Search

Abstract There has been considerable research into the understanding of the healthy skin microbiome. Similarly, there is also a considerable body of research into whether specific microbes contribute to skin disorders, with atopic dermatitis (AD) routinely linked to increased Staphylococcus aureus (S. aureus) colonisation. In this study, the epidermal surface of participants was sampled using swabs, while serial tape-stripping (35 tapes) was performed to sample through the stratum corneum. Samples were taken from AD patients and healthy controls, and the bacterial communities were profiled by metabarcoding the universal V3-V4 16S rRNA region. Results show that the majority of bacterial richness is located within the outermost layers of the stratum corneum, however there were many taxa that were found almost exclusively at the very outermost layer of the epidermis. We therefore hypothesise that tape-stripping can be performed to investigate the ‘core microbiome’ of participants by removing environmental contaminants. Interestingly, significant community variation between AD patients and healthy controls was only observable at the epidermal surface, yet a number of individual taxa were found to consistently differ with AD status across the entire epidermis (i.e. both the epidermal surface and within the epidermis). Sampling strategy could therefore be tailored dependent on the hypothesis, with sampling for forensic applications best performed using surface swabs and outer tapes, while profiling sub-surface communities may better reflect host genome and immunological status.

The aim of this study was to investigate the early-life development of the skin microbiome in atopic dermatitis. Nineteen infants with atopic dermatitis and 19 healthy infants were evaluated 3 times, at 3 months intervals, within the first 30 months of life. Tape-strips were collected from volar forearms, cheeks, and eczema lesions, and the skin microbiome was assessed by 16S rRNA sequencing. Both the community structure and richness of the skin microbiome of infants with atopic dermatitis differed significantly from that of healthy infants, with greater richness in healthy infants. For infants with atopic dermatitis, the community composition was not dominated by Staphylococci. For healthy infants, community composition and richness correlated significantly with age, while such a pattern was not revealed in infants with atopic dermatitis. This suggests a slower maturation of the skin microbiome in atopic dermatitis, which precedes the staphylococcal predominance observed in older children and adults.

ABSTRACT Several factors have been shown to influence the composition of the bacterial communities inhabiting healthy skin, with variation between different individuals, differing skin depths, and body locations (spatial-temporal variation). Atopic dermatitis (AD) is a chronic skin disease also affecting the skin-associated bacterial communities. While the effects of AD have been studied on these processes individually, few have considered how AD disrupts the spatial-temporal variation of the skin bacteria as a whole (i.e., considered these processes simultaneously). Here, we characterized the skin-associated bacterial communities of healthy volunteers and lesional and nonlesional skin of AD patients by metabarcoding the universal V3-V4 16S rRNA region from tape strip skin samples. We quantified the spatial-temporal variation (interindividual variation, differing skin depths, multiple time points) of the skin-associated bacteria within healthy controls and AD patients, including the relative change induced by AD in each. Interindividual variation correlated with the bacterial community far more strongly than any other factors followed by skin depth and then AD status. There was no significant temporal variation found within either AD patients or healthy controls. The bacterial community was found to vary markedly according to AD severity, and between patients without and with filaggrin mutations. Therefore, future studies may benefit from sampling subsurface epidermal communities and considering AD severity and the host genome in understanding the role of the skin bacterial community within AD pathogenesis rather than considering AD as a presence-absence disorder. IMPORTANCE The bacteria associated with human skin may influence skin barrier function and the immune response. Previous studies have attempted to understand the factors that regulate the skin bacteria, characterizing the spatial-temporal variation of the skin bacteria within unaffected skin. Here, we quantified the effect of AD on the skin bacteria on multiple spatial-temporal factors simultaneously. Although significant community variation between healthy controls and AD patients was observed, the effects of AD on the overall bacterial community were relatively low compared to other measured factors. Results here suggest that changes in specific taxa rather than wholesale changes in the skin bacteria are associated with mild to moderate AD. Further studies would benefit from incorporating the complexity of AD into models to better understand the condition, including AD severity and the host genome, alongside microbial composition.

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.