Detection of antibodies to Salmonella "O" antigens in typhoid fever by counterimmunoelectrophoresis. I. Description of technique.

In the serum of patients with typhoid fever counterimmunoelectrophoretic techniques were used for the detection of antibodies to Salmonella "O" antigen. Lipopolysacharides (LPS) obtained with phenol and water from Salmonella typhi (antigens 0, 9 and 12) were used. Positive results were obtained in those patients with typhoid fever (20). The lower and higher titration levels were 1:8 and 1:32 respectively; the geometric mean was 1:16. The variation coefficient during the intra assay tests was 0.19, and remained stable throughout the inter-assay tests. Reproducibility, as well as a rapid technique, make this test a valuable tool for the serologic diagnosis of typhoid fever.