A 2-year-old boy with hemolytic uremic syndrome and pneumocephalus

Clostridium septicum infection following hemolytic uremic syndrome is rare and carries a poor prognosis, especially when the brain is involved. We report a case of a previously healthy 2-year-old boy who presented with two days of anuria and bloody diarrhea. He was admitted to the local children's hospital with a diagnosis of hemolytic uremic syndrome, presumably secondary to E. coli O157. He soon required intubation and was noted to have fixed and dilated pupils. Head CT revealed left frontal subcortical white matter vasogenic edema and scattered pockets of pneumocephalus. The patient expired 14 hours after admission. Antemortem blood cultures grew C. septicum. Gross pathologic examination of the brain revealed a large intraparenchymal cerebral hemorrhage in the left frontal and parietal lobes. There was extensive cystic changes as well. Microscopic examination revealed vacuolization and diffuse colonization with rod-shaped bacteria, but without the expected tissue response. There have been only six previously reported cases of C. septicum infection following hemolytic uremic syndrome, four of which had brain involvement. Mortality rate is high, with the only known survivor among those with brain involvement having a brain abscess rather than diffuse pneumocephalus.