Coagglutination and counter immunoelectrophoresis in the rapid diagnosis of typhoid fever.

The efficacy of two methods--coagglutination (COAG) and counter immunoelectrophoresis (CIE)--in the rapid diagnosis of typhoid fever was studied in parallel with blood and clot cultures on 114 clinically suspected cases. Retrospective analysis showed that only 58 eventually were discharged and had typhoid fever. Antigen detection on their sera was done by both methods, concomitant with antigen detection on culture supernates by CIE. Sera from 50 controls were subjected to both tests. Agglutinating anti-serum being unsatisfactory in the CIE system, anti-serum to the LPS fraction of Salmonella typhi "O" 901 was used in both tests after absorption with Escherichia coli and Salmonella paratyphi A. Analysis of data with reference to retrospectively confirmed typhoid cases show that S. typhi was isolated in 58.6% and 58.3% of blood and clot cultures; antigen detection by CIE in their supernates was 81.1% and 79.2%, respectively. This correlated closely with serum COAG (81.0%) in contrast to serum CIE (5.7%). Thus, COAG was superior to CIE for serology. However, CIE done on culture supernates precludes such tedious procedures as absorption of staphylococcal agglutinins and the confirmatory blocking test.