Sr. Director:
Recently it has published in Nefrologia a case of haemolytic uremic syndrome associated to pneumococcal infection (SP-HUS) in a 2-year-6-month old boy with pneumonia, that required venovenous hemodiafiltration/hemofiltration during ten days. SPHUS is an uncommon disease whose incidence, following invasive pneumococcal infection, is estimated at 0.4-0.6 %.
Its mortality rate is high, also in recent series, when compared with cases secondary to Shiga-like toxic-producing E. Coli infection (STEC-HUS). Exposition of Thomsen¿Friedenreich cryptantigen (TF) present on the surface of erythrocytes, platelets and glomerular endothelial cells, by pneumococcal neuraminidase seems to trigger clinical manifestations.
Early recognition allows a proper treatment. Avoidance of plasma infusion and transfusions of unwashed blood products affects morbidity and mortality, as IgMcontaining blood derivatives may increase cellular damage.
We present a case of a 18-month old girl with high fever (40 °C) and cough for five days; she was admitted for right pneumonia with pleural effusion. She was anaemic (Hb 5.6 g/dL) with marked anisocytosis and schistocytosis and thrombocytopenic (30 ´ 109 /L).
Fibrinogen levels, and prothrombin and partial thromboplastin times were normal, while a direct Coombs¿ test was positive. Creatinine was mildly increased (61 Ìmol/L ) in presence of microhematuria and proteinuria. A rapid assay for detection of Streptococcus pneumoniae urinary antigen was positive. Subsequently Streptococcus Pneumoniae resulted from an hemoculture.
Intravenous antibiotic therapy (ceftazidime + vancomycin) was administered. The patient was transferred into a paediatric nephrology department. Six days after admission a drainage of the persisting pleural effusion was performed. Four transfusions of washed irradiated red blood cells were necessary to correct the severe anaemia.
Creatinine peaked at 79 Ìmol/L, to return quickly toward normal values; diuresis and blood pressure were always normal. No dialytic treatment was required. One month after admission the patient was good with complete recovery; only microhematuria was persistent.
Our diagnosis was SP-HUS. The case in question differs from others described in literature for a very mild renal involvement that contrasts with the severe microangiopathic hemolytic anaemia.
It is hypothesized that various Streptococcus Pneumoniae serotypes with different neuraminidase activity can produce dissimilar manifestation of SP-HUS, ranging from isolated anaemia to full-blown HUS2. This wide spectrum of clinical presentations may cause an underrecognition of SP-HUS, with the risk of administering IgM containing hipouriceblood derivatives. As in our case, invasive Streptococcus Pneumoniae infection associated with anaemia and Coombs¿ positive test, with no sign of DIC, can suggest the proper diagnosis.
