Cellulitis

Question 1

Define cellulitis

Answer 1

acute spreading infection of the skin with visually indistinct borders that principally involves the dermis and SC tissue

Question 2

Define erysipelas

Answer 2

distinct form of superficial cellulitis with notable lymphatic involvement - raised and sharply demarcated from uninvolved skin

Question 3

What is the aetiology of cellulitis

Answer 3

Disruptions in the cutaneous barrier → micro-organisms gain entry into the dermal and SC tissue

Beta-haemolytic streptotocci (pyogenes)
Staph aureus
Pseudomonas (hot tubs, sponges)
Vibrio vulnificus (salt water)
Aeromonas hydrophila (fresh water)
Streptococcus pneumoniae, Haemophilus influenzae, gram negative bacilli, and anaerobes (injury, burns, and other co‐existing diseases e.g. people who are immunocompromised, have diabetes, cancer, or malnutrition)

Question 4

What are the risk factors for cellulitis

Answer 4

Preceding event that caused a break in the skin e.g. trauma (bite, burn, laceration)
Diabetes → ulceration
Venous insufficiency → ulceration
Eczema
Oedema and lymphoedema
Obesity
Pregnancy
Previous episodes of cellulitis
Toe-web abnormalities

Question 5

What are the symptoms of cellulitis

Answer 5

Cellulitis: Acute, onset of red, painful, hot, swollen skin
Erysipelas: Well-demarcated, bright-red raised skin

Rash: red, painful, warm, swollen
Swelling
Blistering
Bullae
Bleeding → petechiae or ecchymosis, blisters, cutaneous haemorrhage
Fever, malaise, nausea, rigors

Question 6

What are the differentials for cellulitis

Answer 6

Erysipelas
Chronic venous insufficiency
DVT
Septic arthritis
Acute gout
Rupture Baker’s cyst
Thrombophlebitis
Cutaneous abscess

Question 7

What are the signs of cellulitis and erysipelas on examination

Answer 7

Obs: Fever
Skin:
- red, painful, hot, swollen skin
- Lower limbs, unilateral
- Well-demarcated border that can be marked with pen
- Rapidly spreading
± blistering
± petechiae/ecchymoses
± peau d’orange (orange-peel appearance due to oedema around hair follicles)
± lymphadenopathy, lymphangitis

Erysipelas = well-demarcated RAISED skin

Question 8

What investigations should be done for cellulitis

Answer 8

Bedside: wound swab for culture (wounds only), nose/throat swabs
Bloods: blood cultures, FBC, ESR/CRP
Other: US ± aspiration (if abscess present), skin biopsy (if doubts), plain X-ray (?osteomyelitis, gas gangrene)

Question 9

What are the classifications of cellulitis

Answer 9

Eron classification
Class I — no signs of systemic toxicity + no uncontrolled comorbidities.
Class II — either systemically unwell or systemically well but with a comorbidity (e.g. peripheral arterial disease, chronic venous insufficiency, or morbid obesity) which may complicate or delay resolution of infection.
Class III — significant systemic upset, e.g. acute confusion, tachycardia, tachypnoea, hypotension, or unstable comorbidities that may interfere with a response to treatment, or a limb-threatening infection due to vascular compromise.
Class IV — sepsis or a severe life-threatening infection, such as necrotizing fasciitis.

Question 10

What is the management for cellulitis

Answer 10

?sepsis → admit

1. Draw around the extend of infection
2. High dose oral Abx e.g. oral flucloxacillin 4x daily (allergy → clarithromycin, near nose/eyes → co-amoxiclav)
3. Advice:
   - Paracetamol/ibuprofen
   - Adequate fluids
   - Elevate affected area
   - Avoid compression
4. Safety net

+ follow up after 3 days

Question 11

What features of cellulitis may require admission

Answer 11

Class III or IV eron
Severe or rapidly deteriorating
Young <1yo or frail
Immunocompromise
Facial cellulitis
Orbital or peri-orbital

Question 12

What are the complications for cellulitis

Answer 12

Sepsis
Chronic oedema due to damage to draining lymphatics
Abscess
Necrotising fasciitis
Peri-orbital cellulitis
Myositis
Recurrence

Question 13

What is the prognosis for cellulitis

Answer 13

Excellent
Resolves with therapy, major sequelae uncommon
May recur (8-20%) or leave residual lymphatic damage