In patients with a high or medium risk of infectious endocarditis it is important to respect the colonization of the oral cavity by a varied bacterial flora and the ensuing risk of bacteraemia. During every dental treatment of such patients mechanical cleaning and local disinfection of the mouth is essential (e.g. with a 0.12% chlorohexidine solution). Before an invasive dental procedure antibiotic prophylaxis must be administered. With regard to the mixed aerobic-anaerobic microbial flora in the oral cavity we should always assume the possible presence of Actinobacillus actinomycetemcommitans (in particular in concurrent periodontitis) and anaerobic organisms from the Bacteroides group. These microorganisms have a minimal sensitivity to antibiotic prophylaxis recommended by the American Heart Association in 1997. The authors recommend the use of effective antibiotic prophylaxis: amoxicillin combined with metronidazol or an ofloxacin preparation.

        Key words: Actinobacillus actinomycetemcommitans – Bacteroides spp. – amoxicillin – metronidazol – ofloxacin – bacterial endocarditis – antibiotic prophylaxis