DETECTION OF 4-QUINOLONE RESIDUES IN RAINBOW-TROUT (ONCORHYNCHUS-MYKISS WALBAUM) MUSCLE USING A BIOASSAY

The development of a bio-assay for the detection of 4-quinolone residu es in rainbow trout (Oncorhynchus mykiss Walbaum) muscle is described. The bio-assay depends upon a particularly sensitive isolate of Yersin ia ruckeri (Fish Diseases Laboratory, 39/81, Weymouth; National Collec tions of Industrial and Marine Bacteria, 13282, Aberdeen) allowing det ection of residues down to 0.02 mug/ml in muscle extracts. Traditional problems associated with bio-assays such as accuracy and precision we re examined and potential cross-reaction with other antibiotics licens ed for use in aquaculture which could affect the assay was also invest igated. Alongside existing physicochemical techniques the bio-assay po tentially provides an additional method both for quantifying residue l evels in pharmacokinetic studies and for carcass screening prior to hu man consumption.