A note on inhibition test and electrophoretic detection limits of antibiotics used in British animal husbandry

A four plate microbiological inhibition test (the FPT) and a bioelectrophoretic method were evaluated for their ability to detect a range of antibiotic agents, which may be present as residues in animal tissues following their therapeutic use in animal husbandry. Both methods exhibited a wide range of sensitivities and several of the tested antibiotics could not be detected by either method. The pattern of responses across the bacterial plates in the FPT could not be used to identify agents and the bioelectrophoretic inhibition zone diameters were generally too large to allow the use of Rs values for identification. The Bacillus subtilis pH 7.2 plate with trimethoprim added was as effective as the four bacterial plates used in the FPT in antibiotic detection.