Influence of suspending media upon the susceptibility of Pseudomonas aeruginosa NCTC 6750 and its spheroplasts to polymyxin B. 1979

R M Klemperer, and P Gilbert, and A M Meier, and R M Cozens, and M R Brown

The lytic and bactericidal actions of polymyxin B on whole cells and spheroplasts of Pseudomonas aeruginosa varied markedly with the suspending media, and there was little correlation between them. Relative rates of lysis of these preparations and also of Bacillus megaterium protoplasts suggested that polymyxin causes progressive damage to the cytoplasmic membrane, such that membrane permeability towards various ions increased as follows: K(+) > Na(+) > NO(3) (-) > Cl(-), Ca(2+), H(2)PO(4) (-)/HPO(4) (2-). Impermeant compounds, such as NaCl and sucrose, protected whole cells against lysis but not against death. It is suggested that lysis of whole cells by polymyxin is a secondary effect, resulting from entry of solutes normally excluded by the cytoplasmic membrane and the fragility of the damaged outer membrane. Because the degree of lysis varies with the external solutes, it should be treated with caution as a descriptor of polymyxin activity.

UI MeSH Term Description Entries
D011112 Polymyxin B A mixture of polymyxins B1 and B2, obtained from BACILLUS POLYMYXA strains. They are basic polypeptides of about eight amino acids and have cationic detergent action on cell membranes. Polymyxin B is used for treatment of infections with gram-negative bacteria, but may be neurotoxic and nephrotoxic. Aerosporin,Polymyxin B Sulfate
D011113 Polymyxins Basic lipopeptide antibiotic group obtained from Bacillus polymyxa. They affect the cell membrane by detergent action and may cause neuromuscular and kidney damage. At least eleven different members of the polymyxin group have been identified, each designated by a letter. Polymyxin,Polymyxin M
D011523 Protoplasts The protoplasm and plasma membrane of plant, fungal, bacterial or archaeon cells without the CELL WALL. Protoplast
D011550 Pseudomonas aeruginosa A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. aeruginosa is a major agent of nosocomial infection. Bacillus aeruginosus,Bacillus pyocyaneus,Bacterium aeruginosum,Bacterium pyocyaneum,Micrococcus pyocyaneus,Pseudomonas polycolor,Pseudomonas pyocyanea
D003470 Culture Media Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN. Media, Culture
D001410 Bacillus megaterium A species of bacteria whose spores vary from round to elongate. It is a common soil saprophyte. Bacillus megatherium
D013104 Spheroplasts Cells, usually bacteria or yeast, which have partially lost their cell wall, lost their characteristic shape and become round. Spheroplast
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor

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