Streptococcus pneumoniae-induced haemolytic uraemic syndrome

Follow-up of children with infection-associated haemolytic uraemic syndrome 1979-1995: Would eculizumab have improved prognosis?

The late outcome in 55 children with infection-mediated haemolytic uremic syndrome (Shiga Toxin E Coli (STEC)-HUS and pneumococcal HUS) observed in 1979-1995 was followed up 23 years after disease onset. Of these, two were later confirmed to have atypical HUS (aHUS). Furthermore, of this population, five children had impaired kidney function at 3-months follow-up, which continued to deteriorate. These children had significant oliguria/anuria and hypertension during their illness requiring early dialysis and antihypertensive therapy. At 23 years post-disease onset, all five (100%) of these children have developed end-stage kidney disease or chronic kidney disease. Eculizumab is a monoclonal antibody that binds with high affinity to the C5 protein of the complement pathway, a major component of the pathophysiology of infection-mediated HUS. There are no long-term randomised controlled trials in the literature to support its use in such cases. Our 23-year follow-up of a population of severely affected children with infection-mediated HUS demonstrates a high percentage of chronic kidney disease and end-stage kidney disease (19%). Randomised controlled trials with eculizumab are now being conducted in this affected cohort.

Diagnosis of Streptococcus pneumoniae-associated hemolytic uremic syndrome

BACKGROUND

Hemolytic uremic syndrome related to pneumococcal infection (P+HUS) can be difficult to diagnose due to the lack of a specific test and the absence of a consensus for definite diagnostic criteria.

METHODS

A retrospective study was conducted on the cases that have been considered as P+HUS in the participating centers during the past 10 years. Diagnostic strategy and criteria used for the diagnosis of P+HUS were evaluated and compared with a review of literature data.

RESULTS

A total of 17 children were studied. Tests ruling out other causes of HUS were performed in 94% of cases. Direct confirmatory tests for P+HUS were done in a minority of cases as Thomsen-Friedenreich antigen testing using lectin assay were done in only 2 patients (11%). Retrospectively, the diagnosis of P+HUS was confirmed in 28% to 89% of cases depending on the already published criteria used. A literature review focused on the last 15 years confirmed these diagnostic difficulties due to variable definition criteria and bring a new light on the potential usefulness of tests used to reveal T activation in this setting.

CONCLUSION

To date, in a context of suspicion of P+HUS, no precise, practical and consensual strategy exists for T-antigen exposure diagnosis. The T-antigen activation test using peanut lectin might be the most appropriate test for a direct diagnosis of P+HUS. A large prospective study is required to confirm this hypothesis. However, before such data are available, its use could be of help when a suspicion of P+HUS is present given the therapeutic impact of such a diagnosis.

Invasive Streptococcus pneumoniae infection causing hemolytic uremic syndrome in children: Two recent cases

INTRODUCTION

Streptococcus pneumoniae is an uncommon cause of hemolytic uremic syndrome (HUS) with a unique pathophysiology that differs from Shiga toxin-related HUS.

METHODS

Case descriptions for each patient are provided. Each strain of S pneumoniae was subjected to a pulsed-field gel electrophoresis (PFGE) analysis, Shiga toxin assay and polymerase chain reaction to detect Shiga toxin genes. A review of the current literature was conducted.

CASE PRESENTATIONS

Two patients with S pneumoniae-related HUS that presented to the Alberta Children's Hospital, Calgary, Alberta, within four weeks of each other in 2001 are described. Both presented with pneumonia and empyema with associated HUS. Both patients required dialysis, one patient for 10 days and the other for 18 days. Neither patient demonstrated evidence of Shiga toxin-related disease. S pneumoniae isolated from blood or pleural fluid was penicillin susceptible. One isolate was serotype 3 and the other was serotype 14. The two strains had different PFGE patterns. Both patients recovered well with no persistent renal dysfunction.

CONCLUSIONS

S pneumoniaecontinues to be an uncommon but important cause of HUS. Most cases can be confirmed or at least considered probable without performing a renal biopsy.

Pneumococcal Induced T-activation with Resultant Thrombotic Microangiopathy

Thrombotic microangiopathies are disorders resulting from platelet thromboses forming in the microvasculature with resultant schistocyte forms. Hemolytic uremic syndrome (HUS) is a microangiopathic hemolytic anemia often complicated by acute renal failure in children. HUS is typically caused by bacterial infection, most commonly enterohemorrhagic Escherichia coli. Neuraminidase-producing organisms, such as Streptococcus pneumoniae have also been reported as potential etiologies. The pathogenesis in these cases involves cleavage of sialic acid residues from the surfaces of erythrocytes, platelets, and glomerular capillary endothelial cells, exposing the Thomsen-Friedenreich antigen, a process known as T-activation. We describe a 2-year-old girl who presented with pneumococcal pneumonia and sepsis ultimately resulting in a thrombotic microangiopathy with acute renal failure, most consistent with HUS. The patient’s direct antiglobulin test was positive. Polyagglutination was observed with human adult serum, but not with umbilical cord serum. Her red blood cells (RBCs) were reactive against peanut and soybean lectins, but not Salvia sclarea or Salvia horminum lectins. These findings are consistent with T-activation. Clinicians should be cognizant of the possibility of T-activation with resultant HUS in patients infected with neuraminidase-producing bacteria. Such patients may be difficult to identify using monoclonal typing antisera, as these typically do not have anti-T antibodies. Whether such patients are at risk for transfusion-associated hemolysis is debatable.

Ten years of pneumococcal-associated haemolytic uraemic syndrome in New Zealand children

AIM

To describe the epidemiology, clinical features, management and outcome of pneumococcal-associated haemolytic-uraemic syndrome (P-HUS) in New Zealand over the past decade.

METHODS

A retrospective chart review of children with P-HUS from 1998 to 2007 that were prospectively reported to the New Zealand Paediatric Surveillance Unit. P-HUS was defined as microangiopathic haemolytic anaemia (Hb <100 g/L with fragmented red blood cells), thrombocytopaenia (platelet count <130 x 10(9)/L), acute renal impairment with oliguria and elevated plasma creatinine, and confirmed or suspected pneumococcal infection.

RESULTS

Eleven children (nine male, two female), predominately Maori and Polynesian (10 children) were studied. The median age was 8.5 months. The median duration of hospitalisation was 25 days. Of the infections, 10 were confirmed pneumococcal (six pneumonia, four meningitis) and one pneumonia was suspected pneumococcal (culture negative, however T activation positive). Nine patients required dialysis for a median duration of 13 days. One child with meningitis died after therapy was withdrawn because of severe neurological injury. One patient developed end stage kidney disease and two further children had evidence of persisting renal sequelae at follow-up.

CONCLUSIONS

Pneumococcal disease remains an important public health problem in New Zealand children, particularly those of Maori and Pacific Island ethnicity. P-HUS should be considered in pneumococcal disease associated with severe haematological and renal abnormalities. These children should be monitored long-term, as they are at risk of permanent renal injury.

Streptococcus pneumoniae-associated hemolytic uremic syndrome

Streptococcus pneumonia-associated hemolytic uremic syndrome (HUS) (pneumococcal HUS) is an uncommon condition mainly observed in young children. Early recognition is critical, because of the potential to improve morbidity and mortality. In our review we summarize the pathophysiology, clinical features, diagnostic difficulties and management of this potentially under-diagnosed condition.

Hemolytic uremic syndrome associated with invasive pneumococcal disease: the United kingdom experience

OBJECTIVE

To describe the presentation, management, and outcome of 43 cases of pneumococcal-associated hemolytic uremic syndrome (P-HUS). An increased incidence of P-HUS has been noted in the United Kingdom between January 1998 and May 2005.

STUDY DESIGN

Cases with microangiopathic hemolytic anemia (Hb <10 g/dL with fragmented RBCs), thrombocytopenia (platelet count < 130 x 10(9)/L), acute renal impairment with oliguria and elevated plasma creatinine for age, confirmed or suspected pneumococcal infection and/or T-activation were included.

RESULTS

The median age at presentation was 13 months (range, 5-39 months). Pneumococcus was identified in 34 of 43 cases; T-activation was identified in 36 of 37 cases. Twelve strains were serotyped: serotypes 3 (n = 2), 6A (n = 2), 12F (n = 1), 14 (n = 1), 19A (n = 6). Empyema was present in 23 of 35 pneumonia cases; 13 cases had confirmed (9) or suspected (4) pneumococcal meningitis; 36 cases required dialysis (median, 10 days; range, 2-240 days). The mortality rate was 11%, comprising 3 cases of meningitis, 1 case of sepsis and 1 case of pulmonary embolism at 8 months follow up while on dialysis. Follow-up data were available for 35 of 38 patients who survived (median follow-up period, 9 months; range, 1-63 months); of these, 10 patients had renal dysfunction, 1 patient was dialysis-dependent, 5 patients had hypertension and 8 patients had at least 1+ proteinuria on urinalysis.

CONCLUSION

P-HUS has increased compared with historic surveys (0/288 in 1985-1988; 8/413 in 1997-2001, 43/315 in 1998-May 2005). Early mortality remains high (8-fold that of VTEC-induced HUS). Ten of 12 strains identified would not be covered by the PCV7 vaccine.

T-antigen activation for prediction of pneumococcus-induced hemolytic uremic syndrome and hemolytic anemia

BACKGROUND

Among the most severe complications of invasive pneumococcal infection are hemolytic uremic syndrome (P-HUS) and hemolytic anemia (P-HA), which occur when the Thomsen-Freidenreich antigen (TA) is exposed on erythrocytes, platelets and glomeruli.

METHODS

To determine the positive predictive value, sensitivity, and specificity of early TA activation testing for P-HUS or P-HA and to compare the microbiologic features of pneumococcus isolates associated or not associated with TA activation. The case records for 36 patients with invasive pneumococcal infection who had been tested for TA activation were retrospectively reviewed. Clinical and laboratory data were compared between patients with and without TA activation.

RESULTS

Positive TA activation was 86% sensitive and 57% specific for P-HUS or P-HA. The positive predictive value was 76%. There were no between-group differences in antibiotic susceptibility of the pneumococcal isolates. Pneumococcal serotype 14 was the most frequent (5/10 isolates tested) serotype causing P-HUS. Of the 36 patients, 13 required packed red blood cell transfusion, 3 died, and 2 required extracorporeal membrane oxygenation. No patient had long-term renal sequelae.

CONCLUSIONS

TA activation is a reasonable predictor of P-HUS or P-HA and could be useful if tested soon after invasive pneumococcal disease is first diagnosed.

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.

Invasive pneumococcal disease and hemolytic uremic syndrome

OBJECTIVE

Severe pneumococcal infections have been associated with hemolytic uremic syndrome (HUS), usually with a poor clinical outcome when compared with Escherichia coli O157 gastroenteritis-associated (D+) HUS. We examined our experience with 12 cases of Streptococcus pneumoniae-associated HUS (SP-HUS) and compare it with a cohort of diarrhea-associated HUS (D+ HUS).

METHODS

A retrospective case survey compared 2 unrelated groups of HUS patients. Demographic factors, clinical indices of disease severity, and outcome were used to compare the 2 groups of HUS patients.

RESULTS

Twelve children with SP-HUS were studied. Pneumococcal pneumonia with empyema was the most common precipitating illness (67%), pneumococcal meningitis was present in 17% of children, pneumonia with bacteremia in 8%, and both pneumonia and meningitis in 8%. SP-HUS patients were younger than D+ HUS patients (22.1 vs 49 months) and had more severe renal and hematologic disease than D+ HUS patients. Compared with D+ HUS patients, SP-HUS patients were more likely to require dialysis (75% vs 59%) and had a longer duration of hospitalization (33.2 vs 16.1 days) and duration of thrombocytopenia (11.6 vs 6.8 days). SP-HUS patients were also more likely to require platelet transfusions (83% vs 47%) and needed more platelet (4.7 vs 0.5) and packed red blood cell transfusions (7.8 vs 2.0). The 2 groups did not differ significantly in the incidence of extrarenal HUS complications. There were no deaths in either group. Seven patients have been seen for long-term follow-up; 2 developed end-stage renal disease, and 5 have normal renal function.

CONCLUSIONS

HUS is a rare but severe complication of invasive pneumococcal infection. Although disseminated intravascular coagulation can also occur in these children, the treatment and follow-up may be different in the 2 conditions. Children with pneumococcal disease and severe hematologic or renal abnormalities should be investigated for evidence of HUS.

Plasma exchange as successful treatment of thrombotic thrombocytopenic purpura post autologous bone marrow transplant in a child

We describe the case of a small child with stage IV neuroblastoma who developed thrombotic thromobocytopenic purpura (TTP) post autologous bone marrow transplant. Pneumococcal sepsis may have been the cause, a previously unreported association in transplant-associated TTP. Despite the child's size (10 kg) and the severity of the disease early intensive treatment with whole blood exchange and subsequently plasma exchange with cryosupernatant proved to be rapidly effective, in contrast to previous reports on its ineffectiveness in this setting.