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Section V.

COMPARISON OF ANTI-MICROBIAL ACTIVITY OF 
CURRENT SILVER PRODUCTS 

There are currently three silver products used in burns. 

• -a 0.5% silver nitrate solution

• -a 1% silver sulfadiazine cream

• - a bilayer pure silver ion (and radical) delivery system

ACTICOAT.

The characteristics of each of the products are presented followed by a head to head comparison of the killing rate of the 3 products.

Following the anti-microbial data is a series of recent studies again comparing the properties of the standard silver products with the new pure silver delivery system (ACTICOAT)

The comparative data has been reported over the last 2 years and the abstracts are included in addition to the comparative data.

CONCLUSION: Silver released from the pure silver delivery system (ACTICOAT) kills microbes more rapidly and completely than either of the other silver products.

SILVER NITRATE

Silver nitrate is used as an antimicrobial agent on wounds in a 0.5% solution. The antimicrobial action is provided by the silver ion Ag+. The silver ion does not readily into tissues when typically applied as a salt since the silver is readily precipitated by chloride to form an insoluble salt which proces a dark discoloration. The silver ion is active against gram positive and gram negative organisms and fungi. Continuous exposure is required. Problems with its use besides the potential for producing hypochloremia is that it is light sensitive and requires special handling. In addition, if it's allowed to dry on the surface hyperpyrexia can occur. Also nitrate is caustic to tissues (Silver concentration is calculated to be 3200 mcg/ml) in a 0.5% AgNO3 solution.

SILVER SULFADIAZINE

Silver sulfadiazine is used as a 1% water soluble cream combining sulfadiazine with silver cation (Ag+). Both the silver and the sulfadiazine has antimicrobial properties. The compound is effective against gram positive gram negative organisms and fungi. However resistance is now reported with long term use for a number of gram negative species especially pseudomonas. 

Antimicrobial activity upon cream application is 12-24 hrs. Tissue penetration is limited to a few millimeters (or less). This agent has been reported to retard wound healing.

SILVER DELIVERY SYSTEM (ACTICOAT) 

As described, the silver nanocrystals are coated onto high density polyethylene mesh present on both sides of the product with a polyester core between the sheets to maintain the moisture needed for silver release. 

• The ACTICOAT when wet with sterile water, (not with solutions) produces a continual release of Ag+ for days and likely other silver radicals for days. 

• The delivery system readily molds to the wound producing wound occlusion as well as maintaining a wound surface moisture layer. 

• Current published data indicates that this product produces a rapid and complete killing of essentially all pathogens found on a wound. 

• The spectrum consists of gram positive bacteria including methicillin resistant e. aureus and vancomycin resistant entercoccus; gram negative organisms including pseudomonas and klebsiella species 

• The silver release is also effective against fungi including Candida and Aspergillus. 

• No bacterial resistance has been reported with continued use when wet 

• It is painless to apply when wet and remove (every 2-3 days) although the amount of silver released is considerably less than silver nitrate. Published data wound indicate it is a much more effective antimicrobial. 

• No local or systemic toxicity has been noted. 

• Decreased wound inflammation occurs when ACTICOAT is in place which appears to accelerate re-epithelialization.

COMPARISON OF ANTIMICROBIAL EFFECTS OF SILVER PRODUCTS FOR BURNS

The silver products described as well as another antibacterial cream (non-silver) Mafendine or sulfamylon,are compared as to the rate of microbial killing. The microbes tested are the most common pathogens noted in wounds.

Note: Both the rate and the percent of microbial killing is greater with the nanocrystalline silver release ACTICOAT compared to any of the other products tested. Again, the likely explanation is the fact that only Ag+ is released from the silver nitrate and sulfadiazine compound while a variety of silver radicals including Ag+ could be released with the contact of silver crystals and water.

(J Burn Care Rehabilitation 1999;20:195-200)