Bar Soap Containing Water-soluble Phosphate Polymers for Controlled Release of Antimicrobial Silver and Other Bioactive Metal Ions

The antimicrobial properties of silver ions have been known since ancient times, and several studies have explored the mechanisms of action that make them effective against such a broad range of microorganisms.1 This includes Gram-positive and Gram-negative bacteria,2, 3 fungi and yeasts,3 and viruses.4–6 Silver ions work in a number of ways, most noticeably by disrupting essential cell transport, i.e., the movement of nutrients, metabolites and waste in, out and around the cell; protein synthesis;7 and reproduction by interfering with the microorganism’s DNA and RNA.8, 9 This effectively starves or suffocates the microorganism, preventing its replication and resulting in inert stasis or death.

However, some microorganisms have a greater tolerance of silver than others, and even show a degree of resistance. Silver ions are non-selective and as noted, affect the performance of a number of critical physical functions within microorganisms. Therefore, in order to become resistant to silver ions, an untreated microorganism would need to mutate several critical functions simultaneously in a single generation through spontaneous mutation. The likelihood of this is very low;10–13 to date, the emergence of any silver-sensitive pathogen made resistant from the clinical use of silver has not been reported.

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