Experiences with HUS in Canada: what have we learned about childhood HUS in Canada?

Genotypic Features of Clinical and Bovine Escherichia coli O157 Strains Isolated in Countries with Different Associated-Disease Incidences

There is great geographical variation in the frequency of Escherichia coli O157 infections that correlates with important differences in the bovine reservoir of each country. Our group carried out a broad molecular characterization of human and bovine E. coli O157 strains circulating in Argentina using different methodologies. Our data allows us to conclude that in Argentina, a high homogeneity is observed in both cattle and human strains, with almost exclusive circulation of strains belonging to the hypervirulent clade 8 described by Manning. The aim of this review was to compare the genetic background of E. coli O157 strains isolated in countries that have conducted similar studies, to try to correlate specific O157 genotypes with the incidence and severity of E. coli O157 associated diseases. The characteristics of the strains that cause disease in humans reflect the predominant genotypes in cattle in each of the countries analyzed. The main features clearly linked to high incidence or severity of E. coli O157 infections are lineage-specific polymorphism assay-6 lineage I/II, clade 8 strains and probably, clade 6 strains, the stx_2a/stx_2c genotype, the presence of q933 and q21 simultaneously, and putative virulence factor EC_3286. In countries with an absence of these features in O157 strains, the overall incidence of O157 disease is low. Argentina, where these characteristics are detected in most strains, shows the highest incidence of hemolytic uremic syndrome (HUS) worldwide.

Postinfectious Hemolytic Uremic Syndrome

Post-infectious hemolytic uremic syndrome (HUS) is caused by specific pathogens in patients with no identifiable HUS-associated genetic mutation or autoantibody. The majority of episodes is due to infections by Shiga toxin (Stx) producing Escherichia coli (STEC). This chapter reviews the epidemiology and pathogenesis of STEC-HUS, including bacterial-derived factors and host responses. STEC disease is characterized by hematological (microangiopathic hemolytic anemia), renal (acute kidney injury) and extrarenal organ involvement. Clinicians should always strive for an etiological diagnosis through the microbiological or molecular identification of Stx-producing bacteria and Stx or, if negative, serological assays. Treatment of STEC-HUS is supportive; more investigations are needed to evaluate the efficacy of putative preventive and therapeutic measures, such as non-phage-inducing antibiotics, volume expansion and anti-complement agents. The outcome of STEC-HUS is generally favorable, but chronic kidney disease, permanent extrarenal, mainly cerebral complication and death (in less than 5 %) occur and long-term follow-up is recommended. The remainder of this chapter highlights rarer forms of (post-infectious) HUS due to S. dysenteriae, S. pneumoniae, influenza A and HIV and discusses potential interactions between these pathogens and the complement system.

Hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is a clinical syndrome characterized by the triad of thrombotic microangiopathy, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome represents a heterogeneous group of disorders with variable etiologies that result in differences in presentation, management and outcome. In recent years, better understanding of the HUS, especially those due to genetic mutations in the alternative complement pathway have provided an update on the terminology, classification, and treatment of the disease. This review will provide the updated classification of the disease and the current diagnostic and therapeutic approaches on the complement-mediated HUS in addition to STEC-HUS which is the most common cause of the HUS in childhood.

Hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is a clinical syndrome characterized by the triad of thrombotic microangiopathy, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome represents a heterogeneous group of disorders with variable etiologies that result in differences in presentation, management and outcome. In recent years, better understanding of the HUS, especially those due to genetic mutations in the alternative complement pathway have provided an update on the terminology, classification, and treatment of the disease. This review will provide the updated classification of the disease and the current diagnostic and therapeutic approaches on the complement-mediated HUS in addition to STEC-HUS which is the most common cause of the HUS in childhood.

[Microalbuminuria in pediatric patients diagnosed with hemolytic uremic syndrome]

INTRODUCTION

Hemolytic uremic syndrome (HUS) is characterized by the presence of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney failure. It is the leading cause of acute kidney failure in children under 3 years of age. A variable number of patients develop proteinuria, hypertension, and chronic renal failure.

OBJECTIVE

To evaluate the renal involvement in pediatric patients diagnosed with HUS using the microalbumin/creatinine ratio.

PATIENTS AND METHODS

Descriptive concurrent cohort study that analyzed the presence of microalbuminuria in patients diagnosed with HUS between January 2001 and March 2012, who evolved without hypertension and normal renal function (clearance greater than 90ml/min using Schwartz formula). Demographic factors (age, sex), clinical presentation at time of diagnosis, use of antibiotics prior to admission, and need for renal replacement therapy were evaluated.

RESULTS

Of the 24 patients studied, 54% were male. The mean age at diagnosis was two years. Peritoneal dialysis was required in 45%, and 33% developed persistent microalbuminuria. Antiproteinuric treatment was introduce in 4 patients, with good response. The mean follow-up was 6 years (range 6 months to 11 years). The serum creatinine returned to normal in all patients during follow up.

CONCLUSIONS

The percentage of persistent microalbuminuria found in patients with a previous diagnosis of HUS was similar in our group to that described in the literature. Antiproteinuric treatment could delay kidney damage, but further multicenter prospective studies are necessary.