Enterohemorrhagic E. coli (EHEC) are strains capable of producing Shiga toxin and typically cause bloody diarrhea [1-3]. Hemolytic-uremic syndrome (HUS) complicates 6 to 9 percent of EHEC infections overall, and about 15 percent of EHEC infections in children under age 10 [3-5]. Since the initial recognition of severe bloody diarrhea due to E. coli O157:H7 in the United States in 1982, outbreaks and sporadic infections have been attributed to EHEC worldwide [4-21]. In May 2011, a new Shiga toxin-producing EHEC strain, O104:H4, was identified as the cause of an outbreak in Germany and other countries in Europe [22,23].
The clinical manifestations, diagnosis, and treatment of EHEC will be reviewed here. The microbiology, pathogenesis, epidemiology, and prevention of EHEC infections are discussed separately. (See "Microbiology, pathogenesis, epidemiology, and prevention of enterohemorrhagic Escherichia coli (EHEC)".)
The incubation period between exposure to Enterohemorrhagic E. coli (EHEC) and the onset of symptoms is typically three to four days (range one to nine days) . Clinical manifestations may include history of bloody diarrhea, a visibly bloody stool specimen, no reported fever, a peripheral white blood cell count above 10,000/microL, and abdominal tenderness [3,10,24]. In one large series, three or more of these features were present in 65 percent of patients with E. coli O157:H7 infection (compared with 19 percent of those with infection due to Shigella, Campylobacter, or Salmonella) .
Hemolytic-uremic syndrome is a major complication of EHEC infection, discussed below. (See 'Hemolytic-uremic syndrome' below.)
Hospitalization is required in 23 to 47 percent of symptomatic patients with acute diarrhea due to EHEC, with a median hospital stay of 6 to 14 days [4,6,7]. The mortality rate is generally 1 to 2 percent, although it may be substantially higher among the elderly and among patients with HUS [4,25]. Uncomplicated EHEC infection generally resolves in approximately one week.