Infections Of The Skin Flashcards
What are features of the skin as a defensive barrier?
\+ Epidermis: hard horny layer of cells \+ Surface is dry \+ Constant sloughing \+ Acidic pH \+ Sweat secretion \+ Rich blood and lymphatic supply \+ Produces antimicrobial substances e.g - fatty acids - sebum - defensins
What are examples of normal microbiota?
+ Coagulase-negative Staphylococci
- Staphylococcus epidermidis
- Staphylococcus aureus
+ Streptococcus pyogenes
+ Propionibacterium acnes
+ Corynebacterium sp.
+ Candida sp.
Where is the site of infection for ringworm?
Keratinised epithelium
What is the site of infection for impetigo?
Epidermis
Where is the site of infection for folliculitis?
Hair follicles
Where is the site of infection for cellulitis?
Subcutaneous fat
Where is the site of infection for necrotising fasciitis?
Fascia
Where is the site of infection for gas gangrene?
Muscle
What are the routes of infection?
Via:
+ Skin
- pores
- hair follicles
+ Wounds
- scratches
- cuts
- burns
+ Bites
- insects
- animals
Name some bacterial infections of the skin
+ Staphylococcus aureus
+ Staphylococcus pyogenes
+ Pseudomonas aeruginosa
+ Myobacterium tuberculosis
SOME MAY BE TOXIN MEDIATED
What are features of streptococcus pyogenes?
\+ Cocci morphology \+ Grows in chains \+ Gram positive \+ Group A Streptococcus (GAS) \+ Multiple virulence factors \+ Beta-haemolytic
What are features of staphylococcus aureus?
\+ Cocci morphology \+ Grows in clusters \+ Gram positive \+ Causes huge range of illnesses \+ Antibiotic resistant strains - MRSA - VRSA \+ Multiple virulence factors \+ Direct infection or effect of toxin
What are features pseudomonas aeruginosa?
\+ Coccobacillus morphology \+ Gram negative \+ Monotrichous flagellum \+ Opportunistic pathogen \+ Colonises catheters etc. \+ Produces exotoxin A
What are different forms of skin lesions?
+ Macule
- raised
- red
- local inflammation
+ Papule
- raised
- red
- more marked inflammation
+ Vesicle
- small blister
+ Ulcer
- disruption of epithelium
What is an abscess?
Collection of pus; pustule
What is a (cutaneous) vesicle?
Blister; bullae (pl.); fluid filled sac
What is pyoderma?
Pus-forming skin infection; cutaneous abscess
What is impetigo?
Vesicles developing into rupturing pustules then forming dried crusts
What is ecthyma?
Rupturing vesicles leading to erythematous lesions and dried crusts
What is folliculitis?
Inflammation at hair follicle
What is a furuncle?
Boil; deep folliculitis
What is a carbuncle?
Collection of boils
What is erysipelas?
Erythema and inflammation of superficial dermis
What is cellulitis?
Erythematous inflammation affecting deeper dermis and subcutaneous fat
