The Science of Antimicrobial Silver: From Hieroglyphs to HAIs

By Jeffrey A. Trogolo, PhD

Although it is one of the most potent antimicrobials available, silver, in particular ionic silver, is safe. A naturally occurring element, silver has long been used as an antimicrobial; as early as 79 AD in Egypt it was used in long-term water storage, and in the 900s, Chinese emperors would only use silver eating utensils "to prevent poisoning." In more recent history, in the 1920s, more than 3 million prescriptions were written annually for silver-containing medications, and in the 1960s, silver compounds began to be used in burn wards. In the 1970s, silver-based applications reemerged; in the 1990s commercialization of silver antimicrobials for plastics and coatings began, and in the 2000s, there has been broad use of silver in medical devices and facility hardware.

How does it work? In the case of Agions silver-based antimicrobial technology, a zeolite carrier provides many benefits over other antimicrobials that are alcohol-, chlorine-, or ammonium-based. Agion technology operates at the surface of a product through the controlled release of silver ions, which attack microbes and inhibit their growth, preventing multiple targets in the microbe from growing to a destructive population. This tri-modal action fights cell growth in three ways: prevents respiration by inhibiting transport functions in the cell wall; inhibits cell division ; and disrupts cell metabolism.

As healthcare-acquired infections (HAIs) become a critical issue for hospitals across the globe, a growing number of medical device manufacturers have developed products that feature silver-based antimicrobials everything from urinary catheters to reduce the risk of urinary tract infections to endotracheal tubes to ward off ventilator-associated pneumonia. From the manufacturers perspective, antimicrobial-treated devices provide a competitive edge in todays challenging healthcare marketplace.

That brings us to the fact that not all antimicrobials are created equal. Manufacturers certainly dont want to use therapeutic antibiotics to treat medical devices since antibiotics can contribute to resistant organisms and will not be effective against them. Second, safety is a primary concern since the antimicrobial will be released onto or into the patients body over a period of time. Third, the antimicrobial must be effective against a broad range of organisms. Fourth, it must be durable enough to be processed into the device material.

There is one antimicrobial that embodies all of these properties ionic silver. The end goal: to maintain clean surfaces 24/7, via an integrated infection control strategy that includes carefully timed, thorough cleaning procedures, personal care practices among facility personnel, and equipment choices that boost these efforts. It is as part of the latter element that silver plays an important role. When added to control colonization on the surface of a device, whether that device is high-touch healthcare facility hardware door knobs, bed rails, light switches, etc. or as previously stated, medical devices, antimicrobial silver is a vital component of an overall HAI prevention strategy.

Jeffrey A. Trogolo, PhD, chief technology officer and director of Agion's technology operations and product development, was an original member of the team that founded Agion Technologies. This work has earned him the 2006 Technology Pioneers Award from the World Economic Forum.