Abstract
The mechanism of resistance of Serratia marcescens to chlorhexidine was studied. Two strains of S. marcescens were isolated from the patients at Shinshu University Hospital. One of these strains was resistant to chlorhexidine and the other was sensitive. Minimum bactericidal concentration (MBC) of the resistant strain ((R1) was 4 mg/ml, whereas that of sensitive one (S1) was 0.08 mg/ml. Effects of chlorhexidine on the biosyntheses of macromolecules were comparatively examined on the S1 and R1 strains. The biosyntheses of protein, deoxyribonucleic acid, ribonucleic acid, and lipid in vivo were apparently inhibited by chlorhexidine in the S1 strain within 30s after the addition of chlorhexidine, while those of the R1 strain were not inhibited. Adsorption and permeation of chlorhexidine to the R1 and S1 strain were examined by using [14C]-chlorhexidine. The percent adsorptions of radioactive chlorhexidine onto the intact cells of the R1 and the S1 strain were about 74% and 78%, respectively. The percent distributions of radioactivity in the cell envelope of the R 1 and S 1 strain were about 29% and 42% to the total radioactivity incorporated into the cytoplasm of the R1 and the S1 strain were about 3% and 7%, respectively. These data suggested that membraneous permeability of bacteria played an important role in resistant mechanism.
