Chlorhexidine affects arginine metabolism as well as glycolysis in a strain of Streptococcus sanguis

Abstract

Abstract The effect of Chlorhexidine digluconate (CHX) on the uptake and catabolism of arginine (arg) by Streptococcus sanguis P4A7 was investigated since the ability to use this amino acid may play a role in its existence in dental plaque. Organisms were grown glucose-limited in continuous culture in a chemically-defined medium. Washed cells, resuspended in a salt solution, were exposed to various concentrations of CHX prior to the addition of arg. Uptake of arginine and the appearance of its catabolites were monitored by HPLC analysis of cell suspension filtrates. At pH 7.0 and 5.5, both uptake and breakdown were progressively reduced by 0.06 and 0.12 mM CHX and these effects were even more marked in the presence of 0.24 mM CHX, which also reduced cell viability. The glycolytic rate was also progressively reduced as the level of CHX was raised from 0.06 to 0.24 mM. The arginine deiminase pathway, as well as glycolysis, is thus depressed by sub-inhibitory concentrations of CHX and it is suggested that this could have far-reaching effects on overall plaque metabolism.