Update on Shiga toxin-producing E coli infections

Escherichia coli O157:H7 (the "burger bug" or one serotype of the Shiga toxin-producing E coli [STEC]) was first identified as a human pathogen 20 years ago. Today, along with certain non-O157:H7 strains, E coli O157:H7 causes significant endemic illness among children and adults in the United States. STEC may result in bloody diarrhea and may be accompanied by complications, including hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura. This article reviews the modes of STEC transmission, the spectrum of disease and its clinical presentation, and risk factors for developing HUS. Methods of detecting STEC and the limitations of these methods in the immunocompetent host also will be discussed. The debate about treating STEC infections with antibiotics will be addressed, within the broader context of the Infectious Diseases Society of America guidelines for managing infectious diarrhea. Patients with STEC infections should be monitored carefully for signs of HUS, particularly individuals with risk factors for this complication. Primary management is hydration while avoiding antibiotics and antimotility agents. Therapy for bloody diarrhea varies depending on the etiology. The primary care physician should evaluate all bloody diarrheas for a potential infectious etiology, including STEC, before conducting additional evaluations to diagnose possible noninfectious etiologies for gastrointestinal bleeding.