Development of a rapid immunochromatographic test to identify enteropathogenic and enterohemorrhagic Escherichia coli by detecting EspB

A rapid immunochromatographic (IC) test to identify enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC, respectively) was developed to detect EspB secreted by the type III secretion system of these bacteria. The detection limit of the test system was 4 ng/mL. All 33 of 34 strains harboring the eae gene encoding intimin were positive in the IC test, and all 40 of the eae-negative strains were negative. The results showed that the sensitivity was 96.9% and specificity was 100%. The IC test also detected EspB in a stool sample artificially supplemented with 60 ng EspB/mL. The IC test for the detection of EspB may be a practical method to define EPEC or EHEC both in clinical laboratories and the field.