BACTERIAL SKIN INFECTIONS Flashcards
What is erysipelas?
A localised skin infection caused by streptococcus pyogenes
In simple terms it is a more superficial, limited version of cellulitis
It affects the dermis and upper subcutaneous tissue only
Clinical features of erysipelas?
Sharply defined borders of raised, swollen, firm, erythematous skin
Commonly affects the lower limbs but can cause a “butterfly” distribution on the face
What causes erysipelas?
Almost all are caused by group A beta-haemolytic streptococci
Treatment of erysipelas?
Flucloxacillin
What is cellulitis?
A bacterial infection of the dermis and deeper subcutaneous tissues
What causes cellulitis most commonly?
Streptococcus pyogenes
Less commonly - staph aureus
Clinical features of cellulitis?
Unilateral usually. Most commonly on shins
Erythema
Swelling
Systemic upset - fever, malaise, nausea
Blisters and Bullae may be seen with more severe disease
Diagnosis of cellulitis?
Clinical - no further investigations required
Bloods and cultures only if septicaemia is suspected
What classification do we use to guide how we manage pt with cellulitis?
The Eron classification
Outline the Eron classification?
Class 1 - no signs of systemic toxicity and pt has no uncontrolled comorbities
Class 2 - pt is systemically unwell or has a co-morbidity which may complicate/delay resolution of infection
Class 3 - significant systemic upset or unstable co-morbidities that may interfere with a response to treatment, or a limb-threatening infection due to vascular compromise
Class 4 - sepsis syndrome or a severe life-threatening infection e.g. necrotising fasciitis
Which patients with cellulitis should be admitted to hopsital for IV antibiotics?
Eron Class 3 or 4 cellulitis
Severe or rapidly deteriorating cellulitis
<1 or frail
Immunocomprosed
Significant lymphoedema
Facial cellulitis or periorbital cellulitis
Management of Eron Class 1 cellulitis?
Antibiotics - oral Flucloxacillin as first-line Tx
Management of Eron Class 2 cellulitis?
Admission may not be necessary if the facilities and expertise are available in the community to give intravenous antibiotics and monitor the person - check local guidelines
Management of Eron Class 3-4 cellulitis?
Admit
NICE recommend oral/IV co-amoxiclav, clindamycin, cefuroxime, ceftriaxone
Risk factors for erysipelas or cellulitis?
Previous infection
Venous insufficiency
Immunodeficiency
Breaks in skin barrier - bites, ulcers, psoriasis, eczema
Obesity
Fissured toes/heels due to athletes foot
What is impetigo?
A superficial bacterial skin infection that can be a primary infection or a complication of an existing skin condition such as eczema, scabies or insect bites
It’s common in children, particuarly during warm weather
What typically causes impetigo?
Staph aureus or streptococcus pyogenes
Where does impetigo typically occur on the body?
On the face, flexure and limbs not covered by clothing
How is impetigo spread?
By direct contact with discharges from the scabs of an infected person
The bacteria invade the skin through minor abrasions and then spread to other sites by scratching
How does impetigo present?
Erythematous macule that vesiculates or pustulates
Characteristic golden crust
Management of limited, localised impetigo?
Hydrogen peroxide 1% cream
Other options - topical fusidic acid, topical mupirocin
Management of extensive impetigo?
Oral flucloxacillin or oral erythromycin if penicillin-allergic
School exclusion for impetigo?
children should be excluded from school until the lesions are crusted and healed or 48 hours after commencing antibiotic treatment
What is Folliculitis?
An inflammatory condition of the hair follicles, typically presenting as papules or pustules
Occurs anywhere on the body but the palms and soles are usually exempt
Aetiology of Folliculitis?
Folliculitis can be caused by various factors, predominantly bacterial infections, specifically Staphylococcus aureus. It can also result from Gram-negative organisms, often following long-term antibiotic therapy for conditions like acne.
A particular form, eosinophilic folliculitis, is sterile and most commonly arises in the context of immunosuppression, like in HIV patients. The causative factor in this case is not an infection but a reactive condition associated with the immune status.
Presentation of Folliculitis?
Papules and pustules
You may see a hair coming out of these bumps
The affected skin can feel painful, hot and may be itchy
What is hot tub folliuclitis?
Folliculitis caused by an infection with pseudomonas aeruginosa from improperly santisided hot tubs or spas
Management of folliucltiies?
Mild cases dont need treatment and will clear within 7-10 days
Antibacterial soaps can be used
Fusidic acid can be used for localised areas
Oral antibiotics may be needed if folliuclities is severe or widespread
What is a furuncle?
A boil - a painful, pus-filled bump that forms under your skin when bacteria infect a hair follicle
They usually start as a red/purple tender bump which quickly fills with pus growing larger and more painful until they rupture and drain. They develop a yellow-white tip
What is a carbuncle?
A cluster of boils that form a connected area of infection
What are the 2 types of necrotising fasciitis?
Type 1 : caused by mixed anaerobes and aerobes - most common
Type 2 : strep pyogenes
Who does type 1 necrotising fasciitis most commonly occur in?
Diabetics post-surgery
Risk factors for necrotising fasciitis?
Recent skin trauma, burns or soft tissue infections
Diabetes mellitus, particularly if Tx with SGLT2 inhibitors
IV drug users
Immunosuppression
Most commonly affected site for necrotising fasciitis?
The perineum - known as fournier’s gangrene
What’s is necrotising fasciitis?
A severe, life-threatening infection characterised by rapidly progressing inflammation and necrosis of the fascia and subcutaneous tissue
It spreads along fascial planes, but typically spares the underlying muscle
Features of necrotising fasciitis?
Acute onset pain, swelling and erythema at the affected site
Often presents with rapidly worsening cellulitis with pain out of keeping with physical features
It’s extremely tender with hypoaesthesia to light touch
Skin necrosis, crepitus and gas gangrene are late signs
Fever and tachycardia may occur
Pain is disproportionate to clinical signs
Management of necrotising fasciitis?
Urgent surgical referral debridement
IV antibiotics
Prognosis of necrotising fasciitis?
Average mortality of 20%
What is staphylococcal scalded skin syndrome?
A rare, severe, superficial blistering skin disorder characterised by detachment of the epidermis - triggered by exotoxins release from staph aureus strains
Who gets staphylococcal scalded skin syndrome?
Predominantly in children younger than 5
Peak age 2-3
