Date of Award
2026
Degree Name
Master of Science (Medicine)
Schools and Centres
Medicine
First Supervisor
Professor Asha Bowen
Second Supervisor
Professor Gerard Hoyne
Abstract
Recent interest in the diverse ecosystem of bacteria, fungi and viruses that make up the skin microbiome has led to numerous studies investigating the microbiome in healthy skin and in dermatological diseases. An imbalance of the normal skin microbial flora can cause some skin diseases, and current culture techniques are often unable to detect a microorganism to further our understanding of the clinical–microbiological correlates of disease and dysbiosis. Atopic dermatitis and rosacea are presentations that General practitioners (GPs) often manage that may have an infective or microbiological component and can be challenging to treat. Further research using culture-independent techniques is needed for conditions involving microbial dysbiosis to advance our knowledge of skin disease pathophysiology and guide future management. However, skin microbiome analysis is challenging due to relatively low numbers of skin microorganisms compared to mucosal sites, such as the respiratory or gastrointestinal tracts. Microbiome results are heavily influenced by sampling methods. Sampling methods on earlier occasions include that of cotton swabs, tape stripping, patch sampling and punch biopsies. It is essential to have a standardised sampling method for microbiome studies to have comparable results between studies.
The objective of this thesis is to utilise molecular tools as a means to further understand skin disease and the implications of the skin microbiome including the impact of dysbiosis on conditions such atopic dermatitis, rosacea and hidradenitis suppurativa. Our focus is to define the best approach for sampling the skin microbiome in healthy children and to explore whether sampling with a flocked swab or scrapings is superior to sample skin microorganisms (as determined by increased bacterial DNA yield, improved reproducibility over time and between left and right side of the body). Flocked swabs have been shown to have superior DNA extraction curves compared to cotton swabs (when studied at other sites e.g. nasopharynx, gut). Here we aimed to determine the optimal methods for sampling of the skin microbiome by comparing (1) sampling from different sites (cubital fossa, face, and axilla); (2) collection method (flocked swab vs. skin scrapings) and (3) reproducibility over time. Our discussions will focus on some clinical pearls for initial and future directions of the management of conditions such as atopic dermatitis, rosacea, and hidradenitis suppurativa and link how further research into the skin microbiome can be utilised clinically to assist in the management of these patients that often do not respond to routine antibiotics.
Samples were collected from six healthy children aged three to nine years from the skin overlying the cubital fossa, cheek and axilla using (i) flocked swabs and (ii) skin scrapings with a glass slide. Samples were collected from the left and right sides of the body at two separate time points, one week apart. Quantitative PCR of the gene encoding 16S ribosomal ribonucleic acid (rRNA) was performed to compare the bacterial load collected by each sampling method. Full-length 16S rRNA gene amplicon sequencing was carried out to compare the relationship of sampling method and time with the diversity and ecology of bacteria between different body sites.
From six children, 78 flocked swabs and 78 skin scraping samples were collected, along with details of their overall health and skin care practices. qPCR results indicated higher total bacterial load from flocked swabs compared with skin scrapings. Flocked swabs and skin scraping methods had comparable bacterial compositional profiles. The skin microbiome was diverse between individuals and remained relatively stable within individuals over time.
This study is one of the first studies in a healthy paediatric population to further assess the best methodology for sampling the skin microbiome (swab vs scrape). Results overall were closely aligned between sample types, however bacterial DNA yield was higher for flocked swab samples (compared to skin scraping methods) and with a simpler protocol is the preferred sampling method for future studies. Future novel work is needed to further explore the skin microbiome in clearly defined infectious diseases, in skin diseases that are exacerbated by infection, e.g., eczema, and in skin diseases that are treated with long-term antibiotics for the presumed but currently poorly defined role of bacterial pathogenesis, e.g., hidradenitis suppurativa. Understanding normal Optimisation of sampling for a new skin microbiome assay pilot study. Skin flora will help identify how microbial imbalance may be associated with skin disease and skin healing.
Publication Details
Smith, A. (2026). Optimisation of sampling for a new skin microbiome assay pilot study [Master of Science (Medicine)]. The University of Notre Dame Australia. https://researchonline.nd.edu.au/theses/482