AN EVALUATION OF THE IDEXX SNAP TEST FOR THE DETECTION OF BETA-LACTAMANTIBIOTICS IN EX-FARM RAW MILKS

The detection of antimicrobial residues in 1004 ex-farm raw milk sampl es by the IDEXX SNAP beta-lactam test and by the Delvotest P, as emplo yed in the Milk Quality Payment Scheme of the Milk Marketing Board for England and Wales, was compared. The repeatability of the SNAP test w as assessed by examining three penicillin G standards at each chosen l evel on each of the test occasions. One hundred samples giving positiv e results in the full MMB Quality Payment Scheme procedure were also e xamined by the SNAP test and the presence of beta-lactams was confirme d by a range of 'confirmatory' tests. In the routine survey of ex-farm milk samples, the SNAP test showed a > 98% correlation with the Delvo test P and the presence of beta-lactams in the majority of samples was demonstrated by the confirmatory tests. In the evaluation of 100 samp les previously identified as positive by the Delvotest P test, the SNA P test showed a greater-than-or-equal-to 95% correlation with the conf irmatory tests; only 2 of 98 positive samples could not be shown to co ntain penicillinase-sensitive beta-lactams. The SNAP test was able to detect beta-lactams within 10 minutes and provides a rapid, simple to use test that accurately detects penicillin G in bulked, ex-farm raw m ilks. The test could be employed, both by the farmer and the dairy to ensure that levels of beta-lactams in the milk supply remain below the Maximum Residue Limits currently defined in European Union legislatio n.