Abstract: A bacterial staining composition, process and apparatus for detection and quantitation of gram negative and gram positive bacteria in fluid samples are disclosed. The composition comprises a net negatively charged filter onto which bacteria are adsorbed and concentrated, an acid diluent which alters the electrostatic charge of the bacteria, thus enabling adsorption of the bacteria to the filter, a bacterial stain operative at about pH 8 to 12, and a washing reagent which enhances the diffusion of free dye away from the immobilized, stained bacterial. The color intensity at the center of the filter surface manifests the stained bacteria. It is compared to a standard color guide to determine the number of bacterial present in the fluid sample.

Abstract: An enzyme immunoassay based on membrane separation of antigen-antibody complexes wherein human or animal body fluid specimens containing an antigen are mixed with an enzyme-conjugated antibody specific for the antigen under test. Following incubation the antigen-antibody-conjugate mixture is passed through a filter membrane having an electrostatic charge providing an affinity for retaining antigen-antibody-conjugate complexes while not retaining free antibody-conjugate. Following washing of the filter membrane to remove free antibody-conjugate remaining thereon an enzyme substrate-chromogen reagent solution is applied to the filter membrane, which reacts with filter-bound antibody-conjugate and develops a visible or fluorogenic color indicative of the presence of antibody-conjugate.