Download Chapter 23 Skin Infections

Chapter 23
Skin Infections
Medgar Evers College
Biology 261
Prof. Santos
Anatomy and Physiology
• The skin is a large complex organ with
many functions. These functions include
temperature regulation, vitamin D
production, helping the immune system,
forming a protective barrier against
environmental conditions.
Normal microbiota of the skin
1) Diphtheroids are gram + rods
responsible for body odor, acne, fatty
acid secretions from their metabolism
keep skin acidic.
2) Staphylococci, gram + cocci arranged in
clusters normally present on the skin.
They help prevent the colonization of
pathogens on the skin.
3) Fungi- Malassezia are yeast normally
found on the skin. They normally cause no
harm but can give rise to a serious skin
disease in immuno compromised patients
like people infected with HIV.
Bacterial skin infections
• Folliculitis is the name given to a group of
skin conditions in which there are inflamed
hair follicles. The result is a tender red
spot, often with a surface pustule. The
agent of infection is S.aureus
• A carbuncle is a skin infection that often
involves a group of hair follicles. The
infected material forms a lump, called
mass, which occurs deep in the skin.
• Most carbuncles are caused by the
bacteria staphylococcus aureus. The
infection is contagious and may spread to
other areas of the body or other people.
• A carbuncle is made up of several skin boils
called furuncles. The infected mass is filled with
fluid, pus, and dead tissue. Fluid may drain out
of the carbuncle, but sometimes the mass is so
deep that it cannot drain on its own.
• Carbuncles may develop anywhere, but they are
most common on the back and the nape of the
neck. Men get carbuncles more often than
women.
Bacterial
disease
cause
symptoms
Strain of S.
Tender red
scalded skin aureus that rash, fever,
syndrome
produces an large blisters
exfoliatin
toxin.
Exfoliatin is
a toxin that
destroys the
material that
binds
together the
layers of the
epidermis.
Staphylococcal
pathogenesis
treatment
Toxin is
produced by
pathogen at
infection
site, carried
into
bloodstream
and then in
the
epidermis it
causes a
split.
Penicillinase
resistant
penicillin
and removal
of dead
tissue
Virulent factors of S.aureus
• Protein A, an Fc receptor
• Coagulase, an enzyme that clots plasma
and coats the bacterial cell to prevent
phagocytosis.
• Hyaluronidase, an enzyme that helps to
break down ECM material and helps the
pathogen spread.
• Staphylokinase, an enzyme to break down
fibrin and helps the pathogen spread.
bacterial
disease
cause
symptoms
pathogenesis
treatment
Impetigo
Streptococci
pyogenes
and
Staphylococ
cus aureus
Blisters that
break
releasing
plasma and
pus, golden
crusts,
enlargement
and
tenderness
of lymph
nodes
Pathogen
enters skin
through a
break
Antibiotic
and clean
the skin area
regularly.
bacterial
disease
cause
symptoms
pathogenesis
treatment
Rocky
mountain
spotted
fever
Rickettsia
rickettsii, an
obligate
intracellular
bacterium
Muscular
pain,
headache,
fever,
hemorrhagic
rash that
starts on the
extremities
Tick bite
introduces
the
pathogen, it
multiplies,
invades
bloodstream
, then
invades
endothelial
cells and an
endotoxin
accounts for
pathology.
Avoid tick
infected
areas, tick
repellent,
doxycycline,
chloroamph
enicol.
bacterial
disease
cause
symptoms
pathogenesis
treatment
Lyme
disease
Borrelia
burgdorferi
1-Enlarging red
rash at site of
infection, fever,
malaise,
headache,
enlargement of
lymph nodes
2-dizzy spells,
fainting, pain
when moving
eyes
3-localized
pain, paralysis,
joint pain and
swelling
Infected tick
deposits
pathogen into
host,
multiplies,
travels
through
bloodstream,
the immune
system reacts
causing tissue
damage
Prolonged
antibiotic
treatment,
tick
repellent,
protective
clothing
during
camping
trips or
hiking.
Viral
disease
cause
symptoms
pathogenesis
treatment
Varicella or
chicken pox
Varicella
zoster virus
Itchy lumps
and blisters,
fever, latent
infection can
be
manifested
as shingles
later in life.
Incubation
period is 1021 days
Upper
respiratory
viral
multiplicatio
n followed
by
disseminatio
n by the
bloodstream
to the skin.
Virus attacks
cells causing
blisters.
Vaccination,
an antiviral
medication
can be given
such as
acyclovir.
viral
disease
cause
symptoms
pathogenesis
treatment
German
measles or
rubella
Rubella
virus
A mild fever
and cold like
symptoms, a
rash that
starts at the
forehead
and face,
enlarged
lymph nodes
behind the
ears
The virus
replicates on
the upper
respiratory
tract, then
travels via the
bloodstream
to other parts
of the body.
Antibodyantigen
complexes
lodge in the
skin causing
the rash.
Attenuated
Rubella
virus
vaccine but
no specific
antiviral
medication
recommend
ed.
viral
disease
cause
symptoms
pathogenesis
treatment
Measles or
rubeola
Rubeola
virus
Rash,
cough, fever,
weepy eyes,
nasal
discharge
Virus
replicates on
the upper
respiratory
tract, travels
to other parts
via
bloodstream
such as lungs,
skin, and
brain. T cells
attack virus
on skin
causing the
rash.
Attenuated
measles
vaccine after
1st birthday
and 2nd dose
before
starting
school. No
antiviral
medication
recommend
ed.
Other viral diseases
• Include warts caused by the
papillomavirus, fifth disease (Slapped
cheek rash) caused by the parvovirus B19, and Roseola. This is a childhood rash
with fever caused by the human herpes
type 6 virus.
Fungal infections of the skin
• Include diaper rash caused by Candida
albicans, Jock itch, body ring worm, and
athlete’s foot.
• Cutaneous mycoses are infections of the
upper layer of the skin, hair and nails.
They do not invade deep tissue.