Cross-reactions between Salmonella typhi and 24 other bacterial species.

Cross-reactions between antigens from S. typhi and 24 other bacterial species were studied by quantitative immunoelectrophoretic methods. A sonicated S. typhi antigen preparation and a corresponding pooled rabbit antiserum regularly presenting 86 immunoprecipitates were used as a reference system. Antigens from Enterobacteriaceae cross-reacted intensively with the S. typhi antigens. No cross-reactions between S. typhi and antigens from gram-positive bacteria were found, and only a few cross-reactions with antigens from gram-negative bacteria outside the Enterobacteriaceae. The taxonomic perspectives of the immunoelectrophoretic approach are stressed by results showing that the number of cross-reacting antigens between S. typhi and other Enterobacteriaceae was positively correlated to the number of identical reactions in a collection of 28 biochemical tests.