Tackling infections with nanocrystalline silver
Reconstructive Solutions Nanocrystalline silver dressings kill bacteria, and carry less risk of resistance development than antibiotics. When are they best used?
“Silver is one of the main topical antimicrobial treatments for wounds, and especially burns. It is a powerful antibacterial and could play a significant role in tackling antibiotic resistance,” says Dr Chris Roberts, microbiologist and principal consultant at wound care consultancy Clinical Resolutions.
"Silver is not just valuable as a precious metal."
The Romans used silver coins to disinfect water, and in the 1940s wounds were packed with silver foil and even wire. Today it is widely used in general and reconstructive surgery.
Silver is particularly valuable in treating burns, which are especially susceptible to infection because the skin barrier is widely disrupted and the resultant wounds exude fluid on which bacteria thrive. In deeper burns, blood vessels die so they are unable to deliver infection-fighting cells to the burn area, and severe burns can result in immuno-suppression, so the patient is less able to fight infection.
Silver outperforms antibiotics in fighting bacteria
Roberts explains: “Silver kills bacteria by punching holes in their cell walls, disrupting their respiration and destroying their DNA. This triple-action makes silver a better bacteria fighter than antibiotics. After the discovery of antibiotics, antimicrobials such as silver fell from favour.”
However, by the mid-1960s, antibiotic resistance led to the re-use of silver, in the form of silver nitrate, as a burn treatment. However, because wound exudate neutralises silver's anti-bacterial effect, it had to be reapplied up to 15 times daily.
The introduction of silver sulfadiazine cream in the 1970s reduced dressing changes to around twice daily, and it is still used today.
"Nanocrystalline silver dressings only need to be changed every three to seven days."
The next breakthrough was the introduction of nanocrystalline silver in 1997. This progress allowed the new, unique coating on dressings to be in direct contact with the wound. “The molecular structure of nanocrystalline silver boosts its bacteria-killing action, which in turn extends the gap between dressing changes to three to seven days,” says Roberts.
Using silver today
However, in some burns units it is considered too expensive, and there are other, less powerful (and cheaper) silver-based dressings available, which can make it confusing for health care staff to choose the right dressing.
The solution is to use nanocrystalline silver dressings when they are most appropriate, says Roberts. “That is when you have a patient at high risk of infection – immunosuppressed, elderly or a child – or when you have a high-risk wound, where there is an existing high bioburden or local infection.
"The solution is to use nanocrystalline silver dressings only when they are most appropriate."
“Healthcare staff should ask themselves if they need to use an antibiotic, or an antimicrobial, and if the latter, whether the situations outlined above apply.”
Where they do choose nanocrystalline silver, any use should be early on, he says. “The faster you can control infection, the faster the wound will heal or a skin graft will take.”
What is more, he adds: “There is no evidence that modern silver dressings in clinical use have problems with resistance, which antibiotics now do.”