Cellulitis results in high morbidity and severe financial costs to healthcare providers worldwide. Hospital visits due to the infection are increasing in Australia, the United Kingdom and the United States, with average lengths of stay of up to a week. This clinical review, published in the British Medical Journal, summarises recent evidence in the diagnosis and management of the condition.
The majority of cellulitis cases are caused by Streptococcus pyogenes or Staphylococcus aureus, with a recent review finding that S aureus caused more than half of all cellulitis cases; the two organisms together accounting for 78% of cases reviewed. Antibiotic resistance is on the rise, with studies showing a majority of S aureus infections in the US - up to 74% in some hospitals - are now CA-MSRA.
As cellulitis often presents with similar symptoms to other conditions – 28% of cellulitis patients in a recent study had been incorrectly diagnosed – further investigations are often recommended to aid diagnosis. This review finds neither blood investigations nor blood cultures to be clinically useful for cellulitis diagnosis, with available evidence suggesting wound swabs to be the most accurate microbiological diagnostic tool. Imaging has also been shown to be useful in cellulitis diagnosis and management, with ultrasound able to detect occult abscesses and thus ensure that drainage is used (and is only used) when necessary. Magnetic resonance imaging can be used to confirm suspected cases of necrotising fasciitis.
A recent Cochrane review analysed 25 randomised controlled trials of cellulitis interventions but drew no definitive conclusions on the optimal antibiotics, duration or route of administration. However, national guidelines in the US and the UK recommend treatment of typical cellulitis with amoxicillin or flucloxacillin. The rise in CA-MRSA should be taken into account, however; the Infectious Diseases Society of America now recommends that patients with pus-forming cellulitis be treated with antibiotics that target CA-MRSA. Of these, doxycycline and minocycline have been shown to be effective in 95% of patients with CA-MSRA, with clindamycin also effective, but possibly problematic, and linezolid and vancomycin effective for patients requiring hospitalisation.
It is possible that many more cellulitis patients could be treated outside of hospitals. The new Dundee classification system provides an alternative to the widely-used Eron classification system for cellulitis diagnosis and treatment. If assessed under the Dundee criteria, 70% of patients that would be hospitalised under the Eron system would be managed instead as outpatients. Indeed, a recent Scottish study found that 43% of patients hospitalised for cellulitis were overtreated and could have been managed as outpatients on oral antibiotics.
The Cochrane review mentioned above highlighted the need for further evaluation of oral versus intravenous antibiotics and the efficiency of outpatient parenteral antibiotic therapy (OPAT). One study of 344 cellulitis patient treated by a UK OPAT service found that 87% of patients were cured, with a readmission rate of only 6.3%. Conservative estimates costed OPAT at 41% of inpatient costs, and this study's authors concluded that clinicians should use OPAT where available.
Phoenix G, Das S, Joshi M, Diagnosis and management of cellulitis, British Medical Journal. 2012; 345:38-42: e4955.
Article taken from HITH Journal Club, Issue No. 17 April 2014
