What Does STEC Stand For?
STEC stands for Shiga toxin-producing Escherichia coli, a group of pathogenic bacteria that produce Shiga toxins and cause significant gastrointestinal illness in humans. 1
Definition and Nomenclature
STEC refers to all E. coli strains that produce Shiga toxin, named for their structural and functional similarity to toxins produced by Shigella dysenteriae type 1. 1
These organisms are also known by alternative names including verocytotoxigenic E. coli and enterohemorrhagic E. coli (EHEC), though STEC is the preferred term in clinical guidelines. 1
The toxins come in two main types: Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2), with Stx2 being more virulent and strongly associated with hemolytic uremic syndrome (HUS). 1, 2
Clinical Significance
STEC causes approximately 100,000 illnesses, 3,000 hospitalizations, and 90 deaths annually in the United States. 1
The most notorious serotype is E. coli O157:H7, accounting for an estimated 73,000 cases yearly, though at least 150 non-O157 serotypes also cause human disease. 1
Approximately 8% of patients with O157 STEC infection develop HUS, a life-threatening complication characterized by thrombocytopenia, hemolytic anemia, and renal failure. 1, 3
Key Pathogenic Features
STEC are unique among diarrheagenic E. coli in producing Shiga toxins (types 1 and 2), which are the primary virulence factors responsible for bloody diarrhea and HUS. 4
These bacteria have an extremely low infectious dose (<100 organisms) for O157 and O111 serotypes, making them highly transmissible. 1
Cattle and other ruminants serve as the natural reservoir, with human infection occurring through consumption of contaminated food, water, or direct contact. 1, 4