Table of Contents
Overview
Furuncles and carbuncles are deep skin infections involving hair follicles. They are typically caused by Staphylococcus aureus, including methicillin-resistant strains (MRSA), and often require medical treatment including drainage and antibiotics. They represent a progression from superficial folliculitis to deeper, more painful abscesses.
Definitions
- Furuncle (Boil): A painful, pus-filled nodule originating from a hair follicle, extending into the dermis and subcutaneous tissue.
- Carbuncle: A coalescence of multiple furuncles forming a larger, deeper abscess, often with multiple drainage points.
Aetiology
- Causative Organism:
- Staphylococcus aureus (most common)
- MRSA increasingly identified in community and hospital settings
- Risk Factors:
- Friction/trauma (e.g. shaving)
- Poor hygiene
- Occlusive clothing
- Diabetes mellitus
- Immunosuppression
- Colonisation with S. aureus
Pathophysiology
- Disruption of hair follicle integrity → Entry of bacteria
- Infection progresses deeper into dermis and subcutaneous fat
- Localized inflammatory response → Accumulation of pus
- Furuncles may expand or coalesce into carbuncles, especially in immunocompromised individuals
Clinical Features
| Feature | Furuncle (Boil) | Carbuncle |
|---|---|---|
| Appearance | Tender red nodule | Cluster of tender nodules |
| Centre | May develop central yellow/white point | Multiple drainage points |
| Pain | Common and can be intense | Often more painful and extensive |
| Systemic symptoms | Rare | May include fever, malaise |
| Location | Face, neck, axillae, buttocks, thighs | Commonly on the back or neck |
2. Public Domain: https://www.healthdirect.gov.au/boils
Differential Diagnoses
- Epidermal cyst (if no drainage)
- Cellulitis
- Acne nodules
- Hidradenitis suppurativa
- Infected insect bites
Investigations (if recurrent or severe)
- Swab for MCS (microscopy, culture, and sensitivity)
- Blood glucose (screen for diabetes)
- MRSA screening
- Consider immune work-up if recurrent
Management
General Measures
- Warm compresses: Promote drainage and comfort
- Hygiene education: Avoid sharing razors, towels
- Topical antiseptics: Chlorhexidine wash
Medical Treatment
- Antibiotics (oral or IV depending on severity):
- Flucloxacillin (1st line)
- Clindamycin or doxycycline (if penicillin-allergic or MRSA suspected)
- Incision & drainage (I&D):
- For fluctuant, draining or large lesions
- Should be done under sterile technique
For recurrent furunculosis:
- Nasal mupirocin (to eliminate S. aureus carriage)
- Regular antiseptic body wash
- Treat close contacts if colonised
Complications
- Cellulitis
- Abscess formation
- Scarring or pigmentation changes
- Recurrent furunculosis
- Sepsis (rare, more likely with carbuncles)
Summary – Furuncles & Carbuncles
Furuncles and carbuncles are deep, often painful infections arising from hair follicles, most commonly caused by Staphylococcus aureus. Treatment typically includes antibiotics and drainage. Preventative hygiene and decolonisation strategies are crucial in recurrent cases. Visit Skin & Dermatology for related infections.