Cellulitis

Causes

1. Most cases due either to Gp A Streptococci (GAS) or staphylococci.
2. Rarely gram negative organisms in immunocompromised patients or diabetes
3. Specific risk of pseudomonas from jacuzzis
4. Cellulitis around surgical wounds with crepitus should raise suspicion of multimicrobial.
5. Need to search for portal of entry eg venous leg ulcers, athlete’s foot (look for cracks between toes).
6. Other risk factors include leg oedema, lymphoedema, obesity (which may cause lymphoedema) and IV drug use (look for sinus in groins).
7. Recurrence is most likely in patients with chronic lymphoedema

Clinical Presentation

1. Typically acute onset of red, painful, hot, swollen and tender skin, with fever malaise, nausea, shivering and rigors. There is often a well demarcated edge that can be marked with a pen. Lymphatic streaking and regional lymphadenopathy may be present.
2. If the infection is severe the person may be systemically unwell with tachycardia, tachypnoea, hypotension and confusion even before onset of skin changes.
3. Necrotising fasciitis is a fulminant, potentially life threatening, rapidly spreading infection characterised by extensive necrosis and gangrene of skin and underlying structures (requires urgent surgical referral).
4. Erysipelas is term used when infection superficial with well defined edge. Commonly facial and due to GAS (distinction from cellulitis somewhat academic).
5. Bilateral lower extremity cellulitis almost never happens, so resist making this diagnosis in patients with bilateral painful red legs with no fever, leukocytosis, lymphadenopathy, or streaking.

Other Causes of Unilateral Redness or Swelling

1. DVT – though this is usually characterized by pain and swelling without significant redness
2. Acute gout – confusion may arise if the skin around the joint is inflamed (gout cellulitis)
3. Ruptured Baker’s cyst – may cause unilateral calf swelling, albeit without significant redness.
4. Thrombophlebitis – redness with inflammation and pain in the line of a superficial vein
5. . Extravasation- consider this if the patient has had Systemic Anti-Cancer Treatment (SACT) administered near the site of inflammation. If suspected, please seek urgent Oncology advice and follow these guidelines (Section 6, pp39-54) – Lothian Online Oncology Quality System (OOQS) Extravasation Guidance 

Chronic Conditions usually Bilateral which if Worse on One Side may look like Cellulitis

1. Chronic venous insufficiency – this is the commonest misdiagnosis. Patient may have a red, hot, swollen leg, often with haemosiderin staining, in the absence of fever, leukocytosis, lymphadenopathy, or streaking.
2. Severe oedema with blistering – though leg is not usually red.
3. Lymphoedema.
4. Other conditions that may cause localised redness and sometimes be mistaken for cellulitis include: cutaneous small vessel vasculitis, Erythema Nodosum (painful nodules on shins in patients with TB or sarcoidosis) and Pyoderma Gangrenosum (deep necrotic ulcers in patients with inflammatory bowel disease or RA).

Choice of Antibiotic

1. Please refer to Cellulitis section in NHSD&G Antibiotic Guidelines Poster – Adults in Secondary Care, OR NHSD&G Antibiotic Guidelines (Full) – Adults in Secondary Care

Other Aspects of Treatment

1. Recent evidence supports shorter courses of antibiotics. 7 days recommended.
2. IVOS if clinical improvement and temp <38º for 48 hours but delay if lymphoedema, cardiac/liver/renal failure or diabetes
3. Keep an eye on renal function if using flucloxacillin 2g IV dose. Reduce dose if creatinine starts to increase. Use a 1g dose in smaller frail patients or those with existing CKD.
4. May be suitable for OPAT – Click Here for Link to OPAT Cellulitis Pathway [pdf] and to the OPAT Referral Form
5. Athlete’s foot often present and should be treated with miconazole 2% cream applied twice daily and continued for two weeks after skin has healed.
6. Keep leg elevated when sitting but mobilise as comfort allows.

Patient Information

1. Cellulitis – What You Need to Know – Patient Information Leaflet [pdf]

Links

1. Triage of skin or soft tissue infection affecting upper or lower limb(s) or face for same day discharge in ED or CAU [pdf]

Content by Susan Coyle