Skin Infections Flashcards
What type of bacteria is s.aureus, what is a virulence factor of it and what disease can it cause?
gram-positive cocci (appears purple)
PVL toxin (panto valetine leukocidin toxin - kills white cells)
causes angular cheilitis (inflammation at angles of mouth) and necrotising pneumonia
What are the two types of s.aureus?
methicillian sensitive s.aureus (MSSA)
methicillin resistant s.aureus (MRSA)
What is PVL and how does it work?
exotoxin released by s.aureus
once hits target cells, coalesces forms pores which release inflammatory mediators from target cells
What is clinical effect/disease of community aquired MRSA?
necrotising pneumonia
What can necrotising pneumonia present as?
recurrent skin infections (look like spider bites)
What type of bacteria is s.pyogenes, what is a virulence factor of it and what disease can it cause?
strep pyogenes (gram positive cocci)
superantigens and toxic shock syndrome (causes huge dysregulation of immune response)
cellulitis (skin infection in dermis)
What type of bacteria is strep.angiosus, what is a virulence factor of it and what disease can it cause?
gram positive cocci
intermedilysin (cytotoxin that leads to lysis of cells)
dental abcess
What type of bacteria is clostridium welchii, what is a virulence factor of it and what disease can it cause?
anaerobic gram-positive bacillus
alpha toxin (lecithinase - fatty acid that breaks down cell membranes)
gas gangarene
What test is used to confirm c.welchii?
nagler reaction
detects alpha toxin
What is gas gangrene called?
clostridial myonecrosis
What type of virus is herpes simplex group, what is a virulence factor of it and what disease can it cause?
DNA virus
virulence factor = cell lysis
herpes labialis (oral herpes)
What type of fungi is candida albicans, what is a virulence factor of it and what disease can it cause?
dimorphic oppurtunastic fungus
phospholipase (breaks down phospholipids)
oral thrush
What are examples of diseases that affect the epidermis?
What are their causes/clinical presentations?
impetigo and angular cheilitis
caused by staph aureus
presents as inflammation/ blistering
What is an exampleof disease that affects the dermis?
What is it’s cause/ presentation?
erysipelas
butterfly erythma of the face
group a strep (s. pyogenes)
What are examples of diseases that affect the hair follicles?
What are their causes/clinical presentations?
folliculitis (staph aureus, inflammation of individual follicles, pus involvement)
boils (furuncle) (staph aureus, larger inflammation, more pus)
carbuncles (staph aureus, multiple heads, inflammation, blistering)
What is an exampleof disease that affects the subcutaneous fat?
What is it’s cause/ presentation?
cellulitis
demarcation of erythema
strep pyogenes/ mixed infection
What is an example of disease that affects the fascia?
causes/ presentation?
necrotising fascilitis
strep pyogens, staph aureus, mixed infection
inflammation, tissue necrosis, pus
What is an example of disease that affects the muscle?
causes/ presentation
myonecrosis (gangrene)
clostridium welchii
black/purple skin, blood flow cut off
What microorganisms cause bit wound infections in both humans/animals?
- Humans – mixed anaerobes
- Animals – Pasteurella multicoda
What are the treatment prinicples for skin/tissue infections?
- Diagnosis
- Surgical debridement
- Microbiological specimens
- Antibiotics
- Review
When is surgical debridement used?
severe infection (abcess)
How are microbiological specimens taken during surgical debridement?
aspirate of pus during draining
What antibiotic is used to treat MSSA and what antibiotic is used to treat MRSA?
MSSA = flucloxacillin
MRSA = vancomycin
What antibiotic is used to treat S.pyogenes and S.anginosus (dental alveolar infection)?
penicllin
