Table Of Contents
Overview
| Condition | Description |
|---|---|
| Erysipelas | Superficial infection of the upper layers of the dermis. Raised sharply demarcated edges, rapid spread and onset, and fever early in course. Caused by Streptococcus pyogenes. |
| Cellulitis | Infection that involves the deeper dermis and subcutaneous tissue. Non-purulent and purulent types. Non-purulent is caused by Streptococcus pyogenes and MSSA. Purulent is caused by MSSA and MRSA. |
| Folliculitis | Inflammation of the hair follicle |
| Furuncle | Swollen follicle with purulent material |
| Carbuncle | Furuncles that have merged to form an abscess with draining sinus tracts |
- Principles of treatment
- Topical antibiotics
- Systemic antibiotics (if there are signs of systemic illness or cellulitis)
- Warm compresses
- Analgesia
- Incision and drainage with wound packing (for furuncles, carbuncles, and abscesses)
Impetigo
Impetigo is a highly infectious superficial skin infection caused by Staphylococcus aureus and Streptococcus pyogenes. A skin defect usually precedes infection, and this can be in the form of a scratch or abrasion, or skin condition such as eczema.
Classification
| Classification | Description |
|---|---|
| Bullous impetigo | Due to Staphylococcus aureus which produces an exfoliative exotoxin (exfoliatin) that cleaves desmoglein 1 complexes producing a split between the stratum granulosum and stratum spinosum |
| Non-bullous impetigo | Caused by Staphylococcus aureus and Streptococcus pyogenes |
| Ecythyma | A deeper infection due to Staphylococcus aureus and Streptococcus pyogenes |
- Signs and symptoms
- Bullous impetigo: pustules, blisters → yellowish/brown crust
- Non-bullous impetigo: red sore that discharges pus or fluid → yellowish/brown crust
- Ecthyma may show Lymphadenopathy in the affected area
- Treatment
- Personal hygiene
- Topical antibiotics: mupirocin
- Systemic antibiotics: Flucloxacillin
- Complications
- Post-streptococcal glomerulonephritis
- Rheumatic fever
Folliculitis
Folliculitis is a common infection that is defined as inflammation of the hair follicles. It can be due to infections (bacterial or fungal), inflammation, or blockage of the pores. Most cases are superficial. Deeper cases of folliculitis are harder to treat and may result in scarring. Diagnosis is clinical
- Common locations
- Beard area for adult men (pseudofolliculitis – sterile)
- Legs or arms in people who shave (pseudofolliculitis – sterile)
- Sweaty areas (groin or buttocks)
- Causative organisms
- Staphylococcus aureus (most common)
- Pseudomona (hot tub folliculitis)
- Gram-negative bugs (associated with long-term antibiotic use especially in acne)
- Risk factors for folliculitis
- Sports
- Uncut beard or shaving “against the grain”
- Clothing friction
- Humid environment
- Sweating
- Use of topical steroids
- Immunosuppression
- Skin abrasion
- Carrier of Staphylococcus aureus in the nose
- Occluded skin
- Signs and symptoms
- Rash → pustules → furuncle → carbuncle
- Differentials
- Acne vulgaris
- Herpes simplex
- Keratosis pilaris
- Contact dermatitis
- Milia
- Periorificial dermatitis
- Insect bites
- Investigation
- Pus swab
- Punch biopsy if diagnosis is uncertain
- Workup for diabetes if there are recurrent episodes
- Treatment
- Personal hygiene + use of chlorhexidine body wash
- Topical antibiotics: Mupirocin, Clindamycin
- Systemic antibiotics: flucloxacillin, cephalexin
- Isotretinoin for gram-negative folliculitis
- Incision and drainage for deep infections
Cellulitis
Cellulitis is defined as a bacterial infection of the dermis and subcutaneous tissue. It is often caused by a break in the skin which allows bacteria to enter. It commonly affects the legs and face, though it can infect any area of skin. Infection is often minor, however, in elderly patients and in those with comorbidities there is increased morbidity and mortality. Diagnosis is clinical.
Very common infection. Incidence of 24.6 per 1000 people.
- Risk factors for cellulitis
- Wound to the skin
- Diabetes
- Immunosuppression
- Intravenous drug user
- History of cellulitis
- Elderly
- Obesity
- Fungal infection
- Skin condition e.g. eczema
- Lymphoedema or chronically swollen leg
- Chronic venous insufficiency
- Varicose vein
- Common organisms
- Group A Streptococcus
- Staphylococcus aureus
- Patient History
- Unilateral leg symptoms following a break in the skin
- Signs and symptoms
- Erythema
- Pain
- Swelling
- Warmth
- Site of skin damage (ulcer, wound, bite mark, injection site)
- Systemic symptoms may be present: fever, malaise, nausea, rigors, confusion
- Differentials
- Deep Venous Thrombosis
- Necrotizing Soft Tissue Infection (NSTI)
- Varicose eczema
- Metastatic cancer (Carcinoma erysipeloides)
- Investigations
- CBC: raised WBC count
- CRP: elevated
- Other labs: fasting glucose, lipids, cholesterol
- Blood culture and pus swabs: to identify the causative organism and select antibiotics
- Imaging e.g X-ray: if there is a concern of deeper infection e.g. NSTI or foreign body in situ
- Treatment
- Analgesia
- Elevate the legs
- Tetanus vaccination
- Mild cellulitis: PO Flucloxacillin or Erythromycin or Clarithromycin
- Severe cellulitis: IV Flucloxacillin or Clindamycin
- Indications for hospitalisation
- Significantly unwell with systemic symptoms: tachycardia, tachypnoea, hypotension, vomiting, acute confusion
- Unstable comorbidity e.g. uncontrolled diabetes
- Contaminated wound
- Limb-threatening infection due to vascular compromise
- Sepsis
- Very young or frail
- Immunocompromised
- Gross limb swelling
- Facial cellulitis
- Periorbital cellulitis
- Acute complications
- Abscess
- Sepsis
- Myositis
- Osteomyelitis
- NSTI
- Meningitis
- Post-streptococcal glomerulonephritis
- Chronic complications
- Chronic leg ulcer
- Chronic lymphoedema
