Dermatology Flashcards
What is impetigo?
A common superficial bacterial infection of the skin
What are the two clinical forms of impetigo?
- Non-bullous impetigo (70% of cases)
2. Bullous impetigo (fluid-filled bullae >5mmin diameter)
If impetigo develops as a secondary complication - what are the pre-existing conditions that it tends to develop from? (3)
- Eczema
- Scabies
- Chickenpox
How is impetigo spread?
Either through close contact with an infected person or indirectly via contaminated objects such as toys, clothing or towels
- the bacteria enter the skin through breaks caused by minor trauma (such as insect bites or scratches) or underlying skin conditions (e.g. eczema)
- the incubation period is 4-10 days
What are the causative agents of impetigo non-bullous impetigo?
- Staph. aureus
2. Strep. pyogenes
What is the causative agent of bullous impetigo?
Staph. aureus - bullae form when exfoliative toxins produced by staph. a, cause loss of cell adhesion in the superficial epidermis
Impetigo caused by which strain of staph aureus is becoming more and more common?
MRSA
What are the risk factors for developing impetigo? (5)
- Skin trauma
- Pre-existing skin disease
- Hot/humid weather
- Poor hygiene
- Crowding
What is the annual incidence of impetigo in children up to 4 years of age?
2.8%
What are the complications of impetigo if for example the person is immunosuppressed or it develops in a neonate? (7)
- Acute glomerulonephritis
- Cellulitis
- Lymphangitis
- Staphylococcal scalded skin syndrome
- Osteomyelitis and septic arthritis
- Septicaemia
- Scarlet fever
What are the clinical features of non-bullous impetigo?
- Lesions begin as thin walled vesicles or pustules which release exudate forming a characteristic golden/brown crust. Once crusts dry they separate, leaving mild erythema which is self-limiting and resolves after 2-3 weeks without scarring
- Usually asymptomatic but may be mildly itchy
- Systemic features are uncommon but regional lymphadenopathy and fever may occur in severe cases
Where is it most common for non-bullous impetigo to develop?
- Peri-oral
- Peri-nasal
- Limbs
- Flexures (such as axillae)
How does bullous impetigo appear?
- Lesions appear as flaccid fluid filled vesicles and blisters which can persist for 2-3 days. Blisters rupture leaving a thin yellow/brown crust. Healing usually occurs within 2-3 weeks without scarring.
- Most common on the flexures, face, trunk and limbs
What is the recommended treatment for mild and very localised non-bullous impetigo?
Topical fusidic acid TDS for 5 days (or if caused by MRSA then topical mupirocin)
What is the treatment for widespread impetigo or bullous impetigo?
Either:
Oral flucloxacillin QDS for 7 days
OR
Oral calrithromycin BD for 7 days
What is nappy rash?
An acute inflammation reaction of the skin in the nappy area, which is most commonly caused by an irritant dermatitis. It is also known as napkin dermatitis or diaper dermatitis
Why does nappy rash occur?
The skin barrier function may be compromised by:
1. Skin maceration (excess hydration)
2. Friction
3. Prolonged skin contact with urine and faeces
…these factors activate faecal enzymes which further act as skin irritants
What does skin irritation with nappy rash predispose to the risk of?
Colonization and secondary infection with e.g. candida albicans (thrush) and staph. aureus infection
How common is nappy rash and in which age is the peak incidence?
Estimated to occur in at least 25%, but may be underreported, and peak age between 9 and 12 months
What are the risk factors for nappy rash? (7)
- Skin care practices (e.g. how often the area is cleaned/nappy changed)
- Type of nappy used
- Exposure to chemical irritants e.g. soaps, detergents
- Skin trauma e.g. over vigorous cleaning
- Medication e.g. recent broad spectrum ABX predispose to thrush
- Gestational age - pre-term infants more at risk due to reduced barrier function of immature skin
- Diarrhoea
