ENTEROHEMORRHAGIC E-COLI (EHEC), THE MOST IMPORTANT CAUSE OF HEMOLYTIC-UREMIC SYNDROME IN CHILDREN - EVALUATION OF DIFFERENT TECHNIQUES OF EHEC INFECTION

Enterohemorrhagic Escherichia coli (EHEC), have been associated with p athogenesis of hemolytic uremic syndrome (HUS) worldwide. Our aim was to determine the association of EHEC infection and HUS in Chilean chil dren. During may 1991 and october 1993, 34 children with HUS and 33 ag e matched controls (children with diarrhea that did not develop HUS) w ere enrolled in a case/control study. For each child a stool and serum sample were obtained at admission. Stools were processed for common e nteropathogens and for EHEC identification. EHEC were identified in st ools by gene probes for different virulence factors (EHEC plasmid-asso ciated fimbria, Shiga-like toxin I, Shiga-like toxin II and eae adhere nce factor) and by detection of free fecal toxin by a neutralization a ssay in Vero cells. Sera were processed for anti-cytotoxin antibodies also by an assay in Vero cells. Enteropathogens were isolated in 20.6% and 15.5% of HUS and control children respectively (p=NS). 91% of the HUS children and 73% of the control children were EHEC positive by, o ne or more of the techniques used (p = 0.05). Of the three detection m ethods used for EHEC, only free fecal cytotoxin was significantly more common in HUS children than controls (45.5% us 9% p = 0.007). Genotyp e patterns of HUS and controls strains were similar except for a trend towards a higher frequency of non-toxigenic non-toxigenic strains in the control group. Serogroup 0157 was more common in HUS children than in controls (9% vs 0% p = 0.036). In Chile as in other countries EUEC infection is common and significantly associated with occurrence of H US. Infection with EHEC strain 0157 seems to be an important risk fact or for HUS.