Transcript Chapter 24 Wound Infections

Chapter 24
Wound Infections
Bio 261
Medgar Evers College, CUNY
Prof. Santos
Classification of wounds
– Incisions: produced by knife or other sharp object
– Punctures: result from penetration by small sharp
object
– Lacerations: occur when tissue is torn
– Contusions: produced by blow that crushes tissue
– Abrasions: occur when epidermis is scraped off
– Gunshot wounds: caused by bullets, other projectiles
– Burns: caused by heat, electricity, chemicals,
radiation, or friction
Anatomy and Physiology
1- Tissue components exposed during a
wound (break in skin or damage to skin)
include collagen, fibronectin, fibrin, and
fibrinogen.
2-They provide receptors to which potential
pathogens can attach to.
3- Collagen is a fibrous material that is the
main supportive protein in skin, tendons,
scars, and other body components.
4- Fibronectin is a glycoprotein that both
circulates the body and is a component of
body tissue. In a tissue, it binds cells
together.
5- Fibrinogen is a soluble blood protein that
is converted to a fibrous material called
fibrin after a wound occurs. This results in
the formation of clots in the damaged
vessels.
This stops the flow of blood as the first step
in the repair process.
6- Wound healing begins with the outgrowth
of connective tissue cells called fibroblasts
and capillaries from the surface of wound
to form nodular, red, translucent material
called granulation tissue. Granulation
tissue is bright red, differentiates into new
capillaries and bleeds easily.
7- granulation tissue fills the void created by
the wound, contracts, and is converted to
collagen that composes the scar tissue
and eventually covered by skin or mucous
membrane.
Abscess formation
• An abscess is a localized collection of pus
surrounded by a body tissue. It is composed of
living and dead white blood cells, components of
tissue breakdown, and infecting organisms.
• There are no blood vessels in an abscess since
they have been pushed aside or destroyed. This
results in poor delivery of medication or
antimicrobial drugs to the area.
• An area of inflammation separates the abscess
from normal tissue. This localizes the infection.
• Microorganisms stop multiplying in an
abscess so antimicrobial drugs such as
penicillin has no effect.
• The chemical nature of pus interferes with
antimicrobial drugs.
• An abscess must burst to surface or be
drained surgically in order to effect a cure.
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Microorganisms
Epidermis
Dermis
Capillary
Neutrophils
1
Microorganisms enter the tissue from
a wound or from the bloodstream.
2
Blood vessels dilate, and leukocytes migrate
to the area of the developing infection.
Pus
Blood clots
Blood clots
3
Pus forms and an abscess develops;
clotting occurs in adjacent blood vessels.
4
Buildup of pressure causes the abscess to expand in
the direction of least resistance; if it reaches a body
surface, it may rupture and discharge its contents.
Anaerobic wounds
• Allow anaerobic organisms such a
Clostridium tetani to colonize and cause
infection.
Staphylococcal wound infections
• 2 species of Staphylococci account for most
human wound infections; Staphylococcus
aureus and Staphylococcus epidermidis
• Symptoms include the discharge of pus,
inflammatory reaction with swelling, redness,
and pain
• Epidemiology; Staph is a normal habitant of the
skin and nasal carriers have a greater chance of
infection than noncarriers.
• Old age, poor health, prolonged hospital
stay, immuno-supression also contribute
to the progression of disease.
• Treatment; cleaning and removing dirt,
and anti Staph medication given to
eliminate nasal carrier state or prior to
surgery.
Group A Streptococcal flesh eaters
• Streptococcus pyogenes can colonize wounds
and cause severe infections such as necrotizing
fasciitis or flesh eating disease or worst
streptococcal toxic shock.
• Symptoms; severe pain, swelling, fever and
confusion. The overlying skin becomes stretched
and discolored due to swelling. Shock and death
will follow if treatment is not received shortly
after infection.
• Causative agent is S. pyogenes. It is a
beta hemolytic, aerotolerant, gram positive
chain forming coccus with Lancefield
group A cell wall polysaccharide.
• They possess at least 2 extracellular
products; pyrogenic exotoxin A and
exotoxin B.
• Exotoxin A is a superantigen that causes shock
and Exotoxin B is a protease that destroys tissue
by breaking its proteins.
• Pathogenesis; S. pyogenes bind to fibronectins
in tissue that help in colonization. They destroy
Fascia or bands of fibrous tissues that underlie
the skin and surround muscle and body organs.
Intense swelling occurs due to fluid entering the
area as a result of increased osmotic pressure
from tissue breakdown into small molecules.
• Prevention; urgent surgery is needed to
relieve the pressure of the swollen tissue
and remove dead tissue. Amputation is
sometimes needed to rid patient of toxin.
Pseudomonas aeruginosa
infections
• Agent of infection: P. aeruginosa is
aerobic, gram negative, rod shaped with a
single flagellum. It produces 2 pigments
that often color the area of infection green.
• Symptoms; green coloration, chills, fever,
skin lesions, and shock.
• Prevention; carefully remove dead tissue
from wound, clean area, application of
antibacterial cream and antibiotics.
Anaerobic bacterial infections
Disease
Cause
Tetanus or
lockjaw
Clostridium
tetani
*release of
Symptoms
treatment
Restlessness Tetanus
, irritability,
antitoxin
difficult
tatanospasmin, swallowing,
a toxin that acts muscle pain
against nerve
and spasm in
cells
jaw,
abdomen, or
entire body
Anaerobic bacterial infections
Disease
Cause
Symptoms
treatment
Gas
gangrene
(clostridial
myonecrosis)
Clostridium
perfringens
*secretion of
alpha toxin
that kills
wbc’s and
tissues
Severe pain,
gas and fluid
seep from
wound,
blackening of
skin, shock
and death
follows!
Clean
wounded
area, surgical
removal of
dirt and dead
tissue,
oxygen,
antibiotics.
Anaerobic bacterial infections
Disease
Cause
symptom pathoge
s
nesis
Lumpy Jaw or Actinomyces Chronic
actinomycosis israelii
disease,
painful
swellings
under the
skin, involves
face and
neck, chest or
in the genital
tract of
women.
These
swellings can
open to
release pus.
Usually
begins in
mouth area
and extends
outward.
treatmen
t
Long
treatment
due to slow
growth, a
number of
antibacterial
medications
can be
given.
Bacterial bite wound infections
Disease
Cause
Symptoms
treatment
Pasteurella
multocida
infections
from dog,
cat,
monkey,
human bite.
Pasteurella
multocida
*gram –
coccobacill
us lives in
mouth
Spreading
redness,
tenderness,
swelling,
discharge
of pus
Treatment
with
penicillin is
effective if
given early
Bacterial bite infections
Disease
Cause
Cat scratch Bartonella
disease
henselae
Symptoms
treatment
Pimple
appears at
the bite,
local lymph
node
enlargeme
nt, fever,
and
convulsions
Avoid rough
play with pet
cat, flea
control in
cats, apply
antiseptic,
and
antimicrobial
treatment
Bacterial bite infections
Disease
Cause
Symptoms
treatment
Streptobacillary
rat bite infection
Streptobacillus
moniliformis
*some develop
L- form variants
which lack a cell
wall
Chills, fever, Penicillin and
muscle
control rat
aches,
population
headache,
vomiting,
rash and pain
in the large
joints
Bacterial bite infections
Disease
Cause
Human bite Mixed
infection
mouth flora
including
staph,
anaerobic
streptococc
us
Symptoms
treatment
Pain,
swelling,
drainage of
foul
smelling
pus
Avoid
human
altercations
that might
lead to
biting.
Fungal wound infections
Disease
Cause
Symptoms
treatment
Rose
Gardener’s
disease
Sporothrix
schenckii
Painless,
ulcerating
nodules
appearing in
a linear
fashion
Protective
clothing,
amphotericin
B or
itraconazole