Pneumococcal Hemolytic Uremic Syndrome

Hemolytic uremic syndrome (HUS) consists of microangiopathic hemolytic anemia, acute renal failure, and thrombocytopenia. HUS typically follows a diarrheal episode, most frequently one caused by Shigella or enterohemorrhagic Escherichia coli. About 5% of cases are associated with Streptococcus pneumoniae (P-HUS); these atypical cases do not have a diarrheal prodrome. In a recent report, investigators retrospectively reviewed 43 P-HUS cases (34 proven, 9 suspected) that occurred from 1998 to 2005 at seven children’s hospitals in the U.K. These cases constituted 13.6% of the 316 HUS cases identified.

The 43 children all had known or suspected pneumococcal infections (pneumonia, meningitis, or bacteremia, alone or in combination). Among the 34 with confirmed P-HUS, pneumococci were identified by culture in 29 cases, by 16S rRNA sequencing in 3 cases, and by urinary pneumococcal antigen in 2 cases. The median age at presentation was 13 months. Of 12 isolates available for testing, 6 were serotype 19A, and only 2 were serotypes covered by the 7-valent pneumococcal conjugate vaccine. Thirty-six patients (84%) required dialysis (median, 10 days; range 2–240 days); six had plasma exchange. Five patients died, three from complications of meningitis, one from nosocomial sepsis with Pseudomonas, and one from a pulmonary embolus after 8 months. Data on follow-up (available for 35 of the 38 surviving patients; median duration, 9 months) showed that 10 children had significant renal dysfunction (1 dialysis-dependent). Only two of the children with meningitis had normal neurodevelopmental outcomes.