Term
Definition and comment
Abscess
A collection of pus ( containing live and dead neutrophils
and macrophages, bacteria, fibrin and inflammatory
mediators, opsonins and complement, and dead cells
killed by the infective process) which has accumulated in
a cavity formed by surrounding granulation tissue
following an infection (usually caused by bacteria,
particularly staphylococci or bacteroides, or parasites) or
foreign materials (e.g. splinters, bullet wounds, or
injecting needles). It is a defensive and localising reaction
of the tissue to prevent the spread of infectious materials
to other parts of the body.
The organisms or foreign materials kill the local cells,
resulting in the release of cytokines. The cytokines trigger
an inflammatory response, which draws large numbers of
white blood cells to the area and increases the regional
blood flow. The tension within the abscess can be high
and is the cause of associated pain which is relieved after
drainage or spontaneous bursting
The final structure of the abscess is an abscess wall of
granulation tissue which is formed by the adjacent healthy
cells to localise the pus and prevent infection of
neighboring structures. However, such encapsulation
tends to prevent immune cells or antibacterials from
reaching bacteria in the pus. Abscesses tend to point to
the surface and they should be drained surgically.
Antimicrobials have a limited role unless there is
associated spreading cellulitis or bacteraemia
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
Acknowledgements
Antimicrobials
Agents which can inhibit the growth of or kill microorganisms. These can be antibiotics (active against
bacteria and given systemically), anti-fungal agents
(active against fungi), antiviral agents (active against
viruses) or anti-parasitic agents (active against parasites).
There are also other broad spectrum antimicrobial agents
such as antiseptics, disinfectants, preservatives and
biocides (which are chemically derived but applied
topically)
Antiseptics
Chemical, broad-spectrum, antimicrobial agents applied
topically to skin or underlying tissues to prevent or control
infection or increasing bacterial colonisation by killing or
inhibiting pathogens
Argyria
A term that is often misused. This very rare condition
produces blue-grey discolouration of the skin and is
associated with long-term systemic exposure to silver
salts. Argyria differs from the reversible local
discolouration that may be associated with silver
dressings; argyria is irreversible and can affect the skin of
the entire body and the internal organs.
The presence of viable bacteria in the blood. MRSA
bacteramia is mandatorily reported in the UK
WICP, page 10
Antimicrobial agents which destroy (kill) micro-organisms,
such as antiseptics, antibiotics and disinfectants
AWCN
Bacteraemia
Bactericidal
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
Bacteristatic
Antimicrobial agents which inhibit the growth or
multiplication of micro-organisms
AWCN
Bioburden
The amount of contaminating micro-organisms present in
tissues or on open ulcers/wounds prior to cleansing.
Bioburden ranges from contamination (least) through to
colonisation and infection (highest)
AWCN
Biofilms
A layer of bacteria and/or other microorganisms on a solid
or semi-solid surface, tissue or skin ulcer bound together
in a bacterially-derived polysaccharide matrix (glycocalyx)
shielded against the immune system and antimicrobial
agents..
There appears to be a correlation between biofilms and
non-healing in chronic wounds.
Cellulitis
A diffuse, spreading, acute infection of the skin and/or
subcutaneous tissues characterized most commonly by
local heat, redness and pain. There can be systemic
signs of tachycardia, tachypnoea, pyrexia and raised
white count and sepsis
Mosby’s PDQ for
Wound Care (2009).
Mosby-Elsevier, St.
Louis, MO.
Colonisation
Establishment of a community of microorganisms or
ecosystem in a tissue or open ulcer healing by secondary
intention, without necessarily resulting in tissue invasion
or damage.
WICP, page 1
Contamination
The presence of microorganisms in a tissue or open
wound healing by secondary intention, neither increasing
WICP, page 1
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
in number or causing clinical complications of infection. It
is a sequel of colonisation and precedes infection in open
wounds
Crepitus
A crackling feeling or sound detected on palpation of
tissues that is due to gas within the tissues. It is not
necessarily related to gas gangrene (Clostridium
perfringens specific) as other infecting organisms can
form gas in tissues
Critical colonisation
A point at which microorgansims are increasing in
numbers in tissues or an open wound but not releasing
virulence factors (or toxins) to cause infection. It may be
related to delayed healing but is hard to define.
Chemical agents whicjh are directly toxic to cells,
preventing their reproduction or growth and causing cell
death. This includes disinfectants which do kill bacteria
but are also toxic to healthy tissues
The removal of necrotic or foreign material from and
around a wound to optimise wound healing. There are
many different methods that can be used to debride a
wound. They can be broadly classified as surgical/sharp,
mechanical, biological, enzymatic and autolytic.
Cytotoxic
Debridement
Sharp debridement is the removal of dead or necrotic
tissue or foreign material from and around a wound to
expose healthy tissue using a sterile scalpel, scissors or
both.
Mechanical debridement involves methods such as wetto-dry dressings, wound irrigation, and similar techniques
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
WICP, page 10
AWCN
David Leaper, World
Wide Wounds 2002,
plus Schultz,
Sibbald, Falanga et
al, WRR 2003;11:128
that physically remove debris from a wound.
Biological debridement broadly describes the application
of sterile larvae to the wound area.
Enzymatic debridement involves the topical application of
endogenous enzymes.
Autolytic debridement is a process that spontaneously
separates necrotic tissue and eschar from healthy tissue;
it occurs to some extent in all wounds.
Dehiscence
Delayed healing
Evidence supporting one method over another is lacking.
The separation of a surgical incision or sutured wound
exposing underlying tissues but not necessarily exposing
deep contents of a body cavity. Used in the past to
describe burst abdomen or chest where all layers of a
surgical wound separate with exposure of viscera It is a
surgical complication that results from poor wound
healing. Risk factors include infection, age, diabetes,
underlying disease such as cancer, obesity,
immunosuppression, poor suture or surgical technique.
Healing progresses at a slower rate than expected. As a
guide:
■ in open surgical wounds healing mainly by
epithelialisation, the epithelial margin advances at about
5mm per week
■ clean pressure ulcers with adequate blood supply and
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
IWII committee
WICP, page 10
innervation should show signs of healing within two to
four weeks
■ a reduction in venous leg ulcer surface area of >30%
during the first two weeks of treatment is predictive of
healing
A chronic wound might be defined as a failure to heal
after 6 weeks despite optimal conditions (such as
adequate debridement and dressings, pressure relief,
diabetic control, adequate arterial inflow or compression
in pressure, diabetic, arterial or venous ulcers)
Erythema
Redness or inflammation of the skin or mucous
membranes that is the result of dilation and congestion of
superficial capillaries. It can be caused by invasive
bacteria such as -haemolytic streptococci
Endotoxin
A toxin that forms an integral part of the cell wall of certain
bacteria (Gram negative rods in particular) and is only
released upon destruction of the bacterial cell.
Endotoxins are less potent and less specific than most
bacterial toxins but can cause pyrexia and sepsis.
Exotoxin
A toxin that is released from an actively growing cell, is
heat labile and often proteinaceous in nature. It has a
specific target and can be used to form toxoids which are
used in vaccines. Many are important virulence factors in
pathogenic bacteria e.g. Panton Valentine Leukocidin
(PVL) of Staphylococcus aureus which can cause a
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
Mosby’s PDQ for
Wound Care (2009).
Mosby-Elsevier, St.
Louis, MO.
necrotising cellulitis and pneumonia
Foreign body
Every foreign body has the potential to act as a nidus for
infection and to impair wound healing. The majority of
wound debris may be removed through meticulous,
copious irrigation. However, direct visualization and
removal with instruments may be required. Objects can
either be inert (nonreactive) or organic (reactive).
Examples of inert objects include bullets, needles, and
metal objects. While these may cause chronic pain, they
may not provoke an inflammatory response. Organic
materials—such as wood, bone, stone, rubber, and soil—
may cause infection and must be completely removed.
Their presence in tissues can logarithmically reduce the
numbers of organisms needed to cause an infection
Genotype
The genetic constitution (the genome) of a cell, an
individual or an organism. The genotype is distinct from
its expressed features, or phenotype. The genotype of a
person is her or his genetic makeup. It can pertain to all
genes or to a specific gene.
Gram stain
A method of differentiating bacterial species into two
groups, Gram- and Gram+, based on the chemical and
physical properties of their cell walls. Staphylococci and
streptococci are Gram positive cocci; E.coli and
pseudomonas are Gram negative rods
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
Atlas of Emergency
Medicine
Hypertrophic scar
An abnormal scar in which there is excess scar tissue
formed, especially across a joint surface. The reddened
scar tissue does not exceed the original size the wound.
Hypertrophic scars tend to regress spontaneously
Induration
Hardening and swelling of the skin and subcutaneous
tissues around a wound due to inflammation, which may
be secondary to infection. The oedema and “tumor” of
inflammation
Infection
Multiplication and invasion of an infectious agent within
the body tissues causing signs and symptoms of disease.
In wound care the most common are Gram positive cocci,
such as staphylococci; and Gram negative rods, such as
pseudomonas
Redness, warmth, swelling and pain (the Celsian rubor,
calor, tumor and dolor) and decreased function (the
mediaeval addition of function laesa) seen in injured,
infected or irritated tissues. Inflammation is also the first
mechanism used as a type of nonspecific immune
response. In wound care it usually pertains to infection
Inflammation
Invasion
The process whereby an infectious agent (in wound care
usually bacteria) enters the host
cells or tissues and spreads in the
body (as cellulitis, lymphangitis and
bacteraemia).
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
WICP, page 10
Keloid scar
Keloids represent excess scar formation that grows
beyond the borders of the original wound and does not
tend to resolve spontaneously. Keloids tend to form in
persons with darker skin pigmentation and can form as
late as a year after injury.
Lymphangitis
Inflammation of lymph vessels, seen as red skin streaks
running proximally from a site of infection. Most often
seen with streptococcal and staphylococcal infections
Micro-organism
Organisms that are microscopic or invisible to the naked
eye, including bacteria, fungi, viruses, and parasites
Multi-organ dysfunction
syndrome
MODS is the presence of altered organ function in a
patient who is acutely ill such that homeostasis cannot be
maintained without intervention. Primary MODS is the
direct result of a well-defined insult in which organ
dysfunction occurs early and can be directly attributable
to the insult itself. Secondary MODS develops as a
consequence of a host response and is identified within
the context of SIRS and sepsis. Patients with uncontrolled
wound infection (e.g. in pressure sores) may develop
sepsis, organ failure and death
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
WICP, page 10
Opportunistic
Pathogen
An infectious agent capable of causing disease when the
hosts’ immune system is impaired
Pathogen
An infectious agent capable of causing an infectious
disease.
Phenotype
The observable characteristics or traits of an organism
such as morphology, development or behaviour
Pathogenicity
The ability of a microorganism to cause disease, also
called virulence
Planktonic bacteria
Free floating bacteria that is not attached to a surface
Prophylaxis
An agent used to prevent the spread of disease or
condition. Classically an antibiotic given once, IV, at
induction of anaesthesia to prevent surgical site infection
Purulent
Containing or comprised of pus. Pus is a collection of
infected material, usually living and dead leukocytes
Quorum sensing
A type of decision making process used by decentralized
groups to co-ordinate behaviour. Many species of
bacteria use quorum sensing to co-ordinate their gene
expression according to the local density of their
population
Resistance
The ability of a micro-organism to not be effected by
antimicrobial agents by blocking their cellular action or by
the production of an enzyme to inactivate the agent
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
Sepsis
Defined as systemic inflammatory response syndrome
(SIRS) in the presence of a known or suspected
infection. The body may develop this excessive
inflammatory response to microbes in the blood, urine,
lungs, skin, or other tissues such as infected wounds or
ulcers. An incorrect lay term for sepsis is blood poisoning,
or septicaemia;both terms are now redundant
American College of
Chest
Physicians/Society
of Critical Care
Medicine Consensus
Panel
Similar syndromes may follow burns or pancreatitis with
the systemic response to endotoxins and expression of
cytokines
Multiple organ dysfunction syndrome (MODS) may result
(eg, lactic acidosis, acute respiratory distress syndrome,
oliguria, obtundation). Septic shock is refractory
hypotension in addition, despite adequate fluid
resuscitation
Surgical site infection
Definitions of surgical site infection include:



Superficial incisional SSI: Infection involves only skin
and subcutaneous tissue of incision.
Deep incisional SSI: Infection involves deep tissues,
such as fascial and muscle layers.
Organ/space SSI: Infection involves any part of the
anatomy in organs and spaces other than the incision,
which was opened or manipulated during operation.
International Wound Infection Institute - Glossary of terms in wound infection – October 2009
Centers for Disease
Control (US)
Systemic Inflammatory
Response Syndrome
Systemic inflammatory response syndrome (SIRS) may
follow a variety of clinical insults, including infection,
pancreatitis, ischemia, multiple trauma, tissue injury,
hemorrhagic shock, or immune-mediated organ injury.
It is defined as two of:
Tachycardia >90 beats/min; Tachypnoea> 20 breaths/min
WBC >12x 109/l or <4x109/l; temp >38oC or <36oC
Tensile strength
The tensile strength of a wound is a measurement of its
load capacity per unit area. The bursting strength of a
wound is the force required to break a wound regardless
of its dimension. Bursting strength varies with skin
thickness. Peak tensile strength of a wound occurs
approximately 60 days after injury. A healed wound only
reaches approximately 80% of the tensile strength of
unwounded skin.
Virulence
Virulence is the quantitative or relative ability of the agent
to cause disease
WICP = Harding et al, Wound Infection in Clinical Practice, MEP 2008
International Wound Infection Institute - Glossary of terms in wound infection – October 2009