RELATIONSHIP OF SURFACTANT PROPERTIES OF SOME SYNTHETIC STEROIDS TO BACTERICIDAL ACTION

Application of the Ferguson principle to the antimicrobial activity of quaternary ammonium salts

The activity of three quaternary ammonium salts, dodecyltrimethylammonium chloride, dodecyldimethylethylammonium chloride and dodecylpyridinium chloride, against M. aureus, E. coli and C. albicans has been determined and correlated with the surface properties of these compounds. The Ferguson principle has been applied by using surface concentration to estimate thermodynamic activity. Results obtained for the three quaternary ammonium salts and a particular micro-organism species were found to be in good agreement with each other when microbiological and surface studies were conducted under identical conditions.

Evaluation of various N-substituted azaspiranedione derivatives as potential antimicrobial agents

A series of N-substituted hydrazines were condensed with various spiro[4.5] and [5.5] anhydrides and the resultant N-substituted azaspiranediones were evaluated for antimicrobial activity. None displayed any significant activity in a variety of organisms tested.

The biology of the gonococcus

Gonorrhea has been known since antiquity. Today, this disease is the most commonly reported infectious disease in the U.S. The natural environment of the etiological agent, Neisseria gonorrhoeae, is man. In this host, the organism usually parasitizes mucosal surfaces populated by columnar epithelial cells. Under certain conditions, the gonococcus may disseminate or spread to adjacent organs. The gonococcus is well adapted to its environment and is a successful parasite. Until recently, gonococci were uniformly sensitive to penicilin. However, a plasmid encoding beta-lactamase has been identified in some isolates. Most strains exhibit specific requirements for various amino acids, vitamins, purines, and pyrimidines. Only glucose, pyruvate, and lactate are utilized as sources of energy. Glucose is dissimilated by a combination of the Entner-Doudoroff and pentose phosphate pathways. A tricarboxylic acid cycle is also present and active under certain conditions. Structurally, the cell envelope of the gonococcus resembles that of a typical Gram-negative bacterium. Gonococci are highly autolytic, especially in older cultures or after depletion of the energy source. Autolysis is not due solely to peptidoglycan hydrolysis, but appears to involve a destabilization of the outer membrane as well. Cell surface components such as pili, lipopolysaccharide, outer membrane proteins, and a capsule are associated with the virulence and pathogenicity of this organism.

Effect of progesterone on Neisseria gonorrhoeae

The effects of progesterone on the growth of pathogenic and nonpathogenic species of Neisseria were studied in liquid cultures. Only strains of N. gonorrhoeae and N. meningitidis were highly sensitive to growth inhibition by progesterone. This inhibitory effect was either bacteriostatic or bactericidal, depending upon the ratio of progesterone concentration to cell mass. The site of progesterone inhibition appeared to be located in the cell membrane; >86% of [4-(14)C]progesterone was recovered in the lipid-containing cell fractions. Membrane preparations from N. gonorrhoeae bound progesterone more efficiently than those from progesterone-insensitive cells. In addition, progesterone significantly inhibited the activity of the membrane-associated enzymes reduced nicotinamide adenine dinucleotide oxidase and (cytochrome b) l-lactate dehydrogenase.

Effect of azasteroids on gram-positive bacteria

A group of nitrogen-containing steroids closely related in structure was screened for antibacterial activity, by use of Bacillus subtilis and Sarcina lutea as the test organisms. The most active compounds were cholesterol derivatives containing a tertiary or quaternary nitrogen in, or attached to, the A ring. Similar methyltestosterone or progesterone derivatives were inactive. All of the cholesterol derivatives that inhibited growth were surfactant, and, structurally, they would be classified as cationic detergents. Some of the inactive compounds were surfactant, but, structurally, they would be classified as nonionic detergents. Certain features of the antibacterial activity of one of the active steroids-ND 212 (4-dimethylaminoethyl-4-aza-5-cholesten-3-one methiodide)-were studied. Growth of a culture of B. subtilis containing 5 x 10(7) cells per milliliter was inhibited by 1 mug/ml (1.7 x 10(-6)m) of ND 212. The amount of growth inhibition was directly related to both cell and steroid concentration. Loss of viability was rapid and irreversible. With B. subtilis, cell lysis was observed. With S. lutea grown in C(14)-glucose, ND 212 caused release into the media of up to 25% of the cellular radioactivity. Extensive leakage occurred before loss of viability was observed. At bacteriostatic azasteroid concentrations, there was little leakage. ND 212 was readily bound in large amounts to B. subtilis cells. Inactive azasteroids were bound poorly. C(14)-cholestanone was also bound, whereas C(14)-methyltestosterone and C(14)-progesterone were not bound in significant amounts. At least 50% of the bound C(14)-cholestanone was associated with the membrane fraction.

Steroid lysis of protoplasts and effects of stabilizers and steroid antagonists

Six synthetic antimicrobial steroids were examined for indications of their mechanism of action. Dequadin acetate, cetyl pyridinium chloride (CPC), and sodium deoxycholate were studied for comparison. Aerated cells of Sarcina lutea were washed, suspended in 1.06 M sucrose, and converted to protoplasts with 20 mug/ml of lysozyme. Lysis was measured optically at 650 mmu as a decrease in optical density. Screening tests with 50 mug/ml of each compound showed five steroids and CPC to be lytic. Protoplasts were strongly protected from lysis by pretreatment with 0.001 to 0.004 M spermine tetrahydrochloride. Other polyamines, such as spermidine phosphate, were less protective, and putrescine was ineffective. Uranyl nitrate (5 x 10(-4) M) rapidly agglutinated protoplasts and protected them from rupture by the lytic agents. Similar studies with 0.001 to 0.004 M Mg(++) showed varying degrees of protection, which, in most cases, was only temporary. Steroidal lysis did not appear to be related to chelation, since ethylenediaminetetraacetate did not cause lysis alone and antagonized some lytic compounds. Lecithin, Tween 80, Tween 20, and Span 20 at 0.05% exhibited certain effects on protoplast stability. Span 20 strongly prevented lysis by steroids. Tween 20 alone quickly caused protoplast rupture. Lecithin and Tween 80, which also caused lysis alone, interfered with lytic steroids and CPC. The test compounds were both inhibitory and lethal to cells of Sarcina lutea. The results suggest that direct action on cell membranes may be chiefly responsible for the antimicrobial properties of the steroids.