Antibiotic Prophylaxis in Thalassaemia

The other day, I received a call from a house officer regarding penicillin V dose in thalassaemic children. She was unsure of the indication.


Findings
Splenomegaly (enlarged spleen) is common in thalassaemia major and intermedia due to the high rate of haemolysis (red blood cell destruction). This takes place because the spleen sees the defective red cells of the thalassaemic as deficient and the transfused red cells as invaders (much the same as with host vs graft disease) and removes them from circulation.

In some patients, splenectomy is performed as it may help decrease transfusion requirements for patients with splenomegaly.

The drug of choice for prophylaxis in patients with thalassaemia who have undergone a splenectomy is penicillin. This is because it is active against most microorganisms considered to be major pathogens in splenectomised patients (ie, streptococcal, pneumococcal, and some staphylococcal microorganisms) but not penicillinase-producing species.


Sanford Guide to Antimicrobial Therapy
Asplenic children to have antimicrobial prophylaxis until age 5:
Amoxicillin 20mg/kg/day OR
Penicillin V 125mg bd

Children over age 5:
Penicillin V 250mg bd for at least 1 year in children post-splenectomy

If allergic to penicillin:
-trimethoprim-sulfamethoxazole [National Antibiotic Guidelines states dose as 960mg od] OR
-clarithromycin
[NAG also recommends erythromycin 400mg bd OR azithromycin 250mg od]

The National Antibiotic Guidelines, based on article from BMJ 307, 1372-1373, recommends the duration of treatment to be minimum 2 years post splenectomy in adults and up to 16 years of age in children. Life long is not recommended.



References

1. Sanford Guide to Antimicrobial Thearpy 2006
2. National Antibiotic Guidelines
3. Yaish HM. Thalassaemia Intermedia. Emedicine. 2009 September 29 [Accessed 2010 May 22] Available from: URL: http://emedicine.medscape.com/article/959122-treatment