[Identification of enteropathogenic strains of E. coli (EPEC) by application of the latex test. I. Evaluation of specificity and sensitivity of the test].

The study was aimed at elaboration of the test and evaluation of specificity and sensitiveness of it during routine diagnosis and detection of enteropathogenic strains of E. coli (EPEC), basing on direct identification of O antigen of these bacteria. The studies was performed by application of polystyrene latex having particles of 0.8 micron in diameter and coated with rabbit globulins immune for O antigens of 14 serotypes of E. coli identified in Poland as EPEC strains. Fourteen univalent reagents and three multivalent reagents (identifying 4-6 group antigens) were used. Latex reagents, prepared by own method, reacted only with suspensions of homologous strains of E. coli, not agglutinating in presence of O antigens of remaining EPEC strains. Evaluating specificity of univalent reagents against suspensions of bacteria representing 111 other than EPEC strains of E. coli, it was found that only in 5 cases agglutination did occur in presence of heterologous cell suspensions. These reactions concerned strains representing 03, 04, 010, 090 and 0106 group antigens. Comparative studies performed with latex and slide agglutination tests and OK sera on 391 freshly isolated samples of feces of children (determined in regional laboratories as EPEC) have shown that as a results of serological reidentification of these strains with commercial OK sera for 14 serotypes of EPEC, positive result of agglutination test was obtained only with 277 (70.8%) of strains. These results suggest a possibility of application of latex reagents for detection of EPEC strains basing on identification of O antigen of these bacteria.