Public Health England and the British Infection Association recommend that topical antibiotics are reserved only for treatment of very localised lesions because fusidic acid is an antibiotic that is also used systemically. There are concerns that widespread use of topical fusidic acid will lead to increased resistance, rendering systemic fusidic acid (used for severe staphylococcal infections such as osteomyelitis or systemic MRSA) ineffective. If a topical antibiotic is used, a short course (such as 5 days) reduces exposure and the risk of resistance. Since few agents are effective against MRSA, mupirocin should be reserved for such cases.

Public Health England and the British Infection Association recommend flucloxacillin for first-line treatment of impetigo because it is a narrow-spectrum antibiotic that is effective against Gram positive organisms, including beta-lactamase producing Staphylococcus aureus, and it demonstrates suitable pharmacokinetics, with good diffusion into skin and soft tissues. Clarithromycin is recommended for people with penicillin allergy because it is also active against most staphylococcal and streptococcal species.

Koning S, Verhagen AP, van Suijlekom-Smit LWA, Morris AD, Butler C, van der Wouden JC. Interventions for impetigo. Cochrane Database of Systematic Reviews. 2003. Issue 2.
http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD003261/frame.html Accessed 23.09.14. RATIONALE: Many RCTs identified by this Cochrane review were of poor methodological quality. Pooled data from four RCTs found no difference in cure rates between topical mupirocin and topical fusidic acid (OR 1.22, 95% CI 0.69 to 2.16). Most RCTs that compared topical compared with oral antibiotics used mupirocin. However, mupirocin is reserved for MRSA and should not be used first-line for impetigo. Topical fusidic acid was significantly better than oral erythromycin in one study, but no difference was seen between fusidic acid and oral cefuroxime in a different arm of the same study. Topical bacitracin was significantly worse than oral cefalexin in one small study, but there was no difference between bacitracin and erythromycin or penicillin in two other studies. The results of one non-blinded RCT suggested that topical fusidic acid was more effective than topical hydrogen peroxide, but this did not quite reach statistical significance.

Public Health England and the British Infection Association recommend that topical retapamulin or polymixin are reserved for use in areas where there are rising rates of resistance to fusidic acid. Polymixin (contains bacitracin) has less robust RCT evidence than fusidic acid. Although topical retapamulin has been demonstrated to be non-inferior to topical fusidic acid for the treatment of impetigo in one randomized controlled trial, it is more expensive and there are less safety data available (it is a black triangle drug).

Denton M, O’Connell B, Bernard P, Jarlier V, Williams Z, Santerre Henriksen A. The EPISA study: antimicrobial susceptibility of Staphylococcus aureus causing primary or secondary skin and soft tissue infections in the community in France, the UK, and Ireland. J Antimicrob Chemother 2008;61:586-588. RATIONALE: Of S. aureus isolates from the UK, only 75.6% were susceptible to fusidic acid. A diagnosis of impetigo was associated with reduced fusidic acid susceptibility.

The POCAST project is funded by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Healthcare Associated Infections and Antimicrobial Resistance at Imperial College London and by the Imperial College Healthcare Charity (Grant Ref No:7006/P36U).