The Use and Efficacy of Silver Dressings
Introduction
Historical Use of Silver
The use of silver as a prophylactic treatment dates back to about 1000 BC, when the ancient Greeks and Romans
used it as a disinfectant, placing silver coins in jars of water and other liquids to sterilize the liquids.1,2 Early in the 19th
Century the antimicrobial activity of the silver ion was identified,2 and in 1920’s the US Food and Drug Administration
accepted colloidal silver as being effective for wound management.2,3
Over the past 25 years, the medical and scientific communities have developed a body of research which
demonstrates the safety and efficacy of silver as a therapeutic tool.3,4,5 Some basic mechanisms of action which have
been identified through scientific research are:
•Degrade bacterial enzymes by stimulating K+ ion release.
•Cell wall degradation.
•Inhibit cell mitotic activity.
•Increase stimulation of bacterial cytoplasmic abnormalities.
•Interact with DNA bases.6,7
Measurement of Antibacterial Activity
Silver is currently one of the more popular topical antiseptic agents that has been incorporated into dressings.
There is little doubt as to the antibacterial properties of silver, but clinical trials have utilized varying organisms and
methodologies which has led to difficulty in interpreting comparisons between dressings. The levels of silver ions
released by dressings in vitro have been measured and presented in several ways, including:
•Parts per million: Expression of silver concentration as parts per million (ppm) has been used and 5-50 parts
of silver per million is toxic to most bacteria.8 For example, TRIACT with Silver releases 50 - 120ppm.
•Log reduction: Many studies have used a log10 reduction in bacteria to assess microbicidal activity.
A 103 reduction is considered microbicidal.9,10
Silver dressings are bactericidal and fungicidal, and can be effective against resistant organisms or known pathogens
such as MRSA and Pseudomonas.8,11,12,13
Conclusion
Thus far, research on the antimicrobial efficacy of silver has been limited to in vitro studies, and despite the data on the
microbicidal properties of silver, some debate exists as to the effectiveness of silver dressings in wound healing.
Ultimately, the use of silver dressings in affecting positive outcomes in wound healing is best evaluated through clinical
use of the dressings. Although there are very few controlled randomized clinical trials in vivo, a recent study compared
the efficacy of a silver contact layer with the same dressing in a non-silver formulation. After 8 weeks, the wounds
covered with the silver dressing exhibited better wound closure (P = 0.002) than the wounds covered with the control
(non-silver) dressing.14
Advantages of Silver Dressings
Silver dressings from Hollister Wound Care offer many advantages, including:
•Effective: In vitro studies show sustained silver release that is effective against bacteria most frequently associated
with wound infections, including MRSA, Streptoccus pyogenes and Pseudomonas aeruginosa. This antimicrobial
activity is sustained for the full duration of the dressings’ wear-time (see Instructions for Use).
•Versatile: Available in a variety of dressings for managing a wide array of wounds
•Simple: The dressings do not need to be activated with saline or H20. The silver in Restore dressings is
released from contact with wound exudate.
Contents
n Triact Technology with Silver: Description and general characteristics . ....................... 2-3
n The silver ion: Antibacterial mechanism of action . ............................................................. 4-5
n Products featuring TRIACT Technology with Silver ............................................................... 6-7
n In vitro studies on the antibacterial efficacy of the TRIACT with Silver interface .................. 8-9
n RESTORE Calcium Alginate dressing with Silver ............................................................ 10
n In Vitro studies on the antibacterial efficacy of Restore Calcium Alginate Silver dressing ...... 11
n Frequently Asked Questions .............................................................................................. 12
n References ......................................................................................................................... IBC
1
Triact
Technology
Description and general characteristics
Composition and properties
Restore Contact Layer, Silver is a sterile
non-adhesive, non-occlusive, antimicrobial
wound contact dressing, composed of a
polyester mesh with a matrix comprised of
hydrocolloid particles (carboxymethylcellulose),
cohesion polymers, petrolatum and silver
(2.25mg/sq.inch).
Structure of the dressing mesh
The TRIACT mesh is a 100% polyester textile,
non-deformable, continuous yarn, coated with the
TRIACT with Silver matrix. The non-deformable nature
of the mesh and its constantly open pores help avoid
maceration and allows exudate to pass through into the
outer absorbent layers without sticking.
The locked net structure of the mesh provides a
continuous multifilament, reducing potential
for microfiber shed in the wound. Flexible filaments
allow the dressing to conform to a variety
of wound types and body contours.
2
with Silver:
Mechanism of action
When in contact with exudate, a gel is formed, providing a moist environment that promotes healing. In addition,
the silver ion is released from the silver sulfate molecule. This is ionic (Ag+) silver. The dressing sustains
antibacterial activity for up to 7 days in in vitro studies.
The dressing is non-adhesive, so removal is virtually pain-free and helps minimize damage to newly formed
surrounding skin. It is ideal for use on wounds with fragile periwound skin. Dressing changes are recommended
every 1 to 3 days, depending on the wound and the healing progression.
Shown to be effective (at least 4 log reduction) against bacteria
associated with wound infections including:
• Streptococcus pyogenes
• Pseudomonas aeruginosa
• MRSA
Microscopic view of the
CMC material surrounding
the TRIACT matrix
3
The silver ion:
Antibacterial mechanism of action
The silver ion
Ionized silver (Ag+ cation) is one of the most potent antibacterial agents, active at extremely low concentrations
(between 0.0000001% and 0.00006%).16,17
This rapid and bactericidal antimicrobial activity at very low concentrations (1.5 μg/ml) is the consequence of a
“multi-target” mechanism of action on numerous bacterial sites, thereby minimizing any risk of selection of resistant
mutant microorganisms.
Silver sulfate
Formula
• Silver sulfate is a silver complex.
• Structural formula: Ag2SO4.
• Silver sulfate is a white, amorphous salt presented
in the form of a powder.
• It is not very soluble in water (less than 5.7 g/l).
Release of the silver ion
and antibacterial activity
• Silver sulfate compound is not very soluble and
cannot cross the cell membranes and exert any
antibacterial activity.
The antibacterial activity only happens following breakdown of the silver salt in contact with the wound exudate (as shown in the diagrams on
opposite page).
• The Ag+ ion quickly reacts with the bacterial DNA, replacing the hydrogen atoms linking the two nitrogens belonging to two bases that face each other on the molecule chains of the bacterium’s DNA (as shown in the diagrams on this page).16,17
This substitution by silver blocks bacterial duplication and replication.
The bacterium is then incapable of reproducing and the synthesis of proteins is blocked.
4
Mechanism of action
• In contact with the wound exudate, the
silver sulfate breaks down (Ag2S04→2 Ag+
+ S042-) and releases the Ag+ ion, while the
Carboxymethylcellulose particles become
hydrated and swell to form a surface
hydrocolloidal gel.
• Dissolved in this way, the silver ions are in an
ionic form that is the source of their
antibacterial activity.
TRIACT polymer matrix
Unlike many other silver dressings, dressings
featuring TRIACT with Silver do not require
hydrating with water or saline prior to use, nor
are they inactivated by water or saline.
The release of Ag+ from the silver sulfate and
its bioavailability at the surface of the dressing
interface occurs upon contact with exudate.
In contact with wound
exudate, the CMC
particles swell, break
free of the polymer
matrix, and form a gel.
At the same time, silver
ions are also released
in the dressing.
Ag +
Ag +
Ag +
Ag +
Ag +
Ag +
CMC
Ag +
Ag2 SO4
Ag +
Ag +
Ag +
Ag +
Ag +
Ag +
Ag +
Ag +
Ag +
Ag +
4818-Illustrations-Chimie2-10
5
Products
featuring TRIACT Technology with Silver
RESTORE Contact Layer, Silver with TRIACT Technology
Non-Adherent Dressing, Antimicrobial
n Description
Restore Contact Layer, Silver is a non-adhesive, non-occlusive, antimicrobial wound contact dressing,
composed of a non-occlusive polyester mesh with a polymer matrix containing hydrocolloid particles
(carboxymethylcellulose), petrolatum and silver (2.25mg/sq.inch). Method of sterilization: Sterilized
by ionizing radiation.
n Indications For Use
The barrier functions of Restore Contact Layer, Silver may help reduce infection in low to moderate exuding
partial and full thickness wounds, including second degree burns, pressure ulcers, venous stasis ulcers, diabetic
ulcers, and graft and donor sites.
TRIACT Technology
• Petrolatum particles
• Hydrocolloid particles
• Silver sulfate
6
RESTORE Foam Dressing, Silver with TRIACT Technology
Antimicrobial, Non-Adhesive with Non-Adherent Contact Layer
n Description
Restore Foam Dressing, Silver Non-Adhesive is a non-adhesive, non-occlusive, antimicrobial absorbent
dressing, composed of 3 layers:
• In contact with the wound, a non-occlusive polyester mesh with a polymer matrix containing hydrocolloid
particles (carboxymethylcellulose), petrolatum and silver sulfate (3.22mg/sq.inch).
• A non sensitizing, absorbent polyurethane foam pad.
• A protective, semi-permeable polyurethane backing.
• The mesh size allows the exudates to drain into the absorbent foam pad, reducing the risk of maceration.
• The TRIACT mesh allows virtually pain-free removal of the dressing and minimizes damage to newly
formed tissue.
n Indications For Use
The barrier functions of Restore Foam Dressing, Silver Non-Adhesive may help reduce infection in
moderately to high exuding partial and full thickness wounds, including partial thickness burns, pressure ulcers,
venous stasis ulcers, diabetic ulcers, and graft and donor
sites. May be used under compression bandages.
TRIACT Technology
• Petrolatum particles
• Hydrocolloid particles
• Silver sulfate
super-absorbent Layer
Vertical absorption of exudate
semi-permeable backing
Helps protect the surrounding skin from
maceration and allows for favorable MVTR
n In contact with the wound
The TRIACT with Silver interface releases the silver ion in the dressing and directs the exudate through its
mesh towards the absorbent foam (flow conduction). The super-absorbent foam is an expanded polyurethane
foam with a honeycomb structure that provides high-performance absorption (4300 g / m2 / 24 h) and exudate
retention (≤ 50 %) profile under pressure. The semi-permeable backing at the surface enables vaporization of any
excess exudate in order to reduce the risk of dressing saturation and maceration to the wound or periwound skin.
7
In vitro studies on the antibacterial
efficacy of the TRIACT with Silver interface
Introduction
The antibacterial activity of the Ag+ ion has
been known since the studies conducted by
Billroth in 1874, who first demonstrated its
antibacterial properties. Since then, numerous
studies have validated its ­antibacterial efficacy
on the ­microorganisms most commonly
involved in the s­ econdary ­infection of
wounds. The emergence of strains that are
­multiresistant to antibiotics, ­initially c
­ ontained
­within hospital settings but ­increasingly ­often
found in community ­medicine, means that it
is necessary to perform ­studies on its activity
against these microorganisms.
Objective
To determine the antibacterial properties of
the TRIACT with Silver (Restore Contact Layer,
Silver) on the survival of reference ­bacteria
colonizing acute and chronic wounds, along
with strains resistant to antibiotics, including
Methicillin-Resistant Staphylococcus aureus
(MRSA).
Method
Determine the survival curves of the ­different
micro­organisms relative to the population
­observed with a control dressing without silver.
The ­samples of dressing are inoculated with
a bacterial ­suspension of 108 CFU (colonyforming units) and incubated. The number of
surviving bacteria is calculated daily up until D7.
8
Results
Control
Control
RESTORE Contact Layer,
RESTORE Contact Layer,
Silver
Silver
10
9
109
Conclusion: Study of the bacterial survival curves reveals
the antimicrobial activity of the TRIACT with Silver interface
in comparison with the same dressing without silver.
From D1 and throughout the duration of the ­study, the
reduction in the number of CFU for all the bacterial strains
studied is greater than 104, making it possible to conclude that
the TRIACT with Silver ­interface demonstrates antibacterial
efficacy on the ­microorganisms tested.
108
108
107107
106106
105105
104104
103103
102102
101101
0 0
D2 D3
D3 D4
D4
D7
D0D0 D1D1 D2
D7
Methicillin-resistant Staphilococcus aureus
Survival curve (MRSA) (ATCC43300)
TRIACT with Silver has shown the following log reductions for
these bacteria (the log reduction is achieved within 24 hours
and is maintained for a seven day period):
1011
Name of BacteriaLog Reduction
1010
Methicillin resistant staphylococcus aureus
Pseudomonas aeruginosa
Streptococcus pyogenes
10
Témoin
Interface TLC Ag
9
108
107
106
105
104
103
102
Témoin
101
0
D0
D1
D2
Interface TLC Ag
D3
D5
D7
Pseudomonas aeruginosa Survival curve (ATCC902)
Data on file
108
107
106
105
104
103
102
101
0
D0
D1
D2
D3
D7
Streptococcus pyogenes Survival curve (ATCC 19615)
9
8 (108)
4 (104)
7 (107)
Restore Calcium Alginate Dressing, Silver
n Description
Restore Calcium Alginate Dressing, Silver is a sterile, non woven pad composed of a
high G (guluronic acid) calcium alginate, carboxymethylcellulose (CMC) and ionic silver
complex (Silver Sodium Hydrogen Zirconium Phosphate).
Restore Calcium Alginate Dressing, Silver features superior absorbency and wet
strength, which provides several key benefits:
• Remains intact even when saturated – allows easy, one-piece dressing removal
• Less residue than other dressings – reduces the need for repeated irrigation that
might damage new tissue
• Absorbs exudate - protects the peri-wound skin while maintaining a moist wound environment
n Indications For Use
Restore Calcium Alginate Dressing, Silver is indicated for moderate to heavily exuding partial to full
thickness wounds including venous stasis ulcers, arterial ulcers, pressure ulcers, diabetic ulcers, trauma
wounds, post-operative wounds, and graft and donor sites.
n In contact with the wound
RESTORE Calcium Alginate Dressing,
Silver is more absorbent than the
leading alginate dressing.
High Wet Strength
28
Absorbency (g/100cm2)
In the presence of wound exudate, the dressing releases
silver ions. As wound fluid is absorbed the alginate forms
a gel, which assists in maintaining a moist environment
for optimal wound healing, and allows for intact removal.
The silver ions released in the presence of wound exudate
in the dressing are an effective antimicrobial agent
against a broad spectrum of micro-organisms frequently
associated with the bacterial colonization and infection
of wounds. Odor reduction results from the antibacterial
effect in the dressing. Restore Calcium Alginate Dressing,
Silver is an effective barrier to bacterial penetration.
29
24
20
20
16
12
8
4
0
RESTORE
Silver Alginate
Aquacel Ag
RESTORE Calcium Alginate Dressing, Silver
has sustained silver release.
Silver Release (ppm)
v Aquacel Ag
v RESTORE Silver Alginate
200
100
0
2
RESTORE
4
12
24
48
Time (Hours)
Competitor
10
96
168
In Vitro studies on the
antibacterial efficacy of Restore
Calcium Alginate Dressing, Silver
107
106
105
104
103
102
Objective
To determine the antibacterial
properties of Restore Calcium
Alginate Dressing, Silver on the
survival of reference bacteria
commonly colonizing acute
and chronic wounds, including
strains resistant to antibiotics
(MRSA, MRSE, and VRE).
Test Method
Determine the survival curves
of the different micro-organisms
relative to the population
observed with a control dressing
(calcium alginate without silver).
The dressings are inoculated
with the micro-organism (106
CFU), incubated,then the
number of surviving bacteria is
calculated at defined intervals.
Conclusion:
Study of the bacterial survival
curves shows the antimicrobial
activity of the Restore Calcium
Alginate Dressing, Silver in
comparison with the calcium
alginate dressing without silver
(control).
From D1 through D7, the
reduction in the number of
CFU for all the bacterial strains
studied is greater than 105,
making it possible to conclude
that the Restore Calcium
Alginate Dressing, Silver
demonstrates antibacterial
efficacy on the microorganisms
tested.
Data on file, Report No. P1081R
Results
Control
Control
RESTORE Calcium Alginate
Dressing,
SilverAlginate
RESTORE
Calcium
Dressing, Silver
109
101
0
D0
D1
D2
D3
Candida albicans Survival curve
10
108
10
107
10
106
108 7
107 6
106
105 5
105
10
4
104
10
3
103
102
102
102
101
10
1
101
00
0
104
103
D7
109
109 8
10
D4
D0 D1
D1 D2D2 D3D3 D4D4 D7 D7
D0
Methicillin-resistant Staphilococcus aureus
Survival curve (MRSA)
D0
D1
D2
D3
D4
Streptococcus pyogenes Survival curve
109
109
10
8
108
107
107
106
106
10
105
4
10
104
103
103
10
102
1
10
101
0
0
5
2
D0
D1
D2
D3
D4
D7
Methicillin-resistant Staphilococcus epidermis
Survival curve (MRSA)
D0
D1
D2
D3
Escherichia Coli Survival curve
109
109
108
108
107
107
6
10
106
105
105
104
104
3
10
103
102
102
101
101
0
0
D0
D1
D2
D3
D4
D7
Vancomycin Resistant Enterococcus Survival curve
(VRE)
11
D4
D7
D7
D0
D1
D2
D3
D4
D7
Psuedomonas aeruginosa Survival curve
Frequently Asked Questions
Is the use of dressings with silver sulfate an issue with sulpha allergies?
Some people are allergic to a family of drugs called the sulfonamides, or sulfa drugs. These are completely
different from the silver sulfate molecule found in Restore Contact Layer Dressing, Silver and Restore Foam
Dressing, Silver Non-Adhesive. Sulfate has nothing to do with the sulfonamide molecule, other than the two
names sound somewhat similar.
What type of silver is silver sulfate?
Silver sulfate is a salt. Its chemical formula is Ag2SO.4 The antibacterial activity only happens following
breakdown of the silver salt in contact with wound exudate. Once in contact with wound exudate, the silver
breaks away from the sulfate in the form of a silver ion (Ag+).
Why does the IFU reference changing silver dressings every 3-4 days
when the dressings have sustained silver release for up to seven days?
Common practice seems to be that wounds showing signs of increased bacterial burden are reassessed more
frequently than once per week.
How does silver affect bacteria?
Ionic Silver (Ag+) can affect bacteria in a number of ways:
• The silver ion (Ag+) alters the bacterial cell membrane structures, leading to a loss of the cell contents
• The silver ion (Ag+) disrupts the function of the intracellular enzyme systems and alters bacterial respiration
and nutritional metabolism of the bacterium
• The silver ion (Ag+) binds to the base of the bacterial DNA chains and blocks DNA replication 6,7
What is the PPM (parts per million) of silver that is effective?
Research suggests that 5-50 PPM of Silver is toxic to most bacteria.15
What is the difference between bactericidal and bacteriostatic,
and why is this important?
All Restore dressings with silver deliver bactericidal levels of silver, meaning they kill the bacteria. The term
bacteriostatic refers to the inhibition of growth and reproduction of bacteria. According to many wound articles
and experts, “In antimicrobial activity testing, an active such as silver may be considered bactericidal if it
achieves log10 reductions of 3 log10 or greater”.15
12
REFERENCES:
1 Demling RH, Effects of Silver on Wound Management. Wounds. 13(1-Suppl A): 5-15,2001.
2 Hugo W, Russell A., Principles and practice of disinfection, preservation and sterilization. Oxford UK: Blackwell Scientific Publications,
1982; 8-106.
3 Chopra I., The increasing use of silver-based products as antimicrobial agents: a useful development or a cause for concern?
Journal of Antimicrobial Chemotherapy 2007, 59: 587 – 590.
4 Lansdown A, Sampson B, Laupattarakasem P, Vuttivirojana A. Silver aids healing in the sterile skin wound: experimental studies in the laboratory
rat. British Journal of Dermatology. 137(5):728-735, November 1997.
5 Gamelli R. et al., A Silver-Coated Antimicrobial Barrier Dressing Used Postoperatively on Meshed Autografts: A Dressing Comparison Study.
Journal of Burn Care & Research. 28(5):715-719, September/October 2007.
6. Burd A, et al., A comparative study of the cytotoxicity of silver-based dressings in monolayer cell, tissue explant, and animal models.
Wound Repair & Regeneration. 15(1):94-104, January/February 2007.
7. Jung, WK, et al., Antibacterial Activity and Mechanism of Action of the Silver Ion in Staphylococcus aureus and Escherichia coli. Applied and
Environmental Microbilogy, Vol 74.(7). April 2008.
8. Yin HQ, Langford R, Burrell RE. Comparative evaluation of the antimicrobial activity of Acticoat antimicrobial barrier dressing. J Burn Care
Rehabil 1999;20:195-200.
9 Thomas S, McCubbin P. A comparison of the antimicrobial effects of four silver-containing dressings on three organisms. J Wound Care
2003;12:101-7.
10 Thomas S, McCubbin P. An in vitro analysis of the antimicrobial properties of 10 silver-containing dressings. J Wound Care 2003;12:305-8.
11 Lansdown AB Silver I.: its antibacterial properties and mechanisms of action. Silver 2: toxicity in mammals and how its products aid wound repair.
J Wound Care 2002;11:125-130 and 173-177.
12 Wright B, Lam K, Hansen D, Burrell R. Wound management in an era of increasing bacterial antibiotic resistance; a role for topical silver treatment.
American Journal of Infection Control; 26(6), December 2998, 572-577.
13 Russell A, Hugo W. Antimicrobial activity and action of silver. Prog Med Chem. 1994; 31:351-357.
14 Lazareth I, Meaume S, Sigal-Grinberg MI, Combemale P, Le Guyadec T, Zagnoli A, Perrot J, Sauvadet A, Bohbot S. The role of a silver releasing
Lipido-colloid contact layer in venous leg ulcers presenting inflammatory signs suggesting heavy bacterial colonization: results of a randomized
controlled study. Wounds 2008;20: 158-166.
15. Leaper D. Silver dressings: their role in wound management. International Wound Journal: (3)4:282 – 294.
16. Davies CE, et al, Use of 165 ribosomal DNA PCR and denaturing gradient gel electrophoreses for analysis of the microfloras of healing and non
healing chronic venous leg ulcers. J Clin Microbiol, 2004. 42(8):p. 3549-57.
17. Ovington LG, The truth about silver. Ostomy and Wound Mgmt, 2004, 50(9A Suppl): p. 1S-10S.
Manufactured for
Hollister Wound Care LLC
1580 South Milwaukee Avenue
Suite 405
Libertyville, IL 60048
1.888.740.8999
Distributed in Canada by
Hollister Limited
95 Mary Street
Aurora, Ontario L4G 1G3
1.800.263.7400
www.hollisterwoundcare.com
Hollisterwoundcare and wave logo are trademarks of Hollister Incorporated. Restore, TRIACT and graphic are trademarks of
Hollister Wound Care LLC. Covered under one or more of the following patents: U.S. Patent No. 6,270,792, 6,794,555 and 6,080,420.
Made and printed in USA. ©2009 Hollister Wound Care LLC. 910299-808
910678-409