Membrane-active agents resistance

The antistaphylococcal activity of 4-n-alkylphenols increases with increasing alkyl chain length from 2 to 6 carbon atoms [95], As the length of the alkyl chain increases so the water solubility falls, the lipid solubility rises, and the molecules become more surface active [95]. Penetration into the lipid-rich interior of the cell membrane therefore appears to be an important step in the antimicrobial action of the alkylphenols. Fattened staphylococci with increased Hpid content display some resistance to the alkylphenols because the molecules are bound to the extra lipid and are thereby denied access to the membrane [95]. Conversely, lipid-depleted cells are more sensitive than normal cells to alkylphenols and other membrane-active agents [96]. 

Especially remarkable is the high activity of PCMC against lipophilic, enveloped viruses, such as Herpes, simplex, Hepatitis B or HIV viruses. As other phenolic membrane active agents also PCMC exhibits a weak effect only on naked viruses and resistant bacterial spores (e.g. bacillus spores). However, a fully virucidal effect is achievable by combining PCMC formulations with small concentrations of glutaraldehyde (2.5.). 

T. Sata, Properties of composite membranes formed from ion exchange membranes and conducting polymers. 4. Change in membrane resistance during electrodialysis in the presence of surface active agents, J. Phys. Chem., 1993, 97, 6920. 

Antibiotic-resistant bacteria cause life-threatening infections in hospitals and society in general. There is a vital requirement to develop new antimicrobial agents, but this task involves extensive scientific trials. This chapter reviewed broad-spectrum polymeric antimicrobials, which are not susceptible to current resistance, and mechanisms of bacteria to mimic the antimicrobial action of natural HDP, which exert their effect by permeabilising the bacterial cytoplasmic membrane. Most cationic antimicrobial polymers appear to work in a manner similar to membrane-active AMP, such as magainin. The design and synthesis of different polymers, such as methacrylate-based copolymers, PPE, polynorbornene by-products, amphiphilc arylamide polymers and large polymers, have been studied as biomimetic polymers in different applications. 

Permeability changes have been observed in reconstituted cell membranes following treatment with surface-active agents [52] producing a selective permeability for cations. Addition of surfactant lowered the initially high resistance by several decades. 

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