Screening methods for the detection of antibiotic residues in slaughter animals: comparison of the European Union Four-Plate Test, the Nouws Antibiotic Test and the Premi®Test (applied to muscle and kidney)

Microbial growth inhibition tests are widely used as the primary screening approach for the detection of antibiotic residues in slaughter animals. In this study we evaluated and compared the performance of the European Union Four-Plate Test (EU4pt), the Nouws Antibiotic Test (NAT), and a commercial ampoule test, the Premi®Test (applied to both muscle and kidney), by parallel analysis of 735 slaughter animals. The EU4pt only showed significant inhibition with two muscle samples containing 305 µg kg−1 doxycycline and 648 µg kg−1 tulathromycin, while an maximum residue limit (MRL) violation of 1100 µg kg−1 sulfamethazine remained unnoticed. Premi®Test-muscle only detected the sulfamethazine containing sample, all other (1.1%) suspect samples appeared false-positive results. The same test applied to kidney yielded 4.1% suspect samples, while the NAT screening (based on analysis of renal pelvis fluid) showed 4.9% suspect results. The vast majority of these samples contained tetracycline and/or aminoglycoside r...