MOUTH-RINSING WITH CHLORHEXIDINE CAUSES A DELAYED, TEMPORARY INCREASEIN THE LEVELS OF ORAL VIRIDANS STREPTOCOCCI

The indigenous oral flora of 27 Volunteers was monitored longitudinall y over a 4-week period. Bacteria attached on buccal epithelial cells w ere counted by microscopy. Salivary bacterial colonies and the presenc e of alpha-hemolysis were examined after aerobic culturing on blood ag ar plates. The buccal and salivary bacterial counts were stably mainta ined in most subjects in the two repented base line samplings taken at l-week intervals. Rinsing with a chlorhexidine mouthwash 45 min befor e sampling dramatically reduced the amount of epithelial cell-adherent bacteria. One da! after the chlorhexidine rinse. however the numbers of the epithelial cell-adherent bacteria exceeded the base-line level, and a similar decrease-increase pattern of changes was detected for t he salivary alpha-hemolytic streptococcal counts. The non-hemolytic sa livary bacterial counts were not affected by chlorhexidine. Subsequent weekly samplings showed no difference from the base-line samplings. T he chlorhexidine-induced, delayed increase of viridans streptococci on oral epithelial surfaces should be considered a possible risk factor in medically compromised patients.