Section 1: Epidemiology and aetiology
Cellulitis and erysipelas are infections of the skin and subcutaneous tissues. Now widely regarded as variants of the same condition, elements of both often coexist within an affected area.
Such superficial soft tissue infections are usually caused by beta-haemolytic streptococci and Staphylococcus aureus. Gram-negative organisms should be suspected following animal bites, in the immunocompromised, the elderly and following hospital admission.
Difficulty of diagnosis
Despite being common these conditions often prove difficult to diagnose and manage. This is well illustrated by a recent Cochrane review from 2010 that struggled to give decisive systematic advice on how to manage these conditions.1
Data from 2009 and 2010 show that within the English NHS 60,146 patients were admitted for cellulitis and erysipelas for an average of 7.1 and 3.8 days respectively.2
Figures from 1998 to 1999 revealed 34,326 admissions for these conditions (cellulitis 33,903 and erysipelas 423) showing an increasing strain on costs and resources over time.2
There is growing evidence that lower limb cellulitis is caused by local risk factors rather than systemic ones, such as diabetes mellitus. A case-control study published in 2008 identified risk factors for the development of lower limb cellulitis as toe web disease, dermatomycosis, local injury, oedema, previous surgery and dermatosis of the leg.3 Animal bites and ulcers can also provide portals of entry for bacteria.4
Once an episode of cellulitis has occurred, patients are at risk of recurrent disease. Recurrence rates of 17-37 per cent are reported thus making cellulitis a persistent problem for a significant proportion of those affected.3
Section 2: Making the diagnosis
Erysipelas, an infection of the dermis and superficial subcutis, often presents on the face (unilaterally) or lower limb but can occur at any site. Streptococcus pyogenes is the most common culprit. Symptoms include pain, increased temperature and erythematous oedema which give erysipelas its most distinctive feature of a well-defined bright red, raised border.
Skin on the face may take on an 'orange peel' appearance and a 'butterfly' distribution can develop. Bullae, ecchymoses and necrosis may form within affected areas. Obese patients are especially at risk of these complications.5
Cellulitis affects deeper structures than erysipelas, including the subcutaneous tissues. Many of the features of erysipelas will be present in cellulitis, such as increased temperature, pain, spreading erythema and swelling, but the margins of infected and unaffected skin are less easily definable. Abscesses or even ulcers can develop. Features of both cellulitis and erysipelas may be seen at the same site of infection. Local and/or regional lymphadenopathy may be present.
Cellulitis on the hand of a 65-year-old woman following a cat bite (Author image)
Often no specific investigations are needed or useful. However, the presence of raised inflammatory markers, such as CRP, ESR and neutrophils, may help if the diagnosis is in doubt, along with other basic investigations, such as renal function, in those who are systemically unwell.
Any weepy or purulent areas should be swabbed and samples sent for microscopy, culture and sensitivities.
|Differential diagnoses to consider|
Section 3: Managing the condition
Initial management is aimed at prompt initiation of appropriate antibiotics. However, a 2010 Cochrane review was unable to define which antibiotics, route or duration were superior.1
Local antibiotics guidelines should be followed but penicillin V with or without flucloxacillin or amoxicillin with clavulanic acid are often used. Clarithromycin or erythromycin should be used in those with penicillin allergy. If a limb is affected, elevation should be advised.
Any underlying dermatoses must be treated aggressively. Usually 10 to 14 days of antibiotics are needed but treatment should be continued until signs of infection have resolved, which may be much longer. This can be difficult to judge when underlying dermatosis has not been adequately treated thus masking any improvements.
Bilateral leg cellulitis
Bilateral leg cellulitis is a rare condition. Compression therapy should be considered in venous/stasis dermatitis along with leg elevation. Active dermatitis should be treated with topical steroids and emollients.
Recurrent infections can occur in lymphoedema. 'Decongestive lymphatic therapy', which consists of an exercise plan, general skin care, multilayered compression bandages and manual lymphatic drainage, may reduce the frequency of recurrent cellulitis.6
Antibiotic prophylaxis (penicillin or erythromycin) can be considered in patients who have two or more episodes per year.
This is mostly seen in children and a low threshold for admission to hospital for parenteral antibiotics and imaging is advised. Warning signs for deep involvement (intraorbital infection or cavernous sinus thrombosis) include failure to improve with antibiotics, pain, proptosis, ophthalmoplegia or oedema preventing full evaluation of eye movements and altered vision.
Obesity alters the skin barrier function, predisposes to poor wound healing and impedes lymphatic flow resulting in lymphoedema.7,8 Obesity also aggravates venous insufficiency, which will exacerbate or initiate venous/stasis dermatitis.
Elephantiasis nostras verruciformis may develop following chronic lymphoedema (see image below).
Elephantiasis nostras verruciformis may develop following chronic lymphoedema (Author image)
Obesity also increases the incidence of other infections, such as candidiasis, folliculitis, tinea cruris and intertrigo, which can be difficult to eradicate due to poor mobility and poor hygiene.7,8
Recurrent purulent infections
Panton-Valentine-Leucocidin toxin is produced by strains of Staph aureus and should be suspected in any purulent skin and soft tissue infection.9 Once isolated, specific antibiotic treatments are advised along with decolonisation which may involve close contacts.
Although rare, this life-threatening condition of the deep fascia necessitates prompt admission to hospital for parenteral antibiotics and surgical debridement.10
The early signs can be very non-specific but features include severe local pain and tenderness over areas of erythematous, mottled or blistering necrotic skin.
Signs may rapidly develop with gas demonstrable in the tissues (crepitus) and systemic upset.
Referral is required in those who are systemically unwell with signs of septicaemia or septic shock. Failure to improve with oral antibiotics, the presence of comorbidities and complications are also indications for admission.
Each case is different and management strategies must reflect this. Referral to a lymphoedema clinic, vascular clinic, podiatrist, diabetic foot clinic or dermatologist may be appropriate depending on the underlying problems.
Section 4: Prognosis
Prognosis depends on many factors, such as severity of initial infection and any complications and comorbidities which may hinder recovery.
Cellulitis and erysipelas can become a recurrent, chronic problem and identifying underlying risk factors is essential. If recurrence at the same site is a problem despite prevention strategies, long-term low-dose penicillin can be tried for a couple of years.
Early patient-initiated treatment can also be tried to assess if this impacts on frequency and severity of infections.
After starting antibiotics and managing in primary care, review should be arranged within 48 hours to assess response. Once the infection has cleared, no matter where the patient was managed, a review should be arranged to assess and address risk factors to prevent the development of further episodes.
Section 5: Case study
Our dermatology team reviewed a 65-year-old woman who had seen her GP 14 days previously with fever and vomiting and had failed to respond to a course of antibiotics.
On admission she had been diagnosed with bilateral lower leg cellulitis and initial blood tests revealed a raised WCC of 18 (4-11x109/L), neutrophils 12 (1.9-7.5x109/L), CRP of 157 (0-10mg/L) and ESR of 80mm/hr.
After 14 days of IV antibiotics (benzylpenicillin and flucloxacillin) she felt systemically much better and her inflammatory markers were settling; however, her legs remained red, sore and swollen.
On examination there was bilateral, dry, scaly, blanching and tender erythema extending up to the knees with bilateral pitting oedema, haemosiderin deposition and venous flare.
Some blistering and haemorrhage had occurred around the ankles and was now crusting over. She admitted to having had varicose vein surgery 10 years before. Multiple courses of oral antibiotics had failed to resolve the problem.
Venous/stasis dermatitis complicated by cellulitis and erysipelas was diagnosed. The patient was advised to continue treatment with oral antibiotics as an outpatient. The patient was advised to keep the legs elevated, to apply topical moderate potency steroids twice a day to red areas and to use regular emollients containing antimicrobials (benzalkonium chloride and chlorhexidine), which can also be used as soap substitutes.
Two weeks later at review, the antibiotics were stopped because the erythema and pain had improved. Topical treatments were continued.
One month later, topical steroids were being used just twice a week and the lower legs remained free of active dermatitis or cellulitis.
We advised lower leg compression therapy and ongoing skin care with topical steroids as required and regular emollients to prevent further flares.
Section 6: Evidence base
- Kilburn SA, Featherstone P, Higgins B et al. Interventions for cellulitis and erysipelas. Cochrane Database Syst Rev 2010; (6): CD004299.
This review was unable to identify the best treatment for cellulitis and erysipelas.
- CREST. Guidelines on the management of cellulitis in adults. 2005.
- The British Lymphology Society. Consensus document on the management of cellulitis in lymphoedema. 2010.
Available from: www.thebls.com/docs/consensus.pdf
- Wolff K, Katz SI, Goldsmith LA et al. Fitzpatrick's dermatology in general medicine (seventh edition). McGraw-Hill Medical, 2007.
Chapter 179 covers cellulitis, erysipelas and other soft tissue infections.
This topic is covered in the GP curriculum in statement 15.10 Skin problems
- The British Lymphology Society - www.thebls.com
- The Lymphoedema Support Network - www.lymphoedema.org
Both of these websites provide advice for patients and doctors on managing lymphoedema, with specific guidelines on cellulitis in lymphoedema.
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1. Kilburn SA, Featherstone P, Higgins B et al. Interventions for cellulitis and erysipelas. Cochrane Database Syst Rev 2010; (6): CD004299.
2. NHS. Hospital Episode Statistics. www.hesonline.nhs.uk
3. Halpern J, Holder R, Langford NJ. Ethnicity and other risk factors for acute lower limb cellulitis: a UK-based prospective case-control study. Br J Dermatol 2008; 158: 1288-92.
4. Wolff K, Katz SI, Goldsmith LA et al. Fitzpatrick's dermatology in general medicine (seventh edition) McGraw-Hill Medical, 2007.
5. Krasagakis K, Samonis G, Valachis A et al. Local complications of erysipelas: a study of associated risk factors. Clin Exp Dermatol 2010; 36: 351-4.
6. The British Lymphology Society. Consensus document on the management of cellulitis in lymphoedema. 2010.
7. Shipman AR, Millington GWM. Obesity and the skin. Br J Dermatol 2011: 165; 743-50.
8. Yosipovitch G, DeVore A, Dawn A. Obesity and the skin: skin physiology and skin manifestations of obesity. J Am Acad Dermatol 2007; 56; 901-16.
9. Ellington MJ, Ganner M, Smith IM et al. Panton-Valentine Leucocidin-related disease in England and Wales. Clin Microbiol Infect 2010; 16: 86-8.
10. Health Protection Agency. General information - necrotising fasciitis. www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/NecrotisingFasciit is/GeneralInformationNecrotising Fasciitis/