Use of a rapid latex agglutination test to detect Salmonella and Shigella antigens from gram-negative enrichment broth.

The Wampole Bactigen Salmonella-Shigella is a latex agglutination test for rapid detection of Salmonella and Shigella from enteric enrichment broths. It is designed to identify those enrichment broths that require subculturing and eliminate further workup of negative broths. The authors compared the results of latex testing of gram-negative enrichment broths with culture results of the same broths. Primary culture plates were also inoculated with each specimen. A total of 2,481 rectal and stool specimens were used in the study. All specimens were inoculated onto a selection of primary culture media, and the specimen was placed into gram-negative broth. After incubation, the broths were tested with the latex and then subcultured to enteric agars. A total of 99 Salmonella and 29 Shigella were cultured from the specimens, with the latex test detecting 85 of 99 (85.5%) of the Salmonella and 26 of 29 (89.6%) of the Shigella. The overall specificity of the test was 96.4%, and the percentage agreement between latex and culture results was 95.9%.