Skin Microbiome in Patients with Hand Eczema and Healthy Controls: A Three-week Prospective Study

Abstract

The pathogenesis of chronic hand eczema remains unclear. Insights into the skin microbiome in hand eczema and its potential relevance to disease severity may help to elucidate the underlying mechanisms of hand eczema. The aim of this study was to characterize the microbiome in patients with hand eczema and healthy controls. A 5-visit prospective study was conducted over a period of 3 weeks. At each visit, bacterial swabs were taken from the hands of patients with hand eczema and controls. The microbiome was examined using DNA extraction and 16S rRNA amplicon sequencing (V3-V4 regions). Fifty patients with hand eczema and 50 controls were included (follow-up rate=100%). The baseline bacterial α-diversity was reduced on the hands of patients with hand eczema compared with controls (effect size=-0.31; 95% confidence interval (95% CI) -0.50; -0.11; p = 0.003). The dysbiosis on the patients' hands was stable over the study period, was associated with disease severity, and was characterized by reduced bacterial diversity and different bacterial community compositions.

Fig. 1

Bacterial diversity stratified by sample site. The α-diversity, measured using the Shannon index: (a) on the hands and (b) in the nose of patients with hand eczema and healthy controls. Skin bacterial community structures (β-diversity) (c) on the hands of patients and controls, and (d) in the nose shown in principal coordinates analysis (PCoA) plots. Statistical significance: *p < 0.05, **p < 0.01, ***p < 0.001.

Fig. 2

Staphylococcal communities on the hands and in the nose of patients with hand eczema (HE). Barplots showing the relative abundance per patient of bacteria on (a) lesional skin, (b) non-lesional skin, and (c) in nose with a specific focus on S. aureus, S. epidermidis and S. hominis. Samples collected from the same patients are shown in the same order in all 3 panels and sorted by S. aureus abundance on lesional skin. Disease severity (HECSI), sample site, and hand eczema subtype are illustrated. acd: allergic contact dermatitis; icd: irritant contact dermatitis.

Fig. 3

Disease severity in relation to bacterial diversity and community structure. (a) The α-diversity, measured by the Shannon index (Wilcoxon rank sum test), and (b) β-diversity at baseline stratified by disease severity groups. Statistical significance: *p < 0.05, **p < 0.01, ***p < 0.001.

Fig. 4

Temporal variations in S. aureus relative abundance. Boxplot of S. aureus relative abundance for patients with S. aureus at 1 or more visits. (a) Patients with improvement in disease severity from baseline to 3 weeks later (n = 29), and (b) patients with no improvement in severity (n = 9). Improvement in disease severity was defined as a decrease in hand eczema severity score, HECSI ≥ 1. Wilcoxon signed-rank test (paired) were used to compare S. aureus relative abundance at visit 1 with visit 5 for each group (“improvement” and “no improvement”), respectively.