Amoxycillin-resistant streptococci in dental plaque.

This investigation was undertaken to study the prevalence of amoxycillin-resistant oral streptococci in normal healthy patients and patients with a cardiac condition, susceptible to infective endocarditis. Samples of supragingival dental plaque were collected from two test groups, children with congenital heart disease and adults with a history of rheumatic fever, and two control groups comprising normal healthy children and normal healthy adults. Bacteria from these samples were grown on a medium selective for oral streptococci, as well as on the same medium containing known concentrations of amoxycillin. The results indicate that a high percentage of rheumatic heart patients and children with congenital heart disease harboured amoxycillin-resistant oral streptococci. The level of amoxycillin resistance in the plaque of adults with rheumatic heart disease was significantly greater than in that of normal adults. In view of the high percentage of patients at risk harbouring amoxycillin-resistant streptococci, it is important that the individual clinical situation be monitored. Perhaps antibiotic sensitivity tests should be performed to select an appropriate antibiotic for prophylaxis of infective endocarditis.