A screening method for beta-lactams in tissues hydrolyzed with penicillinase I and lactamase II

• Published in: Journal of AOAC International Vol. 81; no. 5; pp. 963 - 972
• Main Authors: Medina, M.B. (USDA, ARS, ERRC, Wyndmoor, PA.), Poole, D.J, Anderson, M.R
• Format: Journal Article
• Language: English
• Published: Gaithersburg, MD AOAC International 01-09-1998
• Subjects: ALIMENTOS; AMIDE HYDROLASE; AMIDE HYDROLASES; AMIDO HIDROLASA; ANALYTICAL METHODS; ANIMAL PRODUCTS; Anti-Bacterial Agents - metabolism; Anti-Bacterial Agents - pharmacokinetics; ANTIBIOTICOS; ANTIBIOTICS; ANTIBIOTIQUE; Bacteriological Techniques; BETA-LACTAM ANTIBIOTICS; BETA-LACTAMASE; beta-Lactamases - metabolism; beta-Lactams; Biological and medical sciences; CONTAMINACION; CONTAMINATION; DETECTION; Drug Residues - analysis; Drug Residues - pharmacokinetics; ENSAYO; Food Contamination; Food industries; FOOD SAFETY; FOODS; Fundamental and applied biological sciences. Psychology; HIDROLISIS; HYDROLYSE; HYDROLYSIS; INHIBICION; INHIBITION; INHIBITORY ACTIVITY; INNOCUITE DES PRODUITS ALIMENTAIRES; INOCUIDAD ALIMENTARIA; Meat and meat product industries; METHODE D'OPTIMISATION; METODOS DE OPTIMIZACION; OPTIMIZATION METHODS; Penicillinase - metabolism; PRODUCTOS DE ORIGEN ANIMAL; PRODUIT ALIMENTAIRE; PRODUIT ANIMAL; RAPID METHODS; RESIDU; RESIDUES; RESIDUOS; TECHNIQUE ANALYTIQUE; TECNICAS ANALITICAS; TESTAGE; TESTING; Tissue Distribution; Enzyme; Offals; β-Lactams; Meat product; β-Lactamase; Antimicrobial agent; Contamination; Microbiological method; Meat; Enzymatic method; Antibiotic; Analysis method; Quality control; Hydrolases; Detection; ELISA assay
• ISSN: 1060-3271; 1944-7922
• DOI: 10.1093/jaoac/81.5.963

Antibiotic residues above tolerance levels are not allowed in foods derived from farm animals. Microbial inhibition assays are used to screen antibiotics in U.S. regulatory laboratories. We developed a screening approach to classify beta-lactams through selective hydrolysis of the beta-lactam ring with Penase or lactamase II, thereby inactivating the beta-lactam activity. Optimum conditions for hydrolysis of beta-lactams with Penase and lactamase II were determined. beta-Lactams were detected by a microbial inhibition assay and with enzyme-linked immunosorbent assays before and after hydrolysis. beta-Lactams (10-100 ppb) were spiked in kidney extracts and hydrolyzed. Results indicate a pattern that tentatively classified the beta-lactams into 3 subgroups. Desfuroyl-ceftiofur-cysteine, a major metabolite of ceftiofur, was clearly detected. Penicillin G, ampicillin, amoxicillin, and cloxacillin were distinguishable from cephapirin, ceftiofur metabolite, and high levels of hetacillin. Liver and kidney tissue samples were analyzed with the combined enzyme hydrolysis and screening assays, which tentatively identified the residues. This approach can speed up screening analysis of beta-lactam residues prior to identification and quantitation by chromatographic analysis, thus enhancing positive identification of residues to provide a safer food supply