The hemolytic uremic syndrome: a possible etiological role of Campylobacter infection

Abstract

Hemolytic uremic syndrome (HUS), one of the forms of thrombotic microangiopathy, is a severe emergency with non-immune (Coombs negative) anemia, thrombocytopenia and acute renal injury. HUS is heterogeneous, and its most common form, the typical HUS, is associated with Shiga toxin (Stx) producing bacteria, such as Escherichia coli, Shigella dysenteriae, and Citrobacter freundii. Less frequent is HUS, caused by a neuraminidase producing streptococcus (pneumococcal HUS). The most uncommon form is the atypical HUS, which is a genetic orphan disease associated with an abnormality in the regulatory protein of the complement system. HUS has a fairly high mortality rate, amounting to 10–15% on average. The long-term outcomes of HUS depend on its type, as well as on the degree of the primary body tissue damage. According to the data from Novosibirsk Children's Municipal Clinical Hospital No 3 from 1991, 44 cases of HUS in children have been identified. Complete recovery, without any residual abnormalities, was registered in 25 children (56.8% of the cases). Nine children (20.5%) developed chronic kidney disease and 10 (22.7%) of all HUS cases were fatal. Early diagnosis, as well as the identification of pathogenetic mechanisms, is the basis for adequate therapy and outcome prediction. Campylobacter may be one of the causative agents of HUS. Despite new cases of Campylobacter-associated HUS being registered in the world, the very possibility of HUS induction by this pathogen and its pathophysiology are currently unclear. There is no convincing evidence for both Stx and the neuraminidase-related mechanism of HUS in Campylobacter infections. Given the high incidence of autoimmune disorders like Guillain-Barre syndrome and reactive arthritis in Campylobacter infections, it is currently impossible to exclude an autoimmune mechanism of HUS in these diseases. Thus, the role of Campylobacter, as a new potential bacterial agent of HUS, as well as the pathogenesis of such conditions in Campylobacter infections, requires further study.