Passive treatment

• Passive treatment (hygiene measures alone) is not recommended, even for small, localized lesions. Although placebo-controlled trials have shown that untreated impetigo usually resolves in about 2–3 weeks [Koning et al, 2003], topical treatment is effective and has few adverse effects. In addition, untreated impetigo is highly contagious and there is a risk it may become generalized.

Topical treatment

• There is good evidence from several placebo-controlled and comparative randomized controlled trials (RCTs) that topical antibiotics are effective in the treatment of localized non-bullous impetigo [George and Rubin, 2003; Koning et al, 2003].
• Fusidic acid is recommended first-line. It is effective against Staphylococcus aureus and Streptococcus pyogenes and is licensed for the treatment of impetigo [ABPI Medicines Compendium, 2001]. It has been shown in comparative RCTs to be as effective as mupirocin and retapamulin.
• Mupirocin should be reserved for the treatment of impetigo known to be caused by meticillin-resistant Staphylococcus aureus (MRSA) because of concerns over bacterial resistance. This is in line with recommendations from the Health Protection Agency [HPA and Association of Medical Microbiologists, 2008] and the British National Formulary [BNF 56, 2008].
• Retapamulin is a newer topical antibiotic that has been shown, in a comparative RCT, to be equivalent in efficacy to fusidic acid [Oranje et al, 2007]. However, it is a black triangle drug (undergoing post-marketing surveillance), and is likely to be more expensive than fusidic acid without offering additional clinical benefit. On this basis, some experts recommend it should be reserved as a second-line treatment [DTB, 2008].
• Topical antiseptics are not recommended for the treatment of impetigo, although some specialists advocate the use of hydrogen peroxide cream in some instances. There is limited evidence from a meta-analysis of two RCTs that topical antiseptics are not as effective as topical antibiotics. They can also cause skin reactions, and antiseptics that have an alcoholic base can exacerbate dry and fissured skin [Watkins, 2005].
• Removing crusts: there is insufficient evidence from controlled trials to show whether removing the crust from lesions before application of a topical antibiotic improves their efficacy [DTB, 2008]. However, it is believed by some experts that removal of the crust will allow the antibiotic to come into direct contact with the pathogens rather than being wasted on inert, dry, exfoliating skin [Watkins, 2005]. Removal of scabs formed during the healing process is not recommended as it is likely to cause pain, bleeding, and scarring.

Oral antibiotics

• The evidence to support the use of oral antibiotics to treat impetigo is limited due to a lack of adequate placebo-controlled trials, although for localized impetigo, comparative RCTs have shown they are probably not as effective as topical antibiotics [George and Rubin, 2003; Koning et al, 2003]. However, for more extensive impetigo, or for impetigo causing systemic symptoms, oral antibiotics are the most practical option. There is little evidence on the treatment of bullous impetigo, but oral antibiotics are thought to be a reasonable option [DTB, 2007].
• Flucloxacillin is recommended as first-line treatment for extensive impetigo [HPA and Association of Medical Microbiologists, 2008]. Although there is a lack of evidence from RCTs to prove the efficacy of flucloxacillin, it is known to be effective against Gram-positive organisms, including beta-lactamase producing Staphylococcus aureus [ABPI Medicines Compendium, 2008a], and it demonstrates suitable pharmacokinetics, with good diffusion into skin and soft tissues [Finch et al, 2003].
• Erythromycin is a macrolide antibiotic with a broad spectrum of activity, including most staphylococcal and streptococcal species [Finch et al, 2003]. It has been studied relatively extensively in comparative RCTs, and been found to be superior to penicillin, and equivalent to most other antibiotics [Koning et al, 2003].
• Clarithromycin is recommended as an alternative macrolide to erythromycin. It is generally considered to cause less adverse effects than erythromycin [DTB, 1991] and although this advantage is mainly theoretical, there are some limited data from RCTs to corroborate this [Aronson, 2006]. In addition, it only requires twice-daily dosing, an important consideration for children of school age.

Follow-up

• Most controlled trials have shown positive results from topical and oral antibiotics after 1 week [George and Rubin, 2003; Koning et al, 2003] making routine follow-up unnecessary.