Detection of EspB using reversed passive latex agglutination: application to determination of enteropathogenic Escherichia coli.

We developed a new practical method to identify enteropathogenic Escherichia coli (EPEC) by detecting the pathogenic factor, EspB. E. coli were cultured in Dulbecco's Modification of Eagle's Medium (DMEM), and EspB was detected in the culture supernatant by reversed passive latex agglutination (RPLA). All 63 E. coli strains harboring the eaeA gene encoding intimin were positive for RPLA, and all 25 strains without the eaeA gene were negative. Among these 63 eaeA-positive strains, 38 Shiga toxin-producing E. coli (STEC) produced Shiga toxin (Stx) under the same culture conditions (DMEM). Subtypes of EspB alpha, beta and gamma were antigenically cross-reactive to each other as determined by RPLA and Western blotting. A kit for Stx detection (RPLA) is commercially available and therefore this RPLA for detection of EspB could be a practical method to define EPEC in both clinical laboratories and the field.