COMPARISON OF ANTIMICROBIAL EFFICACY OF SILVER-CONTAINING AND NON-SILVER CONTAINING DRESSINGS AGAINST P. AERUGINOSA AND S. AUREUS IN VITRO Katie Bourdillon1, Kyle Turton1, Mathew Westmoreland1 1Systagenix (Gatwick, United Kingdom).

1. Abstract
Background
Objectives and Aims
Log10 reduction assay
Conclusions
Comparison of antimicrobial efficacy of silver‐
containing and non‐silver containing dressings
against P. aeruginosa and S. aureus in vitro
Katie Bourdillon, Matthew Westmoreland, Kyle Turton, Systagenix, Gargrave, UK
C1419
EP450 EWMA May 2013

2. 013
Abstract
mpregnated Activated Charcoal Dressings (SIAC) have been shown to reduce bioburden in
c wounds. However some reports have raised concerns over the efficacy of such products.
tly, alternative Antimicrobial Bacterial Binding dressings (ABB) have emerged which do not
n a recognized antimicrobial. This study compared the antimicrobial efficacy of SIAC* and
against clinically significant organisms S. aureus (SA) and P. aeruginosa (PA) in vitro.
timicrobial efficacies of the dressings were evaluated in triplicate using a log10 reduction
which exposes a small sample of dressing to a bacterial culture. Samples of culture were
ed over 3 hours and total viable counts (TVC) determined. The ABB was tested in standard 8
m and a 1 ply form to reflect varying application methods in vivo.
ressings were highly active against both bacterial strains tested, with an average of ≥5 log10
ion in PA and ≥4.6 log10 reduction in SA TVC observed within 3 hours. In contrast, the 8 ply
ad only a minor effect on TVC, with log10 reductions of ≤1.3 log10 units observed for both
ial strains tested. No significant reduction of TVC was seen for 1 ply ABB compared to
ls.
wo SIAC dressings showed high antimicrobial efficacy, particularly against PA where TVC were
ed significantly within 3 hours. In contrast the ABB dressing had only a minor impact on the

3. 013 AIMS AND OBJECTIVES
udy compared the antimicrobial efficacy of
ver impregnated activated charcoal
ng SIAC1* and SIAC2*, with the bacterial
g DACC‐based dressing ABB† against
lly significant organisms S. aureus and P.
nosa in vitro.
ntimicrobial efficacies of the dressings were
ted using a log10 reduction assay which
es a sample of dressing to a bacterial
e. Samples were challenged with each
ia in triplicate and total viable counts
mined over a 3 hour period.
as tested in both the 8‐ply format it is
ed in and an unfolded 1‐ply format to
varying application methods in vivo.
SIAC1

4. 013
Log10 reduction assay: Measure of
antimicrobial efficacy
Inc. 0 – 180mins
370C 150rpm
Inc. 24 hours
370C
Water bath
10ml bacterial
solutionTest sample
Dilute sample and plate onto
agar
Count colonies
 Test dressings were cut to size (2.5 x 2.5cm) and placed in 10ml of bacterial
suspension with a starting concentration of 106 CFU/ml.
 Suspensions with no dressing added were included as controls.
 Dressings and suspensions/controls were shaken for 30 mins after which a
sample was removed and the bacterial concentration calculated.
 This process was repeated at addi onal me points –60 and 180 minutes

5. 013
microbial Results: Log10 reduction of S. aureus ATCC 6538 after exposure to various
commercially available dressing samples in Vitro
IAC1 and SIAC2 were
active against S. aureus,
a 4.6 and 5.2 log10
on in total viable counts
three hours observed
ively.
ntrast, no significant
nce was seen in total
count after exposure to
either format, with log10
ons of ≤0.3 log10 units
ed.
‐1,00
0,00
1,00
2,00
3,00
4,00
5,00
6,00
0 0,5 1 1,5 2 2,5 3
Log10 reduction
Time (h)
Control SIAC 2 SIAC 1 ABB 1 ply ABB 8 ply

6. 013
microbial Results: Log10 reduction of P. aeruginosa ATCC 27318 after exposure to
various commercially available dressing samples in Vitro
SIAC dressings were
strated as being highly
against P. aeruginosa.
reduced bacterial total
counts by 5.5 log10 units
1 hour; with SIAC2 a 4.6
eduction was observed
3 hours.
ntrast, only a minor
nce was seen in total
count after exposure to
either format, with log10
ons of ≤1.3 log10 units
ed.
‐1,00
0,00
1,00
2,00
3,00
4,00
5,00
6,00
0 0,5 1 1,5 2 2,5 3
Log10 reduction
Time (h)
Control SIAC 2 SIAC 1 ABB 1 ply ABB 8 ply

7. 013
CONCLUSIONS
Both SIAC1 and SIAC2 showed high antimicrobial efficacy against the
organisms tested. It is of note that SIAC1 was particularly effective against P.
aeruginosa where total viable counts were reduced by >5 log10 units within
1 hour.
These results are consistent with previous data which found SIAC dressings
to be effective at reducing bioburden and infection in both in vitro and in
vivo studies6,7,8
In contrast ABB had only a minor impact on the total viable counts of either
bacteria tested, despite being marketed as an antimicrobial dressing.
These results should be considered when determining the appropriate
dressing to use in the clinical setting to assist in the treatment of infected
wounds.

8. 013
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