Bacterial Skin Infections - Yu Flashcards
impetigo ? who usually gets this
superficial skin infections- epidermis
children
Folliculitis
pyogenic infection in hair follicle - dermis
Furuncles (boils)
extension of folliculitis - dermis
Carbuncles
infection extends to the deeper subcutaneous tissue with single inflammatory response ( chills and fever due to systemic spread)
-subcutaneous
what are 3 categories of skin infections
spreading infections
abscess formation
necrotizing infections
what are spreading infections called in the epidermis and dermal lymphatics and subcutaneous fat layer
epidermis: impetigo
dermal lymphatics: erysipelas
subcutaneous fat layer: cellulitis
name three types of abscess formation
folliculitis
boils ( furuncles)
carbuncles
necrotizing infections includes what 2 things
fasciits
gas gangrene
macules
flat, non-palpable lesions
papules
palpable lesions
vescicles
palpable, fluid-filled lesions
pustules
palpable and contain pus, most neutrophils with serous fluids within or beneath epidermis
what are 3 epidermal inflammatory reactions
vesicle
pustule
bulla
vesicle
fluid accumulation
bulla
collection of serous fluid and have small numbers of inflammatory cells
erysipelas occurs where in the skin
dermis
what Direct entry into skin bacteria causes impetigo
Streptococcus pyogenes
Staph aureus
what direct entry into skin bacteria causes erysipelas
Step. Pryogenes
what direct entry into skin bacteria causes folliculits, boils ( furuncles), carbuncles
Staph. aureus
what direct entry into skin bacteria causes necrotizing fasciitis
anaerobes
microaerophiles
-usually mixed infections
what direct entry into skin bacteria causes myonecrosis gangrene
clostridium perfringens
what organism causes enteric fever and what are the skin manifestations
Salmonella typhi
Salmonella paratyphi
- “rose spots” containing bacteria
what organism causes septicemia and what are the skin manifestations
Pseudomonas aeruginosa
- ecthyma gangrenosum
what organism causes Scarlet fever and what are the skin manifestations
Streptococcus pyogenes
- Erythematous rash ( toxin)
what organism causes toxic shock syndrome and what are the skin manifestations
Staphlyococcus aureus
- rash and desquamation ( toxin)
what exogenous bacteria causes folliculitis
Staphylococci
Pseudomonas species
what exogenous bacteria causes carbuncles, furuncles
Staphylococci
what exogenous bacteria causes impetigo
Streptococci
Staphylococci
what exogenous bacteria causes erysipelas
streptococci
what exogenous bacteria causes cellulitis
streptococci
Staphylococci
haemophilus
influenza (unimmunized children)
what exogenous bacteria causes synergistic cellulitis
streptococci
enteric bacteria
anaerobes
what exogenous bacteria causes gas gangrene
clostridia
what exogenous bacteria causes necrotizing fasciitis
streptococci
enteric bactera
anaerobes
Staph aureus is what stain bacteria
gram positivve
what is Staph aureus resistant to
non-spore formers to adverse condition
is staph aureus motile
non-motile
does Staph aureus need oxygen for growth
facultatively anaerobic
Staph aureus test for catalase and coagulase
catalase: postive
coagulase: positive
Staph aureus can grow in what type of media
10% NaCl
staph aureus can cause what 4 things
abscesses
systemic diseases
food-poisoning
toxic shock syndrome
name 4 virulence factors for Staph aureus
staphylococcal toxins
exfoliative toxins
enterotoxins
toxic shock syndrome toxins
what type of bacteria is streptococcus? how does it grow on plate
gram postive
arranged in chains
how does streptococcus avoid phagocytosis
capsule
M protiens
C5a
peptidase
is streptococcus motile
non-motile
does streptococcus require oxygen
facultative anaerobic
test for catalase streptococcus
negative
what are the nutritional requirement for streptococcus
blood or serum enriched media for isolation
what virulence factor for streptococcus lyse RBC
streptolysin O and S
skin abscesses, furuncles, carbuncles are all related to what
hair follicle
for skin abscesses, furuncles, carbuncles it is a collection of what
pus within dermis and deeper skin tissue
up to 50% of cases of skin abscesses, furuncles, carbuncles are caused by what
Staph aureus
treatment for skin abscesses, furuncles, carbuncles
warm compresses to help drainage for small furuncles
Impetigo (pyoderma, impetigo contagiosa) is commonly seen in
children
impetigo (pyoderma, impetigo contagiosa) is commonly caused by
streptococcus pyogenes
staphylococcus aureus
non-bullous impetigo vesiculopustules with crusting occurs in who
children
non-bullous impetigo vesiculopustules with crusting occurs where
warm, humid conditions
non-bullous impetigo vesiculopustules with crusting risk factors
poverty, crowding, poor hygiene , underlying scabies
what are the most common causes of non-bullous impetigo vesiculopustules with crusting
streptococcus pyogenes
staphylococcus aureus
streptococcus pyogenes
staphylococcus aureus what does it look like
papules progress to vesicles surrounded by erythema
Pustular impetigo look like what
intraepidermal vesicles filled with exudate ( pus)
crusted lesions
what causes pustular impetigo
Staph. aureus
GAS
what causes Bullous impetigo
Staph aureus of phage group II that produces exfoliative toxin A (no cell adhesion)
Bullous impetigo is localized what
staphylococcal scalded skin syndrome
is there a Nikolsky’s sign for Bullous impetigo
no
Cellulitis is what type of inflammation and is accompanied by what
acute
-inflammation of draining lymph nodes
what bacteria causes cellulitis
GAS and staph aureus
what type of children get cellulitis
unimmunized children
- infection with H. influenza type B
How can an average person get cellulitis
cats or dogs
-P. multocida
what is necrotizing fasciitis
deep seated infection of the subcutaneous tissue leading to destruction of fascia and fat, but may spare skin
what does type I necrotizing fasciitis occur
after surgery
- diabetics
- peripheral vascular disease
what causes type I necrotizing fasciitis
aerobic and anaerobic bacteria
what causes type II necrotizing fasiitis
GAS
-MRSA
what bacteria causes necrotizing fasciitis? How does one get this bacteria
V. vulnificus
contaminated seawater
- mariane
Myonecrosis: necrotizing infection of muscle caused by what
C. perfringens
-associated with local trauma
what is found in the skin of myonecrosis
gas
- fascia and deep muscle spared
Staphylococcal scalded skin syndrome is called what disease
Ritter’s disease
Ritter’s syndrome is what Nikolsky’s sign and what clinical presentation
positive
- large blister with clear fluid, no organism, no leukocytes
Toxic Shock syndrome has what skin involvement? what is it associated with
cutaneous and soft tissue
- tampon use
Nikolsky sign
skin finding in which the top layers of the skin slip away from the lower layers when slightly rubbed.
Pseudomonas aeruginosa has what type of staining? shape?
Gram negative
rod
pseudomonas has what odor
grape-like
what causes pseudomonas folliculitis
immersion in contaminated water, hot tubs, swimming pools
pseudomonas folliculitis can be a secondary infection from what
acne or depilate their legs
burn wounds can have what bacterial infection
Pseudomonas aeruginosa
Mycobacterium leprae stains how and does it need oxgyen
gram +
obligately aerobic rod
how is mycobacterium leprae spread
aerosols
mycobacterium leprae can be grown in what
armadillo
footpads of mice
where does mycobacterium leprae grow in body
skin histiocytes ( skin macrophages )
- endothelial cells
- Schwann cells of peripheral nerves
how does one diagnose lepromatous leprosy
acid fast stain of nasal mucosa
what are two forms of leprae
tuberculoid leprosy
lepromatous leprosy
p. aeruginosa bacteremia in neutropenic patients clinically present how
ecthyma gangernosa
clinical presntation for tuberculoid leprosy
red-blotchy lesions with anesthetic areas
tuberculoid leprosy has what immune response
cell-mediated response - Th1
Lepromatous leprosy has what immune response
humoral
Th2
lepromatous leprosy is analogous to what other bacteria
miliary TB
treatment for lepromatous leprosy
dapsone
ribiospfampin
clofazimine
- 2 years
treatment for tuberculoid leprosy
dapsone
rifampin
- 6 months
Bacillus anthracis is what type of bacteria
gram +
spore forming
name 3 virulance factors for Bacillus anthracis
EF- edema factor
LF- lethal factor
PA protective antigen
what makes up edema toxin
edema factor and protective antigen
what makes up the Lethal toxin
lethal factor and protective antigen
what does edema factor cause
increased intracellular cAMP-impaired flow of ions and water
what activates the edema factor
human calmodulin
role of lethal factor
induces macrophage to produce high levels of cytokines that trigger shock.
role of protective antigen
promotes entry of EF into phagocytic cells
how is bacillus anthracis spread
inhalation of aerosolized spores
what does chest X-ray look like with Bacillus anthracies
mediastinal widening
where does Bacillus anthracies replication occur in the body
lung with local exotoxin release
what is the most common symptoms
cutaneous anthrax
what is the clinical presentation for anthrax
- painless papule at site of inoculation
- progress to ulcer
- necrotic eschar
- malignant pustule: round black lesion with a rim of edema
what should the microscopic exam reveal about B. antrhacis
from papules
- no spires
- serpentine chain of bacilli
culture results for B. anthracis
non-hemolytic, sticky, colonies
what test confirms B. anthracis
biochemical tests
treatment for B. anthracis
Penicillin
Ciprofloxacin
Doxycycline
60 days
how does one protect themselves form B. anthracis
- inactivated cell-free product as vaccine
- live attenuated vaccine
