Infections of the Skin Flashcards
Explain the role of microbiota in and on the body
Offers protection by competing with pathogens for colonisation sites.
Some produce antibiotic substances which suppresses the growth of competing organisms. Some produce toxins to inhibit other micro-organisms
Describe how skin acts as a defence barrier
It has an acidic pH which makes it uninhabitable, it also secretes sweat and produces antimicrobial substances such as fatty acids, sebum and defensins
Name two examples of normal skin microbiota
Coagulase-negative staphylococci (epidermidis and aureus)
Where can skin infections occur and give an example
Keratinised epithelium - ringworm Epidermis - Impetigo Hair follicles - folliculitis Subcutaneous fat - cellulitis Fascia - necrotising fasciitits Muscle - gas gangrene
Describe routes of infection
Skin - pores and hair follicles
Wounds - scratches, cuts and burns
Bites - Insect and Animal.
Describe some of the features of streptococcus Pyogenes
Gram positive cocci that grows in chains.
Its a group A, beta-haemolytic (makes it very dangerous)
Define haemolytic
Involving the rupture or destroying of red blood cells.
Describe some features of Staphylococcus aureus
Gram -positive cocci
Resistant to methicillin and vancomysin,
Causes a wide range of illnesses
Describe some of the features of Pseudomonas Aeruginosa
Coccobacillus (between cocci and bacilli) shaped, gram negative.
Monotrichous flagellum.
Opportunistic bacteria so will colonise in catheters ect.
Describe the different forms of skin lesions and how they appear
Macule - Flat and red, local inflammation
Papule - Raised and red, more marked inflammation
Vesicle - small blister
Ulcer - Disruption of epithelium
Define Abscess
Collection of pus
Define Cutaneous vesicle
Blister - fluid filled sac
Define Impetigo
Vesicles developing and rupturing into pustules then form dried crusts
Define Ecthyma
Ruptures vesicles that lead to erythematous (redness of mucosa membrane) lesions
Folliculitis
Inflammation of hair follicle.