Rheumatic Fever Chemoprophylaxis and Penicillin-Resistant Gingival Organisms

Penicillin-resistant gingival organisms occur in patients on oral penicillin rheumatic fever chemoprophylaxis. Gingival organisms of 87 patients undergoing chemoprophylaxis were compared with those of controls not receiving chemoprophylaxis. Ten percent of patients receiving sulfadiazine prophylaxis, 42% receiving oral penicillin prophylaxis, 5% receiving benzathine penicillin prophylaxis, and 23% of controls had penicillin-resistant gingival organisms. Fourteen percent of the gingival flora of patients on oral penicillin prophylaxis were penicillin-resistant, a much greater percentage than that in the other three groups. Change of prophylaxis from sulfadiazine to oral penicillin caused an increase in penicillin-resistant organisms; when penicillin prophylaxis was discontinued and sulfadiazine prophylaxis resumed, these organisms decreased. Penicillin-resistant organisms included alpha streptococci, staphylococci, and micrococci; most were sensitive to erythromycin and lincomycin. Penicillin-resistant gingival organisms associated with oral penicillin prophylaxis may influence the choice of antibiotic for the prevention of bacterial endocarditis at the time of dental procedures.