Streptococcus Pneumoniae-Associated Hemolytic Uremic Syndrome Canadian Immunization Monitoring Program ACTive National Pediatric Surveillance (1991-2019)

Abstract Background: Streptococcus pneumoniae -associated hemolytic uremic syndrome (SP-HUS) is an underreported cause of pediatric non-diarrheal HUS. This study describes the epidemiology of the largest Canadian case series of SP-HUS in comparison with non-HUS invasive pneumococcal disease (IPD). Methods: The Canadian Immunization Monitoring Program, ACTive (IMPACT) is a national surveillance network for vaccine-preventable diseases. All confirmed IPD cases between 1991-2019 were included in the analysis. IPD cases with new HUS diagnoses were identified as SP-HUS cases, and the rest as non-HUS IPD cases. Results: There were 30 (0.4%) cases of SP-HUS amongst 6,757 IPD cases. The median age of SP-HUS cases was 27.5 months, with no significant differences between SP-HUS and non-HUS cases in age or sex. S. pneumoniae serotypes 3 (30%) and 19A (26.7%) were more common in SP-HUS compared to non-HUS cases ( P <0.0001). Pneumonia was more frequently observed in SP-HUS (67% vs. cases 26%; P <0.0001). All SP-HUS cases were hospitalized, compared with 71% non-HUS IPD cases (P=0.0004). SP-HUS cases had a longer median hospital length of stay (23.5 vs. 7 days; P <0.0001) and a higher proportion required ICU admission (70 vs 15.5%; P<0.0001). Moreover, ICU stays were longer in HUS cases compared with non-HUS cases (9 vs. 3 days; P <0.0001). All 30 SP-HUS patients survived while 3% of non-HUS cases died ( P= 0.33). Conclusion: SP-HUS was usually seen in IPD cases with pneumonia and was most commonly caused by serotypes 3 and 19A. Mortality was rare, but ICU care with lengthy hospital stay was common.