Serological diagnosis of salmonella infections by enzyme immunoassay.

An enzyme immunoassay (EIA) for the detection and measurement of serum IgM, IgG, and IgA antibodies to salmonella was developed with commercially available lipopolysaccharides (LPSs) of Salmonella typhimurium and S enteritidis combined as antigen. Of 130 sera from patients with culture-confirmed salmonella infections, 115 (88.5%) were positive in this assay. The classic Widal agglutination test was positive in only 50 (38.5%) cases. This EIA method offers a substantial advance in the serological diagnosis of acute salmonella infections; it detects antibodies to the salmonellae of groups B and D, which constitute about 70% of culture-positive cases of human salmonellosis. Antibodies to other salmonellae are also detected. This EIA is particularly valuable for the detection of salmonella antibodies during post-infectious complications when isolation of the organism is often no longer possible.