The patient is infected with E. coli 0157:H7. In general, antibiotic therapy has not been shown to be helpful in such cases. Antibiotic therapy does not appear to shorten the clinical course of the infection and also does not appear to reduce the incidence of hemolytic uremic syndrome, which can develop in patients with this particular infection. Thus, treatment of E. coli 0157:H7 infection is largely supportive.