FURTHER-STUDIES ON THE FEASIBILITY OF ONE-DAY SALMONELLA DETECTION BYENZYME-LINKED-IMMUNOSORBENT-ASSAY

A model system previously developed for the rapid detection of Salmone lla typhimurium in foods was improved and extended to many other Salmo nella serotypes. The original protocol, which consisted of an overnigh t nonselective culture followed by a specific enzyme-linked immunosorb ent assay (ELISA), was modified and improved. A sandwich ELISA which u sed polyclonal antibodies for the capture stage and a cocktail of mono clonal antibodies for the detector stage was developed. The assay reco gnized a wide range of Salmonella serotypes; S. enteritidis, the most important serotype in the United Kingdom had a detection limit in the ELISA of about 4 x 10(2) cells ml-1. The cultural stage prior to the E LISA was either a single nonselective broth (incubated for 28 h) or a preenrichment broth (incubated for 7 h) plus a selective broth (incuba ted for 21 h). Antibodies which bind to cells grown in the unfavorable conditions of a selective medium were selected. It was concluded that , in the future, the shortened protocols for the detection of Salmonel la spp. in foods described here will be of considerable value.