Effect of topical administration of vancomycin versus chlorhexidine on alpha-hemolytic streptococci in oral cavity

In a crossover study the effect of local vancomycin (paste containing 0.5% vancomycin applied to the gums three times a day for 7 days) versus chlorhexidine mouth rinsing (0.2% chlorhexidine solution twice a day for 7 days) on alpha-hemolytic streptococci in the oral cavity was investigated in eight volunteers. Mixed saliva and dental plaque samples were collected for microbiologic analysis before administration, during treatment, and after withdrawal of the agents. The numbers of different alpha-hemolytic streptococci were determined in the samples. The total numbers of Streptococcus mitior, Streptococcus mutans, and Streptococcus sanguis were significantly reduced by the vancomycin treatment compared with the chlorhexidine treatment (p less than 0.05) after 2 days of administration. Two days after the treatment was stopped the numbers of alpha-hemolytic streptococci had returned to pretreatment levels. Local prophylaxis with vancomycin as a complement to systemic antimicrobial prophylaxis may therefore be useful in the prevention of infective endocarditis.