Journal of Community Nursing - page 25

JCN
2013,Vol 27, No 4
25
WOUND CARE
C
ontamination of a wound
with organisms is inevitable
and clinicians should
recognise that no wound is truly
sterile (Bowler, 2002). Despite
this, the majority of wounds do
heal (Gilchrist and Reid, 1989).
However, in some cases wound
contamination can progress
to infection, which negatively
impacts on healing and may
pose a significant risk of systemic
disruption or life-threatening
sepsis unless adequately controlled.
Such infections also increase
healthcare expenditure, due to the
cost of treatment and the rise in
the number of patients needing
hospitalisation (Cook and Ousey,
2011).
The relationship between the
patient (the host) and the micro-
organisms present in the wound
(the wound bioburden) is dynamic
— it is dependent on the numbers
of bacteria present, the ability of the
organisms to instigate a negative
effect on the host (virulence), and
the ability of the host to mount
an effective defensive response
Assessment, management and
prevention of infected wounds
(Heggers et al, 1992; Mertz and
Ovington,1993 Rumbaugh et al,
1999; Bowler, 2002).
There is no universal definitive
volume of bioburden at which
an infection can be said to occur,
although a bacterial count of 10
5
colony-forming units per gram of
tissue is considered sufficient to
impede healing in most cases
(Robson, 1997; Heggers, 1998).
While some organisms have little
effect on the body — meaning that
high concentrations are required to
elicit changes in the local wound
environment or produce systemic
signs and symptoms — other
organisms, such as haemolytic
streptococci, are virulent, and can have
a marked detrimental effect, even at
low numbers (Robson et al,1990).
In addition, pathogens work
synergistically to develop an
environment within the wound
in which proliferation is more
likely to occur (Bowler, 2003).
From very low numbers of bacteria
(contamination), the absence
of adequate host defences will
enable bacteria to multiply
(colonisation) until they impact on
the wound healing process (critical
colonisation).
Eventually, if unchecked,
bacterial numbers will increase to
induce a state of localised infection
or widespread systemic infection.
Kingsley (2001) describes this
direct relationship between wound
bioburden and the signs of infection
as the wound infection continuum.
Biofilms
Biofilms are complex microbial
communities containing bacteria.
As the bacteria and microorganisms
in a wound multiply they eventually
become attached, synthesise and
secrete a protective matrix of sugars
and proteins (Wolcott et al, 2008).
Biofilms may comprise
single bacterial species, or more
commonly, multiple diverse
species, which continuously change
and adapt to the surrounding
conditions.
The protective matrix enhances
the tolerance of microorganisms
embedded in the matrix to the
immune system, antimicrobials
and environmental stresses,
making them difficult to eliminate
(Flemming et al, 2007). This may
account for many of the chronic
low-grade infections seen clinically
(Wolcott et al, 2008).
RISK FACTORS
In general terms, any pre-existing
condition that impairs the vascular
perfusion of the wound or reduces
the individual’s ability to mount
an effective immune response
will increase the likelihood of
infection (McIntosh, 2007; World
Union of Wound Healing Societies
[WUWHS], 2008).
The risk of infection in the
acute wound is increased by
contamination, the presence of
Martyn Butcher, Independent Tissue Viability and
Wound Care Consultant, Devon
For the patient, wound infection can lead to poor healing outcomes
and has the potential to result in life-threatening sepsis. For
healthcare services, additional expense can be incurred due to the
need for remedial treatment and extra clinician time. Poor wound
infection rates also attract negative publicity and damage the
public’s perception of care standards. This article examines the
essential roles played by prevention of infection, early diagnosis
and the initiation of effective management strategies.
KEYWORDS:
Wound bioburden
Antimicrobial dressings
Infection risk factors
Martyn Butcher
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