Effects of chelators (desferal, deferiprone & deferaairox) on the growth of klebsiella and aeromonas isolated from transfusion dependent thalassemia patients
Poster Presentation (Doctor’s Session)Infection is among the leading causes of death for
thalassemia major patients. The known predisposing factors
of infection include prior splenectomy, iron overload and
use of iron chelator such as desferal (desferrioxamine).
While encapsulated organisms frequently found in
splenectomized patients were readily controlled by
prophylactic vaccination and vigilant antibiotic treatment,
ferrophilic organisms such as Yersinia and Klebsiella
remains common among Thalassemic patients. The
inductive iron overloaded environment favours the growth
of these organisms but their growth is also affected by the
environment temperature. For example, Yersinia infection
is more prevalent in temperate regions and Klebsiella
infection is commonly found in subtropical areas.
Furthermore, the use of iron chelator in the form of desferal
further aggravates the risk of Yersinia infection. It is because
the iron membrane transport protein siderophore found in
desferal can be adopted by the bacteria for iron acquisition. However, oral chelators such as deferiprone do not enhance
growth of Yersinia in vitro or in vivo. In order to find out
whether such observation can be extended to Klebsiella and
Aeromona infection, in vitro culture assay using Klebsiella
pneumoniae and Aeromonas hydrophila obtained directly
from our transfusion dependent thalassaemic patients were
performed. The growth rates of the bacteria under iron rich,
iron poor with or without different chelators were assessed.
The growth rates were analyzed by both: (1) optic density
of bacterial broth; and (2) colony count by bacterial agar
plate. We found that the growth of Klebsiella was marginally
enhanced by desferal in vitro when compared to Yersinia.
Such unfavourable effect was not found in either deferiprone
or deferasirox in vitro. On the other hand, the growth of
Aeromonas was not affected by the presence of any of the 3
chelators. Therefore, we suggested that factors other than
desferal may account for the increase prevalence of
Klebsiella and Aeromonas infection among Asian
thalassemic patients. It also suggests that oral chelators are
safe for thalassemic patients during febrile illness. Unlike
desferal, withholding iron chelator during infectious period
may not be mandatory. But care has to be exercised
especially for patients on deferiprone, since neutropenia has
to be ruled out during febrile illness.
This project was supported by the Children's Thalassaemia
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