Preparing the Wound Bed – Debridement, Bacterial Balance, and ...

Recommendation 6
Assess the Wound for Bacterial Balance and
Infection
The presence of wound-associated bacteria alone does not
indicate infection or impaired wound healing. Indeed, some
authors have suggested that a small amount of a certain bacteria
species in a chronic wound facilitates healing. 29,30 In
clinical practice, assessing when a wound has moved from a
symbiotic bacterial load that does not cause tissue damage to
an increased bioburden causing impairment of wound healing
can be difficult. The following equation demonstrates
that although bacterial quantity and virulence are significant
in assessing a wound for infection, host factors are of overriding
importance.
Risk of wound infection 31 = Bacterial dose x virulence
Host resistance
Factors such as immunosuppression, diabetes, and medication
all can influence whether any bacteria present will
impair wound healing. Furthermore, these factors can act to
mask classical signs of infection such as erythema, increased
temperature, pain, and edema.
Swab technique is important to obtain meaningful
results. 32 The wound should be cleansed with saline or water
and all debris should be removed. The healthy appearing
granulation is swabbed in a zigzag pattern, gently rotating
the tip of the swab (swabs are only recommended if clinically
indicated). If the wound is relatively dry, the swab may be
moistened with the transport media prior to swabbing. A
semiquantitative swab is then inoculated on standard media
in the lab and streaked in four quadrants. Results will indicate
no growth to 1 to 4+ growth of an organism, depending
on the number of streaked quadrants that support bacterial
growth. These swabs are quick and inexpensive. The
semiquantitative swab correlates well to the gold standard
quantitative biopsy results, 33 but there is some loss of specificity.
Despite the fact this is the procedure of choice in
most centers, inadequate wound bed preparation will result
in an excess number of confusing, nonsignificant wound
surface colonies appearing on the agar plates in the lab. The
clinical assessment of wound bioburden and the choice and
route of antibacterial agents should be based on host and
wound factors in association with wound swab results.
The concepts of bacterial contamination, colonization,
critical colonization, and local and systemic infection lend
themselves to guidance with regard to when to use antimicrobial
agents in wound care (see Table 5).
Most wounds are contaminated and contain nonreplicat-
24 OstomyWound Management
ing organisms. Colonization occurs when organisms are
replicating but not causing host injury. Skin commensals
such as Staphylococcus epidermidis and Corynebacterium
species are the most common colonizers. Neither contaminated
nor colonized wounds show signs of infection, and
impairment of wound healing is unlikely. The concept of
critical colonization (increased bacterial burden) has recently
been introduced to describe wounds moving between the
spectrums of colonization (where the host is unaffected) and
local infection (in which host injury occurs). It has been
suggested that during critical colonization, subtle clinical
signs of infection such as increasing pain/tenderness, increasing
serous exudate and friable granulation tissue, or failure
to heal may be present prior to the classical signs of foul
odor, frank pus, surrounding erythema, increased temperature,
pain, and swelling associated with infection. 34 It is
important to emphasize that many people with chronic
wounds, in particular people with diabetes, have an
impaired host response. These patients may therefore exhibit
only subtle signs, or even have a complete absence of signs
of infection (ie, no elevation in temperature) when bacteria
are damaging the skin and delaying healing. 35 A semiquantitative
swab with 4+ growth of a significant pathogen or a
quantitative biopsy with ≥ 1.0 x 10 6 cfu/g (cfu = colony
forming unit) of tissue in the presence of nonhealing may be
an indication for systemic antibacterial therapy. Therefore,
host monitoring is a vital part of assessment, with factors
such as raised blood sugar levels in people with diabetes
often being a helpful indicator of local or systemic infection.
Recommendation 7
Cleanse Wounds with Normal Saline or Water. The
Use of Topical Antiseptics Should be Reserved for
Wounds that are Nonhealable or the Local Bacterial
Burden is a Greater Concern than the Stimulation
of Healing
Cleansing and irrigation are used to eliminate exudate
and surface debris from wounds. Not only does this process
facilitate healing, but it also decreases bacterial burden by
removing heavily contaminated surface slough and debris.
Saline or sterile water are agents of choice for most
wounds. Tap water should not be used for immunosuppressed
patients and the water source should be reliably
clean before advocating it as treatment in other chronic
wounds. 36
Rodeheaver 28 studied wound cleansers in vitro to assess
cellular toxicity. He concluded that nonionic agents are best,