Pneumococcus-induced T-antigen activation in hemolytic uremic syndrome and anemia.

The hemolytic uremic syndrome (HUS) is most commonly associated with Escherichia coli, but has been associated with other infections such as Streptococcus pneumoniae. Pneumococcus-induced HUS carries an increased risk of mortality and renal morbidity compared with E. coli-induced HUS. The pneumococcal organism produces an enzyme, which can expose an antigen (T-antigen) present on erythrocytes, platelets, and glomeruli. Antibodies to the T-antigen, normally found in human serum, bind the exposed T-antigen, and the resultant antigen-antibody reaction (T-activation) can lead to HUS and anemia. Clinicians need to be aware to request specific testing when pneumococcus-induced HUS/anemia is suspected, as current blood banking techniques do not routinely test for the presence of the T-antigen. Once this association is documented, washing all blood products and avoiding plasma products, if possible, is recommended. Plasmapheresis can be considered for the more critically ill patient. The incidence of pneumococcus-induced HUS may be increasing. We report six cases of pneumococcus-induced HUS/anemia presenting at our hospital.