadimethoxine). Given that these tests are used in control programs for goat's milk, our results indicate their sensitivity would need to be improved to guarantee safety for consumers.