Exploring Staphylococcus epidermidis in atopic eczema: friend or foe?

BACKGROUND: Staphylococcus aureus (SA) colonization/infection is important in the pathophysiology of childhood atopic dermatitis (AD), but the role of Staphylococcus epidermidis (SE) is unknown. AIM: To evaluate if SE co-infects with SA and is associated with more severe disease. METHODS: Associations between bacteriological culture results of skin swabs (taken from the most severely affected area and at the antecubital fossa) and SCORing Atopic Dermatitis (SCORAD) score, skin hydration, transepidermal water loss (TEWL) and quality of life (QoL) were evaluated. RESULTS: In 100 consecutive patients with AD (aged 12.4 ± 4.8 years), SE was present in 28% and 32% of the swabs taken from the most severe area and the flexural area (antecubital fossa), respectively, whereas SA was present in 69% and 55%, respectively. Binomial logistic regression showed that SE was inversely associated with SA growth in the most severely affected skin site [adjusted odds ratio (aOR) = 0.42, 95% CI 0.22-0.81; P = 0.01], frequency of emollient usage (aOR = 0.50, 95% CI 0.29-0.87; P = 0.01) and frequency of oral antihistamine usage (aOR = 0.81, 95% CI 0.65-0.10, P < 0.05), but positively associated with objective SCORAD (aOR = 1.04, 95% CI 1.00-1.02; P < 0.05). SE in the antecubital fossa was not associated with SA growth, disease severity, QoL or any clinical parameters. CONCLUSIONS: SE may not be just a commensal bystander in the skin microbiota. The organism amensalistically displaces SA and is associated with more severe disease.

Efficacy of sodium hypochlorite (bleach) baths to reduce Staphylococcus aureus colonization in childhood onset moderate-to-severe eczema: A randomized, placebo-controlled cross-over trial.

BACKGROUND: Staphylococcus aureus (S. aureus) colonization/infection is an important factor in the pathophysiology of atopic dermatitis (AD). Clinical trials have demonstrated conflicting efficacy of diluted bleach baths in treating moderate-to-severe AD. We conducted a double-blinded, placebo-controlled (water), cross-over trial among patients with AD to investigate the efficacy of bleach baths in reducing S. aureus colonization and AD severity. METHOD: In this cross-over trial, 40 patients with moderate-to-severe AD were randomized to receive twice-weekly bleach and water baths, each for four consecutive weeks with a four-week wash-out period in between. Condition of S. aureus growth and SCORing Atopic Dermatitis index (SCORAD) were recorded at baseline and four-weekly intervals. Patients' blood was collected in first and second visits to investigate blood eosinophil count, serum levels of total IgE and specific IgEs against Staphylococcal enterotoxins A and B. In every visit, Children Dermatology Life Quality Index (CDLQI), skin hydration (SH), transepidermal water loss (TEWL) and usage frequency of prohibited medications (topical antibiotic, steroid and oral antihistamine) were recorded. RESULTS: All 40 patients completed the trial, but 14 were non-adherent. By intention-to-treat (ITT) approach, comparing with water baths, bleach baths conferred no significant efficacy in CDLQI, SH, TEWL, blood eosinophil count, total IgE and the two specific IgEs over four weeks. Water baths caused a greater reduction in affected area of SCORAD than bleach baths (-5.7 ± 15.4 for water vs. 0.6 ± 12.4 for bleach; p = 0.03) by ITT, and in objective SCORAD and affected area (p < 0.05) from per-protocol approach. Bleach baths reduced topical corticosteroid use (mean difference = 1.1 ± 2.6 days/week; p = 0.014) and topical antibiotic use (mean difference = 1.0 ± 2.8 days/week; p = 0.044) in within-group analysis. CONCLUSIONS: This study demonstrated that a four-week, twice-weekly regime of diluted bleach baths is not more useful than water baths in reducing S. aureus colonization/infection and improving AD. A longer treatment period is needed to evaluate if the short treatment duration was the main cause for the discrepancy in outcome from other bleach-bath trials. The usage of a portable bath tub obviates the problems associated with unavailability of bathing facilities in some families.