[Comparison of the ELISA (lipopolysaccharide) and Widal reactions (O antigen) in the diagnosis of Salmonella infections].

At various times after the onset of disease 50 sera of patients with bacteriologically proven salmonella infections were investigated for O-antigen specific antibodies in ELISA and Widal-tests. 21 of these sera were derived from patients with typhoid fever, 10 from patients with gastroenteritis due to various species of salmonella group D and 19 from patients with group B salmonella-gastroenteritis. Additional 44 sera stemming from patients without such infection were included in the investigation as a control. With ELISA the sera were examined for antibodies of the IgM- and IgG-class separately. As antigens lipopolysaccharide W-preparations from S. typhi ("group D-antigen") and S. typhimurium ("group B-antigen") were used in the ELISA. High reciprocal titers (geometric means: 1404, 2560, and 1020) of IgM were demonstrable in sera drawn 11-30 days after onset of the disease with group D- and group B-antigen respectively (Fig. 1, Table 1 and Table 2). With increasing distance of time from the onset of the disease these titers decreased rapidly. The titers of agglutinating antibodies as measured in the Widal-test behaved similarly to those of IgM (Fig. 1, Table 1 and 2), and the correlation between both was high (r = +0.93, Fig. 2). In contrast, titers of IgG-antibodies reached their maximum later, namely 31-60 days after onset of the disease (Table 1), and the correlation to the agglutinin-titers (r = +0.33, Fig. 3) was much lower. In sera of patients with typhoid fever reciprocal titers of IgM against the homogeneous group antigen surmounted those of IgG at the average by about 5 log2-step (mean g: 1404 and 79 respectively) between the 11th and 30th day of disease. At this stage of the disease also sera from patients with gastroenteritis due to both salmonella D or B demonstrated clearly an IgM-dominated ratio. After a period of more than 2 month this ratio was about 1:1 in sera of patients with typhoid fever or with salmonella group D-gastroenteritis, but was clearly IgG-dominated in sera obtained from patients with group B-gastroenteritis. This might be due to the fact that most of the sera classified as "obtained greater than 2 months after onset" stemmed from excreters of salmonella B species.(ABSTRACT TRUNCATED AT 400 WORDS)