Rationales

The recommendations in this guideline are based on the evidence identified and the experience of the committee.

Treatment

Why the committee made the recommendations

Recommendations 1.1.1 to 1.1.7

The committee agreed, based on their experience, that it is important to optimally manage underlying eczema in people who present with a suspected secondary bacterial infection, for example, with emollients and topical corticosteroids. They also agreed that it is important to optimally manage flares in all people with stepped topical corticosteroids; for managing eczema in children under 12, there are recommendations on the use of stepped corticosteroids in the NICE guideline on atopic eczema in under 12s. The committee also noted that information on optimally managing atopic eczema in all people (aged over 1 month) was available in NICE's clinical knowledge summary on atopic eczema.

The committee agreed with the symptoms and signs of secondary bacterial infection of eczema in the NICE guideline on atopic eczema in under 12s. The committee recognised that, in practice, it can be difficult to tell the difference between a non-infected flare of eczema and eczema that has become infected. There may be no bacterial infection even if there are classic signs of infection such as weeping and crusts. A more useful indicator of infection may be that a person feels systemically unwell with fever or malaise. However, without definitive diagnostic criteria, diagnosing secondary bacterial infection of eczema will be based on history taking and the person's (or parent's or carer's) knowledge of their own condition. The committee also discussed that healthcare professionals should be aware that redness, one of the signs of infection, may be less visible on darker skin tones.

The committee agreed that skin swabs for microbiological testing should not routinely be taken at the initial presentation of a suspected secondary bacterial infection of eczema. The skin of people with eczema is often heavily colonised with Staphylococcus aureus (S. aureus) bacteria, and bacterial growth from a skin swab is likely regardless of infection status. Taking skin swabs from everyone with a suspected infection could lead to inappropriate antibiotic prescribing. If the eczema is clinically infected, the most likely causative organisms are S. aureus or Streptococcus pyogenes (S. pyogenes), so empirical treatment with topical fusidic acid or oral flucloxacillin would be effective.

The evidence suggested that using topical or oral antibiotics in addition to topical corticosteroids offered little benefit over using topical corticosteroids alone in people with a suspected secondary bacterial infection of eczema. The committee agreed that the evidence is limited because there are no definitive criteria for diagnosing a secondary bacterial infection. The committee went on to discuss that the available evidence was in children (or it was unclear whether the population included adults); they noted that the results from the evidence in children could be extrapolated to adults because the response to treatment would be sufficiently similar across different age groups. The committee also notes that trials have often excluded people with a severe infection or at high risk of complications from an infection.

Because a severe secondary bacterial infection of eczema could lead to a more serious illness or condition, such as cellulitis, the committee agreed that people who are systemically unwell, for example, with fever or malaise, should be offered an oral antibiotic. If the symptoms or signs of infection suggest cellulitis, the committee agreed that it should be managed with antibiotics as outlined in the NICE guideline on cellulitis and erysipelas: antimicrobial prescribing.

However, for people who are not systemically unwell, the committee agreed that an antibiotic is not routinely needed. This was based on evidence from a UK trial in children with clinically infected eczema. In this trial, a 7‑day course of topical fusidic acid or oral flucloxacillin had no benefit in terms of clinical effectiveness, quality of life or microbiological outcomes over standard treatment with topical corticosteroids.

Another trial in children, young people and adults with clinically infected eczema showed that topical fusidic acid plus a topical corticosteroid was not more effective than placebo plus a topical corticosteroid for clinical and biological response. The committee agreed, based on their experience, that this reinforced the importance of topical corticosteroid use during a flare. People should continue to use topical corticosteroids if their eczema is infected, matching the potency of the corticosteroid to the severity of eczema. This aligns with recommendations in the NICE guideline on atopic eczema in under 12s and in NICE's clinical knowledge summary on atopic eczema.

The committee agreed that if, after considering a person's history and clinical presentation, an antibiotic is clinically needed for infected eczema, a short course of a topical or oral antibiotic may be appropriate. The choice of a topical or oral antibiotic would be an individual clinical decision taking into account the extent and severity of symptoms or signs, and the risk of developing complications. Local antimicrobial resistance data, patient preference, administration practicalities (particularly to large areas), possible adverse effects and previous use would also need to be taken into account.

Antimicrobial resistance can develop rapidly with topical antibiotics. The committee agreed that repeated doses or extended use of the same topical antibiotic should be avoided. Evidence from a 2016 UK trial showed that there was more resistance to fusidic acid (after a 7‑day course) in S. aureus skin isolates than with oral flucloxacillin treatment. But there were no statistically significant differences in the trial in clinical effectiveness, adverse events, other antibiotic resistance outcomes or healthcare use between the topical and oral treatment. However, in a Danish trial from 2007 comparing topical fusidic acid plus a topical corticosteroid with placebo, there was no statistically significant difference between the groups in the number of S. aureus isolates resistant to fusidic acid after 14 days of treatment.

After discussing the evidence for antiseptics, the committee agreed that there was insufficient evidence on whether an antiseptic bath emollient was more effective than a standard bath emollient in children with infected eczema. Therefore, the committee made no recommendations on using antiseptic bath emollients, and made a recommendation for research.

The only evidence found for bleach baths (half a cup of 6% bleach in a bath, final concentration 0.005%; bathing for 5 to 10 minutes twice weekly) was a small trial of intranasal mupirocin (for decolonisation) plus a bleach bath compared with placebo in children and young people with secondary bacterial infection of eczema. This combination was more effective than placebo in children with infected eczema for several clinical-effectiveness outcomes. However, the committee agreed that this trial did not provide evidence that bleach baths alone are effective.

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Advice

Why the committee made the recommendations

Recommendations 1.1.8 and 1.1.9

A severe bacterial infection of eczema could lead to a more serious illness or condition, such as cellulitis. So, the committee agreed that people should be advised to seek medical help if their symptoms worsen rapidly or significantly at any time. This is particularly important if they did not have antibiotics initially, or their symptoms have not improved after completing a course of antibiotics.

However, people should also be advised that it can take time for infected eczema to resolve, and that there may not be full symptom resolution until after they have finished the course of antibiotics.

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Reassessment

Why the committee made the recommendations

Recommendations 1.1.10 to 1.1.14

Based on experience, the committee agreed when people with secondary bacterial infection of eczema should be reassessed. If symptoms of the infection worsen rapidly or significantly at any time, or do not start to improve after completing a course of antibiotics, this may indicate that the person has a more serious illness needing referral, or a resistant infection (possibly because of previous antibiotic use).

The committee agreed that people need to be reassessed if they are systemically unwell or have severe pain that is out of proportion to the infection (this can be a symptom of necrotising fasciitis, which is a rare but serious bacterial infection). The committee discussed that, at reassessment, it is important to consider other possible diagnoses, including viral (rather than bacterial) infection; for example, eczema herpeticum.

The committee agreed that it would be appropriate to send a skin swab for microbiological testing if the infection recurs frequently, and to consider doing this if the symptoms or signs of the infection are worsening or have not improved as expected. This will guide future antibiotic choice if the person has a resistant infection. A nasal swab should also be considered if nasal carriage of S. aureus is suspected. A nasal or skin (or both) decolonisation regimen should be considered, based on clinical judgement and microbiological test results, to remove the bacteria causing recurring infection. The committee agreed that decolonisation is supported by the small trial of intranasal mupirocin plus a bleach bath in children with infected eczema. The committee recognised that family decolonisation may sometimes be appropriate, but did not make a recommendation because this decision should be based on specialist advice.

The committee agreed on good practice for antimicrobial stewardship when reviewing the results of microbiological tests.

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Referral and seeking specialist advice

Why the committee made the recommendations

Recommendations 1.1.15 and 1.1.16

Based on their experience, the committee agreed that people with secondary bacterial infection of eczema who may have a more serious illness or condition need referral for further assessment and treatment in hospital.

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Choice of antibiotic

Why the committee made the recommendations

Recommendation 1.2.1

Topical antibiotic

Most of the evidence for topical antibiotics was for fusidic acid. The committee agreed that this was more effective than topical neomycin sulfate for microbiological outcomes in 1 trial. Topical mupirocin was more effective than oral cefalexin for some microbiological outcomes (but not others) in 1 trial. However, there was no evidence comparing topical mupirocin with topical fusidic acid.

Based on committee experience, current practice and limited evidence, the committee agreed that the first-choice topical antibiotic in adults, young people and children with secondary bacterial infection of eczema is fusidic acid 2% (either as a cream or an ointment). A topical rather than an oral antibiotic is more appropriate if the person is not systemically unwell, and the infection is localised and not severe. The committee discussed that, in the absence of strong evidence, fusidic acid 2% was the most appropriate first-choice topical antibiotic because topical mupirocin should be reserved for treating meticillin-resistant S. aureus (MRSA) colonisation.

Based on their experience and limited evidence, the committee agreed that fusidic acid resistance rates are higher than for some other antibiotics, so previous use should be considered to avoid extended or repeated use. National antimicrobial resistance data from Public Health England's voluntary surveillance reports on Staphylococcus aureus showed fusidic acid resistance rates of 13% for meticillin-susceptible S. aureus bloodstream infections and of 25% for MRSA bloodstream infections. However, the committee discussed that resistance rates in blood isolates may not be a good indicator of resistance rates in skin isolates. These can vary greatly from person to person based on their history of antibiotic use and between localities.

The committee did not recommend an alternative topical antibiotic for secondary bacterial infection of eczema. This was because, if fusidic acid is unsuitable or ineffective, an oral antibiotic is preferred.

Oral antibiotic

Based on their experience and knowledge of current practice, the committee agreed that the first-choice oral antibiotic in adults, young people and children with secondary bacterial infection of eczema is flucloxacillin. An oral rather than a topical antibiotic is more appropriate if the person is systemically unwell, or if the infection is widespread or severe. Flucloxacillin is a relatively narrow‑spectrum penicillin that is effective against S. aureus and S. pyogenes. The committee recognised that some children cannot tolerate flucloxacillin solution. However, they were aware of many useful resources that are available (for example, Medicines for Children's leaflet on helping your child to swallow tablets) to teach children how to swallow tablets or capsules. For children who are unable to swallow capsules, 1 of the alternative oral antibiotics is suitable.

The alternative oral antibiotics in adults, young people and children with penicillin allergy or if flucloxacillin is unsuitable, are clarithromycin or, in pregnancy, erythromycin. The committee agreed that these antibiotics are effective against the common pathogens that cause secondary bacterial infection of eczema.

The committee noted that, in their experience, MRSA infection in secondary bacterial infection of eczema is rare and that appropriate antibiotic choice may depend on local antimicrobial resistance rates. Therefore, they agreed that, if MRSA is suspected or confirmed, a local microbiologist should be consulted.

Course length and dosage

No evidence was identified for course length. Therefore, the recommendations were based on committee experience of current practice. The committee also agreed that the shortest course that is likely to be effective should be prescribed to reduce the risk of antimicrobial resistance and adverse effects. Based on their experience that lower doses (250 mg four times a day) of flucloxacillin are not clinically effective because of poor oral bioavailability, the committee agreed that the higher dose for flucloxacillin of 500 mg four times a day is appropriate for treating secondary bacterial infection of eczema in adults. They agreed that dose ranges are appropriate for children because the appropriate dose may vary depending on the severity of the infection and the age and weight of the child.

From their experience, the committee agreed that 5 to 7 days of treatment, based on clinical assessment, would be sufficient for treating secondary bacterial infection of eczema if an antibiotic was needed. The committee noted that this was a shorter duration than the previous recommendation in the NICE guideline on atopic eczema in under 12s, which says to use fusidic acid 2% for 1 to 2 weeks. They also discussed that the shorter duration had been recommended to provide effective treatment for the infection while reducing the risk of resistance occurring.

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Treatment

Why the committee made the recommendations

Recommendation 1.3.1

For this guideline, the committee considered the management of secondary bacterial infections in people with common skin conditions other than eczema, namely psoriasis, chicken pox, shingles and scabies. However, no evidence was found in these conditions. The committee agreed that it was not appropriate to extrapolate evidence from people with infected eczema to those with infected psoriasis, chicken pox, shingles or scabies. Therefore, no recommendations on the secondary bacterial infection of these other skin conditions were made, and the committee agreed that specialist advice should be sought where needed. The committee agreed that more research was needed on the optimum treatment of infected psoriasis, chicken pox, shingles and scabies, so made a recommendation for research.

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  • National Institute for Health and Care Excellence (NICE)