The central Scotland Escherichia coli O157:H7 outbreak: risk factors for the hemolytic uremic syndrome and death among hospitalized patients

Abstract

Little is known about risk factors for complications of Escherichia coli O157:H7 infection in adults. The 1996 outbreak in central Scotland involved the largest number of adult case patients in whom hemolytic uremic syndrome (HUS) developed and, ultimately, the largest number of deaths associated with E. coli O157:H7 infection that has yet been recorded. We investigated risk factors for HUS in a retrospective study of all hospitalized case patients in this outbreak. Of 120 case patients, 34 had HUS develop, 28 of whom were adults. Sixteen adults died. Significant risk factors for HUS were age <15 years or >65 years (odds ratio [OR], 4.4; 95% confidence interval [CI], 1.3-14.4), hypochlorhydria (OR, 6.7; 95% CI, 1.9-24.0), and coincidental antibiotics (OR, 4.7; 95% CI 1.4-16.5). Factors associated with HUS were as follows: white blood cell count >20 x 10(9) cells/L (OR, 8.25; 95% CI, 1.1-60.3), neutrophil count >15 x 10(9) cells/L (OR, 8.5; 95% CI, 1.5-50.1), and serum albumin level <35 g/L (OR, 7.2; 95% CI, 1.2-42.5) < or =3 days after symptom onset. Deaths were confined to case patients >65 years of age. Early identification of risk factors for HUS is vital and could select case patients for trials of preventative and treatment therapies.