Patent Evaluation: Assay Method for Detecting the Presence of Bacteria

Summary

Novelty: A method is described for detection and quantitative of pathogenic bacteria. The method involves the antibody capture of the target bacteria, the production of colonies, transfer to a membrane and detection with labelled antibodies. The method is suitable for the detection of low levels of pathogenic organisms in serum samples, tissue samples and food samples, with a high level of discrimination.

Biology: The bacterial assay system involves the binding of a specific antibody to an insoluble matrix (such as magnetic beads) via protein A. The use of protein A increases the effectiveness of capture by the antibodies. On contact between the sample and the matrix, specific bacteria are immobilized. The immobilized cells are placed on a suitable medium and cultured to produce colonies. Cells from colonies are transferred to a membrane (nylon, etc.) by replica plating and fixed by chemical treatment. Detection of the specific bacteria involves the use of a specific monoclonal antibody which is subsequently detected by use of a second, enzyme-linked antibody. The use of this method in the detection of Salmonella, E. coli and Listeria is reported.