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Some details of 544 episodes of infective endocarditis occurring in 541 patients during 1981 and 1982 are reported. The mean age of patients was 51.6 years and there was a greater proportion of males (2:1). Of the 544 episodes 347 (63%) were due to streptococci, 19% to staphylococci, and 14% to bowel organisms. A wide variety of other organisms were responsible for a few cases, and 10% were culture negative. In 60% the portal of entry of the infection could not be ascertained: 19% were probably of dental origin: 16% arose from the alimentary, genitourinary, or respiratory tracts or from the skin or in association with drug addiction, fractures, or pregnancy; the remaining 5% were related to cardiac or other vascular surgery, cardiac catheterisation, haemodialysis, or other procedures involving the blood stream. Seventy-four (14%) of the 541 patients (mean age 59.0 years) died; the mortality was 30% in staphylococcal cases, 14% in infections due to bowel organisms, and 6% in other streptococcal infections. One hundred and seventy-one (32%) of the patients appeared to have had normal hearts before the onset of illness and another 59 (11%) had cardiac lesions not previously recognised. The aortic valve was the most common site of infection. Ninety (17%) of the patients had prosthetic valves or had undergone other cardiac surgery while 34 (6%) had had a previous episode of infective endocarditis. Nine (1.6%) episodes were not diagnosed until necropsy or operation and 34 (6.3%) required urgent valve replacement.

During 1981 and 1982 544 cases of infective endocarditis were investigated retrospectively by means of a questionnaire. Only 13.7% had undergone any dental procedure within three months of the onset of the illness, and in 42.5% there was no known cardiac abnormality before the onset of the disease. Furthermore, the number of cases occurring annually was about the same as or more than it was before the introduction of penicillin. The mouth and nasopharynx were the most likely sources of the commonest organism, Streptococcus viridans, and it is suggested that it is not dental extractions themselves which are of importance but good dental hygiene. In most patients with infective endocarditis the portal of entry of the organism whatever its nature cannot be identified. If this is so antibiotics are being given to only a small proportion of those at risk, and this would explain why the number of cases is much the same as it was before the introduction of penicillin. Furthermore, the large proportion of patients with no known previous cardiac abnormality adds to the difficulty of providing effective prophylaxis. The evidence suggests that antibiotic prophylaxis should still be given before dental procedures, and a schedule is appended. Much more importance should be given, however, to encouraging people to seek better routine dental care. We also believe that doctors and dentists should appreciate that the pattern of the disease has changed considerably in the past 50 years and that the information given here warrants a revised approach to the problem.