Which patients should receive antibiotic prophylaxis for endocarditis, and which procedures should be covered in this way?

There is little firm scientific evidence for present advice on antibiotic prophylaxis for endocarditis, mainly because of the rarity of the disease. Only 10% of cases are related to bacteraemia caused by invasive procedures. Prevention of endocarditis in patients with abnormal heart valves can be achieved by many general measures, for example, regular dental care. The convention for the use of antibiotics in the prevention of endocarditis derives from animal models and clinical experience. Although dental extraction results in a bacteraemia of about 100cfu/mL, no obvious relationship has been found between the number of circulating bacteria and the likelihood of developing endocarditis.

In man, case-control studies suggest 17% of cases might be prevented if prophylaxis is given for all procedures in patients with abnormal valves.1 Individual cases of endocarditis following dental or urological procedures have been reported but the risk of developing endocarditis must be very low. Underlying cardiac abnormalities greatly increase the risk of endocarditis, e.g. patent ductus arteriosus, prosthetic valves, hypertrophic cardiomyopathy, aortic valve disease or previous endocarditis.
Mitral valve prolapse is common but merits antibiotic prophylaxis if it causes a murmur.

Procedures causing gingival bleeding should be covered by prophylaxis as should tonsillectomy, adenoidectomy and dental work. Other procedures in which prophylaxis should be used include oesophageal dilatation or surgery or endoscopic laser procedures, sclerosis of oesophageal varices, abdominal surgery, instrumentation of ureter or kidney, surgery of prostate or urinary tract. Flexible bronchoscopy with biopsy, cardiac catheterisation, endoscopy with biopsy, liver biopsy, endotracheal intubation and
urethral catheterisation in the absence of infection do not need prophylaxis. Patients having colonoscopy or sigmoidoscopy probably do not require prophylaxis unless there is a prosthetic valve or previous endocarditis or unless biopsy is likely to be performed. Recommendations for prophylaxis in patients undergoing obstetric or gynaecological procedures are required for patients with prosthetic valves, or who have previously had endocarditis.

Recommendations for prophylaxis vary between countries. Dental (causing gingival bleeding), oropharyngeal, gastrointestinal and urological procedures are usually considered a risk.2 The use of antibiotic prophylaxis is routine during cardiac surgery, flucloxacillin, plus an aminoglycoside, or a cephalosporin being common choices.