Resolution of Escherichia coli O157 : H7 that contaminated radish sprouts in two outbreaks by two-dimensional gel electrophoresis

Two-dimensional get electrophoresis (2-DE) was performed to examine exoprot eins and periplasmic proteins of Shiga toxin-producing Escherichia coli (ST EC) 0157:H7 strains isolated from cases associated with radish sprouts in t wo outbreaks. We found that STEC 0157:H7 released a large number of protein s into the medium during the stationary phase of growth, as observed with 2 -DE. Although pulsed-field gel electrophoresis (PFGE) patterns of STECs NGY 9 (RIMD0509894), a Sakai isolate; NGY33, a Gamagoori isolate; and NGY120, a Kanagawa isolate, were all the same, comparison of 2-DE patterns of exopro teins and periplasmic proteins clarified that NGY9 was distinct from NGY33, whereas NGY33 and NGY120 were of close lineage. We therefore suggest that 2-DE analysis of exoproteins and periplasmic proteins is a powerful epidemi ological method with high resolution.