Bacteria as solid phase in a concentration fluorescence immunoassay analysis of antibodies to surface antigens.

A modified solid-phase fluorescence immunoassay was developed using bacterial cells as the solid phase to screen antibodies produced against surface antigens from a clinical isolate of Escherichia coli, strain 1-149. The bacterial solid phase was used to analyze both polyclonal and monoclonal antibodies. The bacterial concentration fluorescence immunoassay (BCFIA) showed up to 50-fold greater sensitivity in bacterial cell detection as compared to ELISA (enzyme-linked immunosorbent assay). Moreover, BCFIA was considerably faster than ELISA with uniform reproducibility. This paper demonstrates the utility of using bacteria and their surface antigens as solid-phase matrices for antibody characterization in a FIA.