Dr. Joseph Lam (biography and disclosure)
What I did before
Atopic dermatitis (AD) is a chronic relapsing disease which involves pruritus and eczematous lesions, affecting 15% to 20% of the childhood population (1). Staphylococcus aureus infection is the most common complication of AD.
Patients with AD have a very high rate of S aureus colonization (76-100%) as compared to healthy controls (2-25%) (2, 3). Even when the S aureus is not causing a bacterial superinfection, its presence can exacerbate AD through superantigens which induce the release of proinflammatory cytokines.
While S aureus can be treated with topical and/or systemic antibiotics, it is preferable to avoid frequent antibiotic use on patients, especially with the emergence of community-acquired methicillin-resistant S aureus (CA-MRSA).
What changed my practice
In 2009, Huang et al published a study looking at whether or not suppression of S aureus growth with sodium hypochlorite (bleach) baths and intranasal mupirocin improves AD severity (4). In this study, they took 31 patients (aged 6 months to 17 years) with moderate to severe AD and evidence of bacterial infection and randomized them to receive active treatment versus placebo (they did not do bleach-only or no mupirocin group). After treating all with a 2 week course of cephalexin, participants were instructed to add 1/2 cup (0.12 L) of 6% bleach (treatment group) or water (placebo group) to a full bath of water and to bathe in this solution twice weekly for 3 months. Participants were also asked to apply mupirocin ointment (treatment group) or petroleum ointment (placebo group) intranasally for 5 consecutive days, once per month for 3 months.
After 3 months, the treatment group had a dramatic difference in their Eczema Area and Severity Index (EASI) score compared with placebo. As well, participants in the treatment group also showed a greater mean reduction in the proportion of BSA (body surface area) affected at both 1 and 3 month. Interestingly, these differences were only seen in the submerged areas, and not in the head and neck areas.
What I do now
Although the hallmark of AD treatment is education, avoidance of triggers, moisturization and topical anti-inflammatory medications (topical corticosteroids or topical calcineurin inhibitors), dilute bleach baths are an effective adjuvant antiinfective treatment that can help decrease the number of local skin infections and reduce the need for systemic antibiotics for patients with AD with heavily colonized and/or superinfected skin. I usually recommend 1/2 cup of 6% bleach for 1/3 to 1/2 of an adult bathtub. Earlier studies looking at the concentration needed to kill a resistant bacteria known as methicillin-resistant Staph aureus (MRSA) used higher concentrations (5). In general, I recommend to avoid getting this in the eyes and to use caution in those with a known allergy to bleach. However, practically, there are no significant side-effects. This concentration of dilute bleach is similar to what was used in the past to sterilize water.
References (Note: Article requests might require a login ID with CPSBC or UBC)
1. Eichenfield LF. Consensus guidelines in diagnosis and treatment of atopic dermatitis. Allergy. 2004;59(suppl 78):86–92 (View article with CPSBC or UBC)
2. Higaki S, Morohasi M, Yamagishi T, Hasegawa Y. Comparative study of staphylococci from the skin of atopic dermatitis patients and from healthy subjects. Int J Dermatol. 1999;38(4): 265–269 9. (View article with CPSBC or UBC)
3. Abeck D, Mempel M. Staphylococcus aureus colonization in atopic dermatitis and its therapeutic implications. Br J Dermatol. 1998;139(suppl 53):13–16. (View article with CPSBC or UBC)
4. Huang JT, Abrams M, Tlougan B, Rademaker A, Paller AS. Treatment of Staphylococcus aureus colonization in atopic dermatitis decreases disease severity. Pediatrics. 2009 May;123(5):e808-14. (View article with CPSBC or UBC)
5. Fisher RG, Chain RL, Hair PS, Cunnion KM.Hypochlorite killing of community-associated methicillin-resistant Staphylococcus aureus. Pediatr Infect Dis J. 2008 Oct;27(10):934-5 (Abstract, or view with CPSBC or UBC)