Antibiotic prophylaxis of endocarditis

Editor, – With regard to the article 'Antibiotic prophylaxis of endocarditis' (Aust Prescr1997;20:11), it is stated that high-risk patients, i.e. prosthetic valve and previous endocarditis, now only need a single (adult) oral dose of 3 gamoxycillin one hour pre-operatively or clindamycin 600 mg (adult) oral dose one hour pre-operatively.

This is a considerable change from the previously recommended antibiotic cover for high-risk patients prior to dental or other procedures, i.e. intravenous amoxycillin 1 g and intravenous gentamicin 1.5 mg/kg with a follow-up oral dose of 500 mg amoxycillin 6 hours later or intravenous vancomycin1 g and intravenous gentamicin 1.5 mg/kg.

Is this change of antibiotic prophylaxis the result of scientific research or a move to provide an easier and cheaper antibiotic cover for these patients? If the latter is the case, this should be of some concern as some cardiologists at St Vincent's Hospital have indicated there is documented evidence of failure of endocarditis protection with oral antibiotic cover.

Ian Hewson
VMO (Dental)
Royal Melbourne Hospital and St Vincent's Hospital
Fitzroy, Vic.

Benafsha Khariwala, the Managing Editor of the Therapeutic Guidelines, comments:
The article which appeared in Australian Prescriber Vol.20 No. 1 1997 on antibiotic prophylaxis of endocarditis only mentioned the standard regimen, i.e. an oral dose of amoxycillin 3 g or clindamycin 600mg, for non-high risk patients undergoing dental procedures without a general anaesthetic.

Dr Hewson's concerns are valid. The 9th edition of the 'Antibiotic Guidelines' (1996) also recommends that `Because the consequences are severe, for high risk patients, i.e. with prosthetic valve or previous infective endocarditis, add gentamicin to the standard or one of the alternative regimens' (intravenous amoxycillin/ampicillin, intravenous vancomycin, intravenous or intramuscularteicoplanin or intravenous clindamycin). For doses, refer to pages 94-5 of the 'Antibiotic Guidelines'.

I hope I have managed to clarify the issue for your readers.

Dr R.G. Woods, Australian Dental Association,

The position of the Australian Dental Association regarding antibiotic prophylaxis for infective endocarditis is that it endorses in principle there commendations set out in the 'Antibiotic Guidelines', 9th edition.

Although different regimens have been recommended in North America and Britain, in Australia we should observe the Australian recommendations.