Enzyme immunoassay using peroxidase as a label and a dip-strip test for monitoring residual bacitracin in chicken plasma

A sensitive enzyme linked immunosorbent assay (ELISA) using horseradish peroxidase as a label enzyme and a simple dip-strip test using this ELISA which enable the monitoring of bacitracin (BC) in chicken plasma are described. The anti-BC antiserum which was raised against the antigenic BC-bovine gamma globulin conjugate in rabbit possessed an excellent specificity for BC, exhibiting no cross-reactivity with other antibiotics used as animal feed additives and veterinary drugs. The detection limit of BC by the ELISA was estimated to be 0.1 μg l−1 (equivalent to 1 ng of BC per 1 ml of chicken plasma). The recoveries of BC from chicken plasma ranged from 97% to 103%. The dip-strip using an anti-BC IgG dotted nitrocellulose membrane was prepared and a simple and rapid test for monitoring BC in chicken plasma was developed. Using this test, 50 ng of BC in 1 ml of plasma could be distinguished from that of control (blank) plasma.