IMMUNE-RESPONSE TO ESCHERICHIA-COLI O157-H7 IN HEMOLYTIC-UREMIC SYNDROME FOLLOWING SALMONELLOSIS

Escherichia coli O157:H7, a Shiga-like toxin (SLT)-producing enteric p athogen, has been implicated in most cases of post-diarrheal hemolytic uremic syndrome (D+HUS). Infection with other bacterial pathogens suc h as Salmonella has also preceded D+HUS episodes, leading to speculati on that these organisms may also be etiological. We present two childr en with unrelated D+HUS following salmonellosis. Both children had neg ative stool cultures on sorbitol-MacConkey agar soon after the onset o f diarrhea. After the diagnosis of HUS, both patients had repeat stool cultures positive for Salmonella alone. Polymerase chain reactions fo r SLT I and II gene sequences in Salmonella isolates were negative. En zyme-linked imunosorbent assay for specific humoral response to E. col i O157:H7 lipopolysaccharide in acute and convalescent serum samples r evealed evidence of heretofore undetected E, coli O157:H7 infection co ntemporaneous with each D+HUS episode. These cases demonstrate that is olation of only non-SLT-producing microbes from children with D+HUS sh ould raise suspicion of concurrent undetected infection with SLT-produ cing organisms. Assaying specific immune response to E. coli O157:H7 c an be an important epidemiological adjunct. Bacterial infection with n on-SLT-producing Salmonella may represent concomitant enteric patholog y rather than D+HUS-instigating infection.