A Spatial Color Co-Recognition Immunochromatographic Assay Based on the Hue-Saturation-Brightness Color Space to Classify Salmonella Serogroups

Salmonella causes a huge proportion of foodborne diseases worldwide. There are over 2650 serotypes of Salmonella isolates with varying virulence and pathogenicity, while the serotype classification of Salmonella by traditional slide agglutination tests is time-consuming and tedious. Multiple immunochromatographic assays can distinguish multiple targets simultaneously in high throughput but are often limited to the visually confusing interpretation of the results. Herein, we established a spatial color co-recognition immunochromatographic assay based on the hue-saturation-brightness (HSB) color space to classify the 4 most common Salmonella serogroups (O:2, O:3, O:7, and O:9). The HSB color space was introduced to interpret the multicolor results of the strips. Thus, the four Salmonella serogroups could be classified clearly by one single test in the assay. The sensitivity and specificity of the spatial color co-recognition immunochromatographic assay for the four serogroups were both 100 %. An android app based on the HSB color space was also developed to interpret the test strip results. Compared to the common red-green-blue (RGB) color space, the HSB color space demonstrates better performance in the recognition of multicolor immunochromatographic strips. This study provides a novel and stable result interpretation assay for multicolor immunochromatographic assays and provides a fast and accurate classification method for Salmonella serogroups.