The Skin Microbiome of Patients With Atopic Dermatitis Normalizes Gradually During Treatment

Background

Atopic dermatitis (AD) is characterized by an altered skin microbiome dominantly colonized by S. aureus. Standard treatment includes emollients, anti-inflammatory medications and antiseptics.

Objectives

To characterize changes in the skin microbiome during treatment for AD.

Methods

The skin microbiomes of children with moderate-to-severe AD and healthy children were investigated in a longitudinal prospective study. Patients with AD were randomized to receive either standard treatment with emollients and topical corticosteroids or standard treatment with the addition of dilute bleach baths (DBB) and sampled at four visits over a three-month period. At each visit, severity of AD was measured, swabs were taken from four body sites and the composition of the microbiome at those sites was assessed using 16S rRNA amplification.

Results

We included 14 healthy controls and 28 patients. We found high relative abundances of S. aureus in patients, which correlated with AD severity and reduced apparent alpha diversity. As disease severity improved with treatment, the abundance of S. aureus decreased, gradually becoming more similar to the microbiomes of healthy controls. After treatment, patients who received DBB had a significantly lower abundance of S. aureus than those who received only standard treatment.

Conclusions

There are clear differences in the skin microbiome of healthy controls and AD patients that diminish with treatment. After three months, the addition of DBB to standard treatment had significantly decreased the S. aureus burden, supporting its use as a therapeutic option. Further study in double-blinded trials is needed.

Caracterización, por RAPD-PCR, de aislados de Pseudomonas aeruginosa obtenidos de pacientes con fibrosis quística

OBJECTIVE

To characterize P. aeruginosa strains isolated from bronchoalveolar lavage fluid of cystic fibrosis (CF) patients over a 3 year period.

MATERIAL AND METHODS

A prospective follow-up study was carried out in a population of cystic fibrosis patients. The random amplified polymorphic DNA (RAP.D) technique was used to amplify DNA of P. aeruginosa strains isolated from bronchoalveolar lavage fluid samples of five CF patients from the Servicio de Neumología y Cirugía del Tórax del Instituto Nacional de Pediatría (Mexico City Chest Clinic of the National Pediatrics Institute) in Mexico City, between June 1996 and June 2002. Amplification patterns were established for each isolate to accurately identify all strains and to carry out an epidemiological analysis of P. aeruginosa among the selected CF patients.

RESULTS

Eighteen different DNA amplification patterns were defined and used to identify each P. aeruginosa strain isolated from the different bronchoalveolar lavage samples. No correlation was observed between the different P. aeruginosa strain genotypes and mucoid or non-mucoid phenotypes, as strains with different phenotypes showed similar amplification patterns. Several strains with different amplification patterns were identified in samples obtained from the same patient, suggesting coinfection with ore than one P. aeruginosa strain. Two siblings with CF shared similargenotypes, suggesting the occurrence of cross- contamination. Similar genotypes of P. aeruginosa strains were isolated throughout the study period.

CONCLUSION

Genotypic characterization of P. aeruginosa strains in CF patients allows more accurate epidemiological analyses of this important host-agent relationship.