Sorbitol-fermenting Escherichia coli O157, Scotland

To the Editor: Verotoxin-producing Escherichia coli (VTEC) of serogroup O157 causes severe gas-trointestinal and renal illness; clinical signs may be mild diarrhea, hemor-rhagic colitis, or hemolytic uremic syndrome (HUS). Typically, 10%– 15% of reported VTEC infections quickly progress to HUS (1). Sorb-itol-fermenting (SF)–O157 strains have emerged in continental Europe (2,3). Some evidence suggests that SF-O157 is more frequently associated with HUS than are non-sorbitol– fermenting strains (3–6). SF-O157 shows increased adherence to colonic epithelial cells and may in turn cause a more potent infl ammatory host response , resulting in a higher risk for HUS (4). The potentially greater virulence of SF-O157 requires urgent identifi cation of its reservoir(s) and vehicle(s) of infection, as well as determination of genetic or other pre-disposing factors for infection with this strain. To understand whether the host pathophysiologic responses to SF-O157 and non–SF-O157 strains differ, we analyzed a cohort of children with HUS who were infected with E. coli O157. During April and May 2006, Health Protection Scotland (HPS) identifi ed 18 cases of verotoxin-producing SF-O157 infection in Scot-land, 13 of which were associated with a nursery. HUS developed in 8 of the 18 patients; those with thrombotic microangiopathy were admitted to the renal unit of a specialist pediatric hospital , which immediately reports cases of HUS to HPS as part of national surveillance (7). To test the hypothesis that SF-O157 was more virulent than non–SF-O157, we performed an age-matched, nested case–case study of HUS case-patients and analyzed host clinical markers, treatment, and outcomes from SF-O157 and non– SF-O157 cases in 2006. Clinical questionnaires , patient information sheets, and consent forms were completed by clinicians for each case-patient and returned to HPS; data were entered into a database in Epi Info version 6 (Centers for Disease Control and Prevention , Atlanta, GA, USA). Statistical analysis by t test showed that nadirs for serum albumin were signifi cantly higher for children with SF-O157 HUS (p = 0.03; Table) than for children with non–SF-O157 HUS and that children with SF-O157 HUS had signifi cantly more sessions of hemodialysis than did children with non–SF-O157 HUS (p = 0.01; Table). All case-patients were oligoanuric; the 2 groups did not differ with respect to this parameter. Initial signs and symptoms were similar for both sets of patients , i.e., classic VTEC symptoms of bloody diarrhea and abdominal pain. This fi nding is in acccordance with those of other studies …