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Letter to the Editor

Editor, – In their article on pertussis prophylaxis (Aust Prescr 2012;35:82-4) the authors recommended erythromycin 10 mg/kg (maximum 250 mg) every six hours for children aged two months or more. They make no antibiotic recommendation for children aged one month.

In 1985, good results were observed for pertussis with erythromycin estolate suspension compared to poor results with erythromycin ethyl succinate.1 In the only randomised comparison of the two esters,2 13 of 93 children were cured in the estolate group compared to only 4 of 97 in the ethyl succinate group (p=0.016). Ethyl succinate was given in a dose of 20 mg/kg every eight hours, which is equivalent to 15 mg/kg every six hours rather than the 10 mg/kg every six hours as recommended in the article.

Unfortunately, only erythromycin ethyl succinate suspension is available in Australia. Given the availability of azithromycin, clarithromycin and trimethoprim-sulfamethoxazole, I suggest that erythromycin ethyl succinate suspension should not be recommended for pertussis prophylaxis – and certainly not in a dose of only 10 mg/kg every six hours.

Frank Shann
Specialist in Intensive Care
Royal Children’s Hospital
Melbourne

Professor of Critical Care Medicine
University of Melbourne

Author's comments

Cheryl Jones, one of the authors of the article, comments:

Thank you to Professor Shann for his thoughtful comments about recommendations for erythromycin ethyl succinate suspension. We would like to re-emphasise the main points of our article that only under rare circumstances is antimicrobial prophylaxis indicated, as data to support efficacy and dosing are limited. Azithromycin is the preferred antibiotic for infants.

We made an error in our Table – one-month-old infants were not included. The header of the second column should read less than or equal to one month of age (≤1 month). The Table is based on information from the Australian Immunisation Handbook so the correct reference is reference two.3

The recommended dose of erythromycin 10 mg/kg (maximum 250 mg) every six hours is recommended by the Australian Immunisation Handbook3 and other guidelines.4,5

We agree with the sentiment that erythromycin ethyl succinate is suboptimal for pertussis prophylaxis in infants, not only for efficacy reasons, but also for tolerability (largely gastrointestinal intolerance) and toxicity issues (pyloric stenosis in infants less than one month). Professor Shann has suggested it should not be used at all. We had recommended that its use be considered in the rare circumstances where both the use of prophylaxis is appropriate and azithromycin is not available. Arguably the assistance of public health officers in confirming the need for prophylaxis and sourcing azithromycin would be the best approach.