Selective Enrichment Broth and Chromogenic Agar for Detection of Enterohemorrhagic Escherichia coli O26, O103, O111, O121, O145 and O157

Abstract

Enrichment in modified EC broth (mEC) at 42ºC for detection of enterohemorrhagic Escherichia coli (EHEC) O26, O111 and O157 as an official method in Japan enhanced the growths of serogroups of O103, O121 and O145. In addition, various chromogenic agars were tested for the growth and morphology of various serogroups of EHEC. Multi or simple serogroups were distinguished in monocolor or various color depended in each serogroup. Furthermore, developed immunomagnetic beads targeting serogroups O103, O121 and O145 showed efficient performance to concentrate targeted bacteria in enrichment culture of food. In this study, it was suggested that enrichment in mEC, immunomagnetic separation method and culture on chromogenic agar were effective to isolate the 6 serogroups of EHEC.