A Case of Yersinia Enterocolitica Sepsis in a Beta Thalassemia Patient on Deferasirox

Thalassemias are a geographically widespread group of genetic hemoglobinopathies characterized by defective globin production and hemolytic anemia [1]. Thalassemic patients are frequently transfusiondependent and this, in addition to heightened gastrointestinal avidity for iron, creates a propensity for iron overload [1]. Infection is a major cause of morbidity in thalassemic patients and is second only to hemosiderin cardiomyopathy as a cause of mortality [1]. Transfusion predisposes patients to infection, both directly as a consequence of horizontal transmission of bloodborne infection from donor to recipient, and as a result of iron overload itself which is an independent risk factor for infection [1,2]. Specifically, iron overload confers susceptibility to Yersinia enterocolitica, Yersinia pseudotuberculosis, Klebsiella spp., Escherichia coli, Streptococcus pneumoniae, Vibrio vulnificus, Pseudomonas aeruginosa, Listeria monocytogenes, and Legionella pneumophila [1,3]. Desferrioxamine has long been administered parenterally as an iron chelating agent to patients with iron overload, however, it adds to the risk of infection by Y. enterocolitica [1]. This is because although Y. enterocolitica lacks high-affinity iron chelating siderophores to allow it to take up iron from the environment in typical hosts, it is able to bind desferrioxamine and utilize it to achieve more efficient iron uptake [1,4]. Consequently, there are multiple case reports in the literature of serious Y. enterocolitica infections in thalassemic patients treated with desferrioxamine [4-8]. Deferasirox is a newer iron chelating agent which is administered orally. This mode of administration has led to increasing use of deferasirox in place of desferrioxamine to mitigate iron overload. In vitro comparative studies with Klebsiella pneumoniae and V.vulnificus, both organisms whose growth is augmented by high-iron environments, demonstrated enhanced pathogen growth with desferrioxamine, but not with deferasirox [3,9]. Although no such studies were performed with Y. enterocolitica, it would have been thought that similar findings could have been found with this similar iron-avid organism. Furthermore, to our knowledge, there are as yet no documented cases of Yersinia sepsis in a thalassemic patient treated with deferasirox.