We welcome the review of cellulitis diagnosis and management by Phoenix et al.(1) In addition to the comments made by our infection colleagues we would like to the highlight some of the key issues faced by clinicians who manage this infection regularly and several recent changes in practice that the authors have not mentioned.
The number of hospital admissions in England in 2008/9 was 14,152,692, of which 82,113 were for cellulitis. In addition hospital visits for abscesses and cellulitis in the paper quoted increased from 17.3 to 32.5 visits per 1000 population, a ten fold difference to that quoted by Phoenix et al.(1,2)
Multiple studies have demonstrated that streptococci rather than staphylococci are the commonest cause, in contrast to the one review quoted in the paper. (3,4,5,6) The table in the review mentions some of the rarer pathogens and associated risk factors. It is important to say that even in the context of these risk factors streptococci and staphylococci are usually the major culprits. Identification of an organism is often problematic as blood cultures are often negative and skin biopsies are confounded by skin colonisation. Empiric treatment should still treat the commonest organisms.
Community-acquired (CA)-MRSA has not emerged in the UK and Europe, unlike the US, (7) as a significant pathogen and empiric treatment should remain Flucloxacillin or other similar beta-lactam antibiotics at present in these countries.
Of particular concern in the review was the management of necrotising fascitis. This is commonly caused by beta–haemolytic streptococci,usually Group A streptococci; anaerobes and Gram-negative organisms are also important, particularly if the site is below the umbilicus. Diagnosis is clinical and surgical debridement should not be delayed by imaging as the authors suggest. (8,9)
Upper limb, torso and facial cellulitis have very different aetiologies to that of the lower limb and are often more serious. The management of these varies considerably and involvement of a specialist should be sought early.
The provision of outpatient parenteral antimicrobial therapy (OPAT) for the follow-up of inpatient care has been well established.(10) However, from April 2011 provision of an ambulatory care pathway for cellulitis became one of the clinical quality indicators for all Emergency Departments in acute trusts (11).
This expects acute hospital trusts to develop and implement pathways for patients who have failed on oral antibiotics or where the infection is deemed more severe to access intravenous antibiotics and specialist input without being admitted to hospital. This is a key change in approach to managing cellulitis. In our trust the pathway has been running for 16 months. There are clear exclusion criteria relating to co-morbidity, signs of systemic sepsis, and site of cellulitis, those patients are admitted. Patients on the pathway receive one to three days of intravenous therapy with ceftriaxone and are reviewed daily by an Emergency Physician. Once stabilised the patients then complete the treatment with appropriate oral agents. The pathway was developed by the Emergency Department and Infectious Diseases teams. One hundred and thirty one patients were treated on the pathway over one year. The age range was 18-91 years. The median treatment course with once daily ceftriaxone was 2 days (range 1-6 days). Sixteen (12.1%) patients subsequently required hospital admission for a median of 3 days (range 1-7 days). Fifteen (93.4%) of these patients were admitted as they had not responded appropriately to ambulatory care pathway - with progressive infection (12), development of bursitis (2), and the development of abscess (1). Only one other patient was admitted in the subsequent 28 days with a fractured ankle.

Based on this data the introduction of a multidisciplinary pathway with access to Infectious Diseases physicians, and other experts can safely maintain many patients on an ambulatory care pathway. We estimate that we have saved the hospital more than £150,000 in in-patient bed stays based on days treated on the ambulatory care pathway.
Ambulatory care pathways, with increased input from infection doctors and other specialist services are all set to improve the experience of patients with cellulitis. It is important that clinicians are aware of all the options available for management of this challenging, common condition.

1) Phoenix G, Das S, Joshi M. Diagnosis and management of cellulitis. BMJ 2012;345:e4955.
2.) Hersh AL, Chambers HF, Mseli JH, Gonzales R. National trends in ambulatory visits and antibiotic prescribing for skin and soft tissue infections. Arch Intern Med 2008; 168:1585-91.
3.)Peralta G, Padrón E, Roiz MP, De Benito I, Garrido JC, Talledo F, Rodríguez-Lera MJ, Ansorena L, Sánchez MB.Risk factors for bacteremia in patients with limb cellulitis.Eur J Clin Microbiol Infect Dis. 2006;25(10):619.

4.)Bernard P, Bedane C, Mounier M, Denis F, Catanzano G, Bonnetblanc JM. Streptococcal cause of erysipelas and cellulitis in adults. A microbiologic study using a direct immunofluorescence technique.
Arch Dermatol. 1989;125(6):779.

5.)Semel JD, Goldin H. Association of athlete's foot with cellulitis of the lower extremities: diagnostic value of bacterial cultures of ipsilateral interdigital space samples. Clin Infect Dis. 1996;23(5):1162.

6.)Chira S, Miller LG. Staphylococcus aureus is the most common identified cause of cellulitis: A systematic review. Epidemiol Infect 2010; 138:313-7.
7.)Kock R, et al. Methicillin-resistant Staphylococcus aureus (MRSA): burden of disease and control challenges in Europe. Euro Surveill. 2010 Oct 14;15(41): 19688

8.)Brook I, Frazier EH.Clinical and microbiological features of necrotizing fasciitis.J Clin Microbiol. 1995;33(9):2382.

9.)Wong CH, Chang HC, Pasupathy S, Khin LW, Tan JL, Low CO Necrotizing fasciitis: clinical presentation, microbiology, and determinants of mortality.J Bone Joint Surg Am. 2003;85-A(8):1454.

10.)Barr DA, Semple L, Seaton A. Outpatient parenteral antimicrobial prescribing in a teachin hospital- based practice: A retrospective cohort study describing expererience and evolution over 10 years. Int J of Antimicrob Agents 39 (2012) 407-413
11.)http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/@dh/@en/@ps/documents/digitalasset/dh_122892.pdf

Competing interests: None declared