In World War I, before the advent of antibiotics, silver compounds were used to prevent and treat infections. Silver compounds continue to be used in external preparations as antiseptics, including both silver nitrate and silver proteinate, which can be used in dilute solution as eyedrops to prevent conjunctivitis in newborn babies. Silver nitrate is also sometimes used in dermatology in solid stick form as a caustic ("lunar caustic") to treat certain skin conditions, such as corns and warts.
According to Atiyeh et al. (2007), "The gold standard in topical burn treatment is silver sulfadiazine (Ag-SD), a useful antibacterial agent for burn wound treatment". They do note, however, that silver-impregnated dressings do sometimes result in a slower healing process. Silver sulfadiazine cream (SSD Cream) replaced colloidal silver as the most common delivery system for using silver on the surface of burn wounds to control infection in the 1970s.
The US Food and Drug Administration has approved the use of a range of different silver-impregnated wound dressings.
Laboratory studies at the Biochemical Materials Research and Development Center of Jiaxing College, China, have shown silver-containing alginate fibres provide a sustained release of silver ions when in contact with wound exudates, and are “highly effective against bacteria”. A study administered by the Hull York Medical School found an antimicrobial barrier dressing containing silver provided “a highly effective and reliable barrier to the spread of MRSA into the wider hospital.
More recently, dressings incorporating nanocrystalline silver or activated silver-impregnated substances have become available, which deliver higher concentrations of the active silver ion. As of 2006, more "than 10 dressings containing pure silver" were available. In particular, silver is being used with alginate, a naturally occurring biopolymer derived from seaweed, in a range of products designed to prevent infections as part of wound management procedures, particularly applicable to burn victims.
Wound dressings containing silver are increasing in importance due to the increase of antibiotic-resistant bacteria, which has imposed clinical limits on the use of antibiotics. Chopra states topical silver is regaining popularity in the management of open wounds, “due largely to the spread of methicillin-resistant Staphylococcus aureus and the resultant reduction in first-line antibiotic prescribing”, and “[s]ome silver-based dressings appear to provide an effective alternative to antibiotics in the management of wound infection.” Silver has proven broad-spectrum antimicrobial activity that includes antibiotic-resistant bacteria, with minimal toxicity toward mammalian cells at low concentrations, and has a less likely tendency than antibiotics to induce resistance due to its activity at multiple bacterial target sites.
However, some sources still hold that the evidence for the effectiveness of silver-treated dressings is mixed, as the evidence is marred by the poor quality of the trials used to assess these products. A meta-analysis of 26 studies in 2007 by the Cochrane Collaboration found that most of these studies were small and of poor quality, and that generally these 26 studies indicated that the treatments did not promote wound healing or prevent wound infections. Some evidence suggested that silver sulfadiazine actually slowed healing.
Wound dressing containing ionic silver are capable of killing multidrug-resistant organisms
ConvaTec, a world-leading developer and marketer of innovative medical technologies for community and hospital care, announced in vitro study results showing that a wound dressing containing ionic silver is able to kill several strains of multidrug-resistant organisms (MDROs), commonly referred to as 'superbugs.' The study results were published in the August issue of the International Wound Journal.
In the in vitro study, four models designed to simulate stringent clinical conditions were used to investigate the antimicrobial efficacy of AQUACEL™ Ag dressing. The simulated wound fluid (SWF) model was used to measure sustained antimicrobial activity over time. The simulated colonized shallow wound (SCSW) model was designed to investigate the effect of dressing conformability on activity of AQUACEL™ Ag dressing. The simulated colonized wound surface (SCWS) model was used to investigate the antimicrobial activity of the AQUACEL™ Ag dressing against a variety of MDROs seeded into agar directly beneath the dressing. The biofilm model (poloxamer) was used to assess the antimicrobial activity of the AQUACEL™ Ag dressing when each of the MDROs was expressing a biofilm phenotype. Non-silver AQUACEL™ dressing was used as a control where appropriate.
Multidrug-resistant organisms tested included Acinetobacter baumannii, community-associated methicillin-resistant Staphylococcus aureus, and extended-spectrum beta-lactamase-producing bacteria. Clostridium difficile was also included because it demonstrates many of the characteristics seen in MDROs and has evidence of emerging resistance.
Throughout all test methods, AQUACEL™ Ag dressing was shown to have consistent antimicrobial activity against a variety of MDROs. The authors concluded that in vitro antimicrobial efficacy of AQUACEL™ Ag dressing against a variety of MDROs could indicate a potential clinical benefit to preventing or controlling endogenous wound infections where antibiotic options are limited and tolerated by biofilm phenotypes. They further concluded that it may also act as an antimicrobial barrier to prevent the spread of such pathogens into the wider community.