Microbiological inhibition-based method for screening and identifying of antibiotic residues in milk, chicken egg and honey

Abstract

This present study was designed to develop a novel microbiological inhibition-based method for the rapid screening and identification of antibiotic residues in milk, chicken egg and honey. Geobacillus stearothermophilus C953 was used as test bacterium in the detection system of this study. The optimization of nutrients and other supplements were performed to promote the growth of test bacterium and thus shorten the detection time. Furthermore, the synergetic agents were added to improve the sensitivity of test bacterium to more antibiotics. Additionally, confirmatory solutions such as β-lactamase, p-aminobenzoic acid, MgSO4 and cysteine were added to classify and identify different kinds of antibiotics. We observed that the LOD of this detection system was at or close to maximum residue limits established by EU for β-lactams, aminoglycosides, tetracyclines, sulfonamides, macrolides and quinolones in milk. The LOD of different kinds of antibiotics in chicken egg was less than or similar to the MRL and the LOD of Premi®test (except sulfonamides). For honey, there are no MRL, the LOD was less than or similar to the recommended concentration and the LOD of Premi®test. Noteworthy, the detection system also can identify these six kinds of antibiotics in milk, chicken egg and honey, and there were satisfactory results of specificity experiments and confirmation experiments by LC-MS/MS. Accordingly, the present study provides a reliable preliminary characterization of antibiotic residues in animal foods and improves the detection efficiency for the following chemical confirmation experiments by HPLC, LC-MS/MS, immunological and receptor-based tests.