Authors: Vivian M. Lockary, Amanda J. Bruesch, and Christopher L. Ball

Affiliation: Idaho Bureau of Laboratories

Title: Combined Use of Culture and Non-Culture Toxin Based Screening Methods Demonstrate Increased Diversity and Prevalence of Shiga Toxin Producing Esherichia coli in Southern Idaho

Abstract: Shiga toxin producing Escherichia coli (STEC) O157:H7 has gained international notoriety as the primary etiologic agent of hemorrhagic diarrhea and hemolytic uremic syndrome (HUS) following consumption of contaminated water or food products.  Although O157:H7 STEC is the most commonly encountered serotype, its importance is exaggerated due to over reliance on culture based methods in diagnosis.  There are more than 50 other STEC serotypes that have been associated with diarrheal illness when both culture and non-culture toxin based detection methods are used.  In Idaho, for example, STEC O26:H11, O111:NM, and O121:H19 have all been recovered in significant proportions.  Since 2002, the Idaho Bureau of Laboratories has collaborated with three regional medical centers in Southeastern, South Central, and Southwestern Idaho to implement combined culture and toxin detection methods in routine stool culture protocols.  In all three regions, this testing algorithm has shown that at least 50% of the recovered, non-outbreak associated, clinical isolates were non-O157 STEC serotypes.  This data clearly illustrates the need for the combined use of culture and toxin based testing to assess the burden of STEC disease in Idaho.