1990 年 110 巻 6 号 p. 414-425
The mechanisms of resistance of Serratia marcescens and Pseudomonas cepacia to chlorhexidine were studied. Leakage of the cellular component such as protein was observed in a chlorhexidine sensitive strain (S1) of S. marcescens when S1 was treated with chlorhexidine at 40μg/ml concentration, while this phenomenon was not observed in a resistant strain (R1). The following observations were made concerning about cell surface structure in the chlorhexidine sensitive and resistant strains of S. marcescens by chemical analyses of membrane components and electron microscopical studies of the thin sections of the cells. (1) When the S1 strains was treated with chlorhexidine, the outer membrane of the cells formed a wrinkled surface with irregular blebs, and some of which broke out to form various sizes of granules. The R1 strain did not undergo such morphological changes under the same conditions used in the sensitive strain. (2) A prominent protein with apparent molecular weight of 45 K was found exclusively in the R1 strain of S. marcescens as major outer membrane protein, while it was not found in S1 strain. (3) There were no differences in the composition of phospholipids and the amount of 3-hydroxytetradecanoic acid between S1 and R1 strains of S. marcescens. In Pseudomonas cepacia PCJ1 which is resistant to chlorhexidine, 50 K protein was also observed as a major protein of outer membrane of the cells. In contrast to the strain, a mutant of the strain, #102 which was obtained from PCJ1 strain by the treatment with methanesulfonic acid ethylester, did not possese the 50 K protein in its outer membrane. These data suggested that outer membrane components of bacteria were related importantly in resistant mechanism.