Shiga-Toxigenic Escherichia coli Detection in Stool Samples Screened for Viral Gastroenteritis in Alberta, Canada

• Published in: Journal of Clinical Microbiology
• Main Authors: Couturier, Marc Roger, Lee, Bonita, Zelyas, Nathan, Chui, Linda
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 2011
• Subjects: Northwest Territories; Nunavut; Yukon
• Online Access: http://dx.doi.org/10.1128/jcm.01693-10; https://journals.asm.org/doi/pdf/10.1128/JCM.01693-10

ABSTRACT Shiga-toxigenic Escherichia coli (STEC) is an important cause of diarrheal disease. The most notorious STEC serotype is O157:H7, which is associated with hemorrhagic colitis and hemolytic-uremic syndrome (HUS). As a result, this serotype is routinely screened for in clinical microbiology laboratories. With the bias toward the identification of the O157 serogroup in routine diagnostic processes, non-O157 STEC has been largely underrepresented in the epidemiology of STEC infections. This diagnostic bias is further complicated by the fact that many non-O157 STEC infections cause nonspecific gastroenteritis symptoms reminiscent of enteric viral infections. In this study, real-time PCR was used to amplify Shiga toxin genetic determinants ( stx 1 and stx 2 ) from enriched stool samples that were initially submitted for the testing of enteric viruses in patients with suspected viral gastroenteritis between May and September of 2006, 2007, and 2008 ( n = 2,702). Samples were submitted from the province of Alberta, Yukon, the Northwest Territories, and Nunavut, Canada. A total of 38 samples (1.4%) tested positive for Shiga toxin genes, and 15 isolates were cultured for further characterization. Several of the serotypes identified (O157:H7, O26:HNM, O26:H11, O103:H25, O121:H19, and O145:HNM) have been previously associated with outbreaks and HUS. This study outlines the importance of combining molecular methods with classical culture techniques to enhance the detection of emerging non-O157 as well as O157 serotypes in diarrheal stool samples. Furthermore, atypical diarrhea disease caused by non-O157 STEC can be routinely missed due to screening only for viral agents.