Skin Infections Flashcards
What is the name of this disease? [1]
Which pathogen is the most likely cause of this infection? [1]
Impetigo;
Staph. aureus most common
Which pathogen causes this symptom? [1]
Candida albicans
[] are a unique population of tissue-resident macrophages that form a network of cells across the epidermis of the skin, but which have the ability to migrate from the epidermis to draining lymph nodes (LN)
Langerhan cells
What pathogen causes this symptom? [1]
HSV-1
Describe how your skin is a hostile environment [3]
Physical barrier
* Dry
* Desquamates (constant shedding)
Chemical barrier
* Eccrine, apocrine and sebaceous glands: feed good bacteria
* Unsaturated fatty acids (oleic acid)
Bacterial interference
* Colonisation by non pathogenic skin flora (microbiome of the skin): outcompete bad bacteria
Normal skin biome is made up from which:
bacteria [3]
yeasts [3]
viruses [3]
bacteria:
* Staphylococcus
* proprionobacteria
* corynebacteria
yeasts
* malassezia,
* aspergillus
* Cryptococcus
viruses:
* HPV
* EBV
* HHV8
Role of normal skin flora? [2]
Produces molecules that inhibit colonisation of other species
Educates the innate and adaptive immune response (Inflammation)
Where are the 3 main microenvironments of the skin? [3]
- Axilla, perineum and toe webs (moist)
- Hands, face and trunk (oily)
- Upper arms and legs (dry)
Which is the major inhabitant making up more than 90% of the flora? [1]
Staphylococcus epidermidis
Which species of your normal skin flora:
Makes up 90% of the flora? [1]
Is found in nose, perineum, vulvar skin? [1]
Feeds off sebum and cellular debris and colonisation starts when sebaceous glands become more active?
Makes up 90% of the flora: Staphylococcus epidermidis
Is found in nose, perineum, vulvar skin: Staphylococcus aureus
Feeds off sebum and cellular debris and colonisation starts when sebaceous glands become more active: Propionibacterium acnes
Which bacteriia is found more in the nose, perineum & vulvar skin? [1]
(occurrence in nasal passages varies with age)
Staphylococcus aureus
Main pathogen that causes folliculitis? [1]
Staphylococcus aureus
Describe the relationship of Staphylococcus epidermidis
and Staphylococcus aureus in a period of atopic dermatitis? [1]
S. epidermidis increases as an antagonistic response to an increase in S. aureus population in atopic dermatitis
How does folliculitis occur? [1]
Infection and inflammation of one or more hair follicles
Which pathogen causes hot tub folliculitis? [1]
Pseudomonas aeruginosa
Treatment for folliculitis? [3]
Oral antibiotic
Retinoic acid & Vit. A: reduces amount of sebum
Two primary pathogens that cause impetigo? [2]
Staphylococcus aureus or Streptococcus pyogenes
Tx of impetigo?:
Simple cases [1]
Severe cases? [1]
Most people? [1]
Oral or topical antibiotic for severe cases that have spread to other body areas
NICE recommends 1% hydrogen peroxide cream for simple cases
But most people will get better without treatment within 3 weeks
Describe the pathogenensis of cellulitis [2]
Infection of the dermis and subcutaneous fat caused by Staphylococcus aureus or Streptococcus pyogenes due to break in skin
What is cellulitis in the face called? [1]
How does it differ to cellulitis in location? [1]
Most common pathogen? [1]
Erysipelas (cellulitis of the face) but just in the dermis and not in subcutaneous fat
Streptococcus pyogenes
What is this skin infection? [1]
Which pathogen causes this? [1]
Scalded skin syndrome:
Staphylococcus aureus
Describe the pathophysiology of scalded skin syndrome [2]
Exotoxins are proteases that destroy desmosomes holding keratinocytes in granulosum and spinosum layers together:
Causes widespread fluid filled blisters that easily break
Treatment of scalded skin syndrome? [2]
Treatment:
* Conservative: rehydration antipyretics
* Parenteral antibiotics
Name this disease [1]
Necrotising fasciitis
What pathogen causes this symptom? [1]
Human papillomavirus: causes viral warts and verruca (plantar warts)
Describe pathophysiology of HPV causing warts and verrucas [3]
DNA virus
Infects basal cells of the epidermis
Lesions arise from proliferation of infected basal keratinocytes
Causes hyperkeratosis, acanthosis and hypergranulosis, rete ridge elongation and large blood vessels at dermoepidermal junction
Name this symptom of Herpes virus [1]
Herpatic whitlow
Describe what the symptoms of a shingles rash is like [1]
Typically single wide stripe either on the left or right side of the body
What causes this symptom? [1]
Where are patients commonl affected? [1]
How do patients commonly present? [1]
Molluscum contagiosum: water warts
Moist areas more common such as abdomen, groin, axilla
Pink, smooth with dimple in the middle (full of dead cells)
What causes this symptom? [1]
Candida albicans: Opportunistic infection genital thrush, intertrigo, oral plaques, paronychia (nail fold)
What causes this symptom? [1]
Pityriasis versicolour (tinea versicolour)
Describe the pathophysiology of Pityriasis versicolour [1]
Which populations does it impact more? [1]
Overgrowth of commensal yeast Pityrosporum orbiculare; young adults, brown/pink scaly patches, hypopigmented if suntanned
Affects young adults and slightly more men than women:
It is not contagious infection is not due to poor hygiene usually occurs in warmer months white, salmon or light brown patches chest,back, arms and legs
More common in hot humid climates and only affects people that sweat heavily
Often clears during the winter months and reappears each summer
Describe pathophysiology of scabies [2]
Sarcoptes scabiei (hominis) female mite infestation: 10-15 mites
Symptoms are an allergic reaction to mites that burrow and lay eggs in skin
Lyme disease is caused by ticks spreading which bacteria? [1]
Describe symptoms [2]
Borrelia bacteria
- Expanding red rash 70-80% of patients
- Rash is oval not itchy or painful and resolves (untreated) in around 4 weeks accompanied with flu like systemic illness
What causes this symptom? [1]
Lupus vulgaris: TB of the skin
Where does lupus vulgaris commonly occur? [2]
Painful cutaneous tuberculosis skin lesion most often on the face around nose, eyelids, lips and cheeks.
May develop into disfiguring skin ulcers if left untreated
What is Scrofuloderma (scrofula)?
lymphatic dissemination of pulmonary TB
