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The BioStar® OIA® SHIGATOX assay is an Optical Immunoassay (OIA) test for the qualitative, rapid detection of the presence of Shiga Toxins in human diarrheal fecal specimens, broth cultures, and swab sampling of colonies from a culture plate. This test is intended for in vitro diagnostic use as an aid in the diagnosis of infection by Shiga Toxinproducing Escherichia coli (STEC), both 0157 and all non -- 0157 Shiga toxin producing strains.

The BioStar OIA SHIGATOX device is based on a novel thin film optical detection technology that relies on the interaction of white light with thin films to create a destructive interference phenomenon. Characteristic of this phenomenon is the generation of a reflective surface that changes color as a function of the change in optical thickness (refractive index x thickness) of the films on the surface of the device. To take advantage of this phenomenon for monitoring biological binding events, the optical surface with a special background color is coated with a capture reagent specific to the analyte of interest. In the OIA SHIGATOX device, the biological capture film is a combination of affinity-purified polyclonal antibodies to Shiga toxins 1 and 2 (Stx 1 and Stx 2). Samples suspected of containing either or both of the toxins are mixed with cocktail containing polyclonal antibodies to Stx 1 and Stx 2 that have been covalently conjugated to horseradish peroxidase (HRP). Once a sample containing toxins or either toxin is applied to the surface, the immune complex of toxin(s) and the anti-toxin-HRP conjugate(s) are bound to the surface antibodies. Following a wash step, a precipitating substrate for HRP is added, and a thin film generated by the immobilized immune complex is enhanced by the precipitation of the HRP product. Once washed and dried, a simple color change relative to the gold background color is observed as an indication of the presence of Stx 1 or Stx 2 in the original specimen. The OIA SHIGATOX device produces a qualitative result for the presence or absence of Shiga toxin as the device output. Input to the device is the simple addition of an aliquot of fecal material or broth culture to the reagents contained in the kit. Fecal samples are routinely collected, and no special collection requirements exist beyond the elimination of the use of fecal transport media. Test devices within the kit are single use devices, and disposal instructions are provided in the Package Insert. The kit contains all components necessary for analysis of the direct stool sample with the exception of a timer.