Multiple outcomes of patients with acute bloody diarrhea and suspected STEC infection

This figure portrays the sequence of events following presentation and the impact of clinical course and microbiologic testing on clinical management. Circles with dashed outlines reflect uncertain risk, circles with thin outlines represent low or no risk, and the circle with a thick outline signifies high-risk situations. Most commonly, patients infected with high-risk STEC present with bloody diarrhea (left panel). However, microbiology laboratories use the same techniques to seek bacterial enteric pathogens on all submitted stools. When an STEC is detected but the toxin genotype is not specified (the situation described in the circle with the dashed border, right panel), the likelihood that a Shiga toxin 2-producing E. coli is increased if the diarrhea is bloody. In regions where E. coli O157:H7 is the most common high-risk STEC, the likelihood of a high-risk STEC infection is increased whether or not the diarrhea is bloody. Refer to other content in this section for details on the management of suspected or documented high-risk STEC.