Interventions to reduce Staphylococcus aureus in the management of eczema

Staphylococcus aureus (S. aureus) can cause secondary infection in eczema, and may promote inflammation in eczema that does not look infected. There is no standard intervention to reduce S. aureus burden in eczema. It is unclear whether antimicrobial treatments help eczema or promote bacterial resistance. This is an update of a 2008 Cochrane Review.

To assess the effects of interventions to reduce S. aureus for treating eczema.

We updated our searches of the following databases to October 2018: Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase and LILACS. We searched five trials registers and three sets of conference proceedings. We checked references of trials and reviews for further relevant studies. We contacted pharmaceutical companies regarding ongoing and unpublished trials.

Randomised controlled trials of products intended to reduce S. aureus on the skin in people diagnosed with atopic eczema by a medical practitioner. Eligible comparators were a similar treatment regimen without the anti-staphylococcal agent.

We used standard methodological procedures expected by Cochrane. Our key outcomes were participant- or assessor-rated global improvement in symptoms/signs, quality of life (QOL), severe adverse events requiring withdrawal, minor adverse events, and emergence of antibiotic-resistant micro-organisms.

We included 41 studies (1753 analysed participants) covering 10 treatment categories. Studies were conducted mainly in secondary care in Western Europe; North America; the Far East; and elsewhere. Twelve studies recruited children; four, adults; 19, both; and six, unclear. Fifty-nine per cent of the studies reported the mean age of participants (range: 1.1 to 34.6 years). Eczema severity ranged from mild to severe. Many studies did not report our primary outcomes. Treatment durations ranged from 10 minutes to 3 months; total study durations ranged from 15 weeks to 27 months. We considered 33 studies at high risk of bias in at least one domain. We present results for three key comparisons. All time point measurements were taken from baseline. We classed outcomes as short-term when treatment duration was less than four weeks, and long-term when treatment was given for more than four weeks. Fourteen studies evaluated topical steroid/antibiotic combinations compared to topical steroids alone (infective status: infected (two studies), not infected (four studies), unspecified (eight studies)). Topical steroid/antibiotic combinations may lead to slightly greater global improvement in good or excellent signs/symptoms than topical steroid alone at 6 to 28 days follow-up (risk ratio (RR) 1.10, 95% confidence interval (CI) 1.00 to 1.21; 224 participants; 3 studies, low-quality evidence). There is probably little or no difference between groups for QOL in children, at 14 days follow-up (mean difference (MD) -0.18, 95% CI -0.40 to 0.04; 42 participants; 1 study, moderate-quality evidence). The subsequent results for this comparison were based on very low-quality evidence, meaning we are uncertain of their validity: severe adverse events were rare (follow-up: between 6 to 28 days): both groups reported flare of dermatitis, worsening of the condition, and folliculitis (325 participants; 4 studies). There were fewer minor adverse events (e.g. flare, stinging, itch, folliculitis) in the combination group at 14 days follow-up (218 participants; 2 studies). One study reported antibiotic resistance in children at three months follow-up, with similar results between the groups (65 participants; 1 study). Four studies evaluated oral antibiotics compared to placebo (infective status: infected eczema (two studies), uninfected (one study), one study's participants had colonisation but no clinical infection). Oral antibiotics may make no difference in terms of good or excellent global improvement in infants and children at 14 to 28 days follow-up compared to placebo (RR 0.80; 95% CI 0.18 to 3.50; 75 participants; 2 studies, low-quality evidence). There is probably little or no difference between groups for QOL (in infants and children) at 14 days follow-up (MD 0.11, 95% CI -0.10 to 0.32, 45 participants, 1 study, moderate-quality evidence). The subsequent results for this comparison were based on very low-quality evidence, meaning we are uncertain of their validity: adverse events requiring treatment withdrawal between 14 to 28 days follow-up were very rare, but included eczema worsening (both groups), loose stools (antibiotic group), and Henoch-Schönlein purpura (placebo group) (4 studies, 199 participants). Minor adverse events, including nausea, vomiting, diarrhoea, and stomach and joint pains, at 28 days follow-up were also rare and generally low in both groups (1 study, 68 infants and children). Antibiotic resistance at 14 days was reported as similar in both groups (2 studies, 98 infants and children). Of five studies evaluating bleach baths compared to placebo (water) or bath emollient (infective status: uninfected (two studies), unspecified (three studies)), one reported global improvement and showed that bleach baths may make no difference when compared with placebo at one month follow-up (RR 0.78, 95% CI 0.37 to 1.63; 36 participants; low-quality evidence). One study showed there is probably little or no difference in QOL at 28 days follow-up when comparing bleach baths to placebo (MD 0.90, 95% CI -1.32 to 3.12) (80 infants and children; moderate-quality evidence). We are uncertain if the groups differ in the likelihood of treatment withdrawals due to adverse events at two months follow-up (only one dropout reported due to worsening itch (placebo group)) as the quality of evidence was very low (1 study, 42 participants). One study reported that five participants in each group experienced burning/stinging or dry skin at two months follow-up, so there may be no difference in minor adverse events between groups (RR 1.00, 95% CI 0.35 to 2.87, 36 participants, low-quality evidence). Very low-quality evidence means we are also uncertain if antibiotic resistance at four weeks follow-up is different between groups (1 study, 80 participants ≤ 18 years).

We found insufficient evidence on the effects of anti-staphylococcal treatments for treating people with infected or uninfected eczema. Low-quality evidence, due to risk of bias, imprecise effect estimates and heterogeneity, made pooling of results difficult. Topical steroid/antibiotic combinations may be associated with possible small improvements in good or excellent signs/symptoms compared with topical steroid alone. High-quality trials evaluating efficacy, QOL, and antibiotic resistance are required.