Validation of the Snap St for Rapid Screening for Β-lactam Antibiotics in Milk

The SNAP was modified to SNAP ST (Idexx Laboratories Inc., Westbrook, ME), a new 7-8 minute test which no longer requires the use of an incubator. This new test was validated at ILVO-T&V according to Commission Decision 2002/657/EC and the CRL Guidelines for the Validation of Screening Methods (Anon., 2010). The SNAP ST is very specific as an interference was only caused by clavulanic acid, a βlactamase inhibitor. The repeatability of the reader and the test were very good. The SNAP ST detects all β-lactams with a MRL in milk at their respective MRL except for desacetylcephapirin and cefalexin. The test is robust for changes in the test protocol or differences in milk composition. Also goats’, ewes’ and mares’ milk could be screened by SNAP ST. The SNAP ST is a fast, simple and very reliable test for the screening of tanker milk on the presence of β-lactam residues. Introduction The SNAP β-Lactam ST is a competitive receptor test for the rapid detection of residues of β-lactams (penicillins and cefalosporins) in raw milk. The test is an improvement of the SNAP β-Lactam test, with an incubation at ambient temperature (15-30°C) so an incubator is no longer needed. The time to result for the assay is approximately 7 minutes (~45 seconds of milk flow time and 6 minutes of incubation at ambient temperature to allow for color development). A validation study was performed at ILVO-T&V according to Commission Decision 2002/657/EC and to the guidelines for the validation of screening methods for residues of veterinary medicines (Anon., 2010). Materials and methods