Decreased sialylation of IgA1 O‐glycans associated with pneumococcal hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) in children is usually caused by Shiga‐like toxin‐producing Escherichia coli, but approximately 5% of cases are caused by invasive pneumococcal infection (P‐HUS). Reported herein is the case of a 9‐month‐old HUS patient with pneumococcal meningitis who needed hemodialysis for 12 days. Decreased sialylation was characterized in both transferrin N‐glycans and IgA1 O‐glycans, analyzed in the acute phase on mass spectrometry, consistent with S. pneumonia‐produced sialidases hydrolyzing both α2,3‐ and α2,6‐linked sialic acids. The method will complement the T‐antigen activation test and help to understand the molecular pathology related to P‐HUS.