Prophylactic Antibiotics for the Prevention of Cellulitis (Erysipelas) of the Leg

Results of the U.K. Dermatology Clinical Trials Network's PATCH II Trial

U.K. Dermatology Clinical Trials Network's PATCH Trial Team


The British Journal of Dermatology. 2012;166(1):169-178. 

In This Article

Abstract and Introduction


Background Cellulitis (erysipelas) of the leg is a common, painful infection of the skin and underlying tissue. Repeat episodes are frequent, cause significant morbidity and result in high health service costs.
Objectives To assess whether prophylactic antibiotics prescribed after an episode of cellulitis of the leg can prevent further episodes.
Methods Double-blind, randomized controlled trial including patients recently treated for an episode of leg cellulitis. Recruitment took place in 20 hospitals. Randomization was by computer-generated code, and treatments allocated by post from a central pharmacy. Participants were enrolled for a maximum of 3 years and received their randomized treatment for the first 6 months of this period.
Results Participants (n = 123) were randomized (31% of target due to slow recruitment). The majority (79%) had suffered one episode of cellulitis on entry into the study. The primary outcome of time to recurrence of cellulitis included all randomized participants and was blinded to treatment allocation. The hazard ratio (HR) showed that treatment with penicillin reduced the risk of recurrence by 47% [HR 0·53, 95% confidence interval (CI) 0·26–1·07, P = 0·08]. In the penicillin V group 12/60 (20%) had a repeat episode compared with 21/63 (33%) in the placebo group. This equates to a number needed to treat (NNT) of eight participants in order to prevent one repeat episode of cellulitis [95% CI NNT(harm) 48 to ∞ to NNT(benefit) 3]. We found no difference between the two groups in the number of participants with oedema, ulceration or related adverse events.
Conclusions Although this trial was limited by slow recruitment, and the result failed to achieve statistical significance, it provides the best evidence available to date for the prevention of recurrence of this debilitating condition.


Cellulitis (also known as erysipelas) of the leg is an acute, painful and potentially serious infection of the skin and subcutaneous tissue associated with significant morbidity[1,2] and health costs (cost of inpatient admission alone was £96 million in 2009/2010).[3–5] It is usually due to streptococcal infection.6 Risk factors for cellulitis of the leg include previous episode(s) of cellulitis; lymphoedema; toe web maceration; obesity and diabetes.[7–9] Many patients have recurrent episodes (30–50%),[10,11] which can lead to subsequent lymphoedema and ulceration.

Evidence for the use of prophylactic antibiotics to prevent further episodes is very limited. Three small randomized controlled trials (RCTs) hint at possible benefit (with 16, 40 and 58 participants, respectively).[12–14] Some clinical guidelines recommend long-term antibiotic prophylaxis for patients with predisposing conditions.[15,16] However, such recommendations are based largely on empirical evidence and clinical opinion is mixed.17

Two trials of cellulitis prophylaxis have been initiated by the U.K. Dermatology Clinical Trials Network. PATCH I has recruited to target and is due to report in 2012, and will assess the impact of 12 months of prophylactic phenoxymethylpenicillin (penicillin V) in patients with recurrent cellulitis (at least two previous episodes). The PATCH II trial, reported here, assesses whether 6 months of prophylaxis with penicillin V is effective in reducing repeat episodes of cellulitis of the leg in patients who have had one or more episodes.


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