The United States National Prospective Hemolytic Uremic Syndrome Study
The United States National Prospective Hemolytic Uremic Syndrome Study: microbiologic, serologic, clinical, and epidemiologic findings. Banatvala N, Griffin PM, Greene KD, Barrett TJ, Bibb WF, Green JH, Wells JG; Hemolytic Uremic Syndrome Study Collaborators. Journal of Infectious Diseases 2001;183(7):1063-1070.
Hemolytic uremic syndrome (HUS) typically develops after a prodromal diarrheal illness but may occur without diarrhea and is the major cause of acute renal failure in children. Shiga toxin producing Escherichia coli (STEC) and Shigella dysenteriae type 1 both have been clearly associated with HUS. Current evidence suggests that STEC cause all or almost all cases of postdiarrheal HUS in developed countries, and several studies have suggested that E. coli O157:H7 is the major cause of postdiarrheal HUS in North America. Some adults diagnosed with thrombotic thrombocytopenic purpura (TTP), a syndrome characterized by symptoms similar to those of HUS but with the addition of fever and neurologic symptoms, also have STEC infection. Unlike most persons with TTP, those with TTP-associated STEC infection generally have preceding diarrhea. The proportion of HUS patients infected with E. coli O157:H7 or other STEC serotypes can be difficult to determine, because HUS is usually diagnosed several days after the onset of diarrhea, a time when the number of pathogens in the stool is decreasing. This delay in diagnosis and the antimicrobial treatment before stool specimens are obtained in some patients decrease the yield from stool cultures. Serology provides an alternative method of diagnosis. To date, the value of serologic diagnosis of E. coli O157 infection in HUS has not been fully assessed, and temporal changes in the E. coli O157 isotype specific antibody response have not been described. This paper describes the frequency of different STEC serotypes in a cohort of children and adults enrolled in a nationwide prospective study of postdiarrheal HUS from 1987 through 1991. It also identifies the proportion of patients with IgM and IgG lipopolysaccharide (LPS) antibodies to E. coli O157 and documents the variation in antibody response over time. The clinical and epidemiologic features are also described. Among 83 patients, STEC were isolated from 30 (43%) of 70 whose stool cultures yielded bacterial growth (25 E. coli O157 isolates and 5 non-O157 STEC isolates). Fifty-three (80%) of 66 patients with serum samples had positive O157 LPS antibody titers. Of the 83 patients, 60 (72%) had evidence of STEC infection, including six of eight adults whose illnesses also met criteria for TTP. Data from a subset of patients suggest that E. coli O157 was the cause of 80% or more of the STEC infections. All three women who were postpartum had evidence of E. coli O157 infection. The median interval between the onset of diarrhea and HUS diagnosis was five days. Visible blood was present in the stool in the 21 days before HUS diagnosis in 73%; 78% had abdominal pain, and 22% had upper respiratory tract infection symptoms. One-fourth of the patients had major neurologic complications, 22% had seizures, 5% encephalopathy, and 1% had aphasia. Red cell transfusions were done in 37% of patients and 55% required dialysis. Of the 73 children, 11% had illnesses consistent with TTP and 6% died, although none of the children who died had illness that met the criteria for TTP. Of the 10 adults, 80% had TTP and two of those patients died. This suggests that the pathophysiologic characteristics of STEC-associated HUS in adults is different from that in children. By monitoring trends in the incidence of HUS over time, active surveillance, which began in 1997 in the U.S., will provide critical information for evaluating the impact of measures to decrease environmental contamination. By monitoring trends in the proportion of HUS cases due to different STEC serotypes, this system will alert the public health community to emerging serotypes.