Associations between early-life exposures and the infant skin microbiome

Conor Broderick; Casper Sahl Poulsen; Mathis Hjort Hjelmsø; Tom Marrs; Suzana Radulovic; Kirsty Logan; Xuanji Li; Ziqi Wu; Søren Johannes Sørensen; Bouchra Ezzamouri; Helen Alexander; Nanna Fyhrquist; Harri Alenius; Madhumita Bhattacharyya; Avidan U Neumann; Gideon Lack; Michael Perkin; Klaus Bønnelykke; Jakob Stokholm; Carsten Flohr

doi:10.1093/bjd/ljaf524

Associations between early-life exposures and the infant skin microbiome

Conor Broderick, Casper Sahl Poulsen, Mathis Hjort Hjelmsø, Tom Marrs, Suzana Radulovic, Kirsty Logan, Xuanji Li, Ziqi Wu, Søren Johannes Sørensen, Bouchra Ezzamouri, Helen Alexander, Nanna Fyhrquist, Harri Alenius, Madhumita Bhattacharyya, Avidan U Neumann, Gideon Lack, Michael Perkin, Klaus Bønnelykke, Jakob Stokholm, Carsten Flohr^*

^*Corresponding author af dette arbejde

Abstract

BACKGROUND: Factors influencing the early-life skin microbiome, and the association with atopic dermatitis (AD), are relatively unexplored.

OBJECTIVE: To evaluate associations with the infant skin microbiome during the first year of life.

METHODS: 3-month-old infants from the Enquiring About Tolerance (EAT) birth cohort were examined for AD at enrolment, 1 and 3 years of age. Parent-completed questionnaires, trans-epidermal water loss (TEWL), and filaggrin mutation status were evaluated. Bacterial swabs were collected from the elbow crease and volar forearm in 148 infants at 3 months and 1 year of age, and the microbiome composition was characterized using 16S rRNA gene sequencing (V3-V4 region).

RESULTS: Shannon diversity was significantly higher at the forearm compared to the elbow. Staphylococcus, Acinetobacter, and Streptococcus were the most abundant genera across time and body-site. Microbiome community composition was primarily associated with body-site and age (p≤0.001, both). Other significant associations were found with ethnicity (p=0.009), filaggrin status (p≤0.001), urban-vs-rural residence (p=0.005), older siblings (p=0.041), bath product usage at 3 months (p=0.011), but not with pets (p=0.159), systemic antibiotics (p=0.27) nor with bathing frequency (p=0.109). The microbiome was associated with elevated TEWL (3-months p=0.004, 1-year p≤0.001) and with concurrent AD (3-months p=0.027, 1-year p≤0.001). Streptococcus parasanguinis was significantly less abundant in non-lesional skin of infants with AD at 3 months.

CONCLUSION: In addition to age and body-site, the infant skin microbiome is associated with heritable factors, the home environment, hygiene practices, and with the presence of AD.

Originalsprog	Engelsk
Tidsskrift	British Journal of Dermatology
ISSN	0007-0963
DOI	https://doi.org/10.1093/bjd/ljaf524
Status	E-pub ahead of print - 16 jan. 2026

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10.1093/bjd/ljaf524Licens: CC BY-NC

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Broderick, C., Poulsen, C. S., Hjelmsø, M. H., Marrs, T., Radulovic, S., Logan, K., Li, X., Wu, Z., Sørensen, S. J., Ezzamouri, B., Alexander, H., Fyhrquist, N., Alenius, H., Bhattacharyya, M., Neumann, A. U., Lack, G., Perkin, M., Bønnelykke, K., Stokholm, J., & Flohr, C. (2026). Associations between early-life exposures and the infant skin microbiome. British Journal of Dermatology. Advance online publication. https://doi.org/10.1093/bjd/ljaf524

Broderick, C, Poulsen, CS, Hjelmsø, MH, Marrs, T, Radulovic, S, Logan, K, Li, X, Wu, Z, Sørensen, SJ, Ezzamouri, B, Alexander, H, Fyhrquist, N, Alenius, H, Bhattacharyya, M, Neumann, AU, Lack, G, Perkin, M, Bønnelykke, K , Stokholm, J & Flohr, C 2026, 'Associations between early-life exposures and the infant skin microbiome', British Journal of Dermatology. https://doi.org/10.1093/bjd/ljaf524

@article{b928709932784cbebfac1af7465354de,

title = "Associations between early-life exposures and the infant skin microbiome",

abstract = "BACKGROUND: Factors influencing the early-life skin microbiome, and the association with atopic dermatitis (AD), are relatively unexplored.OBJECTIVE: To evaluate associations with the infant skin microbiome during the first year of life.METHODS: 3-month-old infants from the Enquiring About Tolerance (EAT) birth cohort were examined for AD at enrolment, 1 and 3 years of age. Parent-completed questionnaires, trans-epidermal water loss (TEWL), and filaggrin mutation status were evaluated. Bacterial swabs were collected from the elbow crease and volar forearm in 148 infants at 3 months and 1 year of age, and the microbiome composition was characterized using 16S rRNA gene sequencing (V3-V4 region).RESULTS: Shannon diversity was significantly higher at the forearm compared to the elbow. Staphylococcus, Acinetobacter, and Streptococcus were the most abundant genera across time and body-site. Microbiome community composition was primarily associated with body-site and age (p≤0.001, both). Other significant associations were found with ethnicity (p=0.009), filaggrin status (p≤0.001), urban-vs-rural residence (p=0.005), older siblings (p=0.041), bath product usage at 3 months (p=0.011), but not with pets (p=0.159), systemic antibiotics (p=0.27) nor with bathing frequency (p=0.109). The microbiome was associated with elevated TEWL (3-months p=0.004, 1-year p≤0.001) and with concurrent AD (3-months p=0.027, 1-year p≤0.001). Streptococcus parasanguinis was significantly less abundant in non-lesional skin of infants with AD at 3 months.CONCLUSION: In addition to age and body-site, the infant skin microbiome is associated with heritable factors, the home environment, hygiene practices, and with the presence of AD.",

author = "Conor Broderick and Poulsen, \{Casper Sahl\} and Hjelms{\o}, \{Mathis Hjort\} and Tom Marrs and Suzana Radulovic and Kirsty Logan and Xuanji Li and Ziqi Wu and S{\o}rensen, \{S{\o}ren Johannes\} and Bouchra Ezzamouri and Helen Alexander and Nanna Fyhrquist and Harri Alenius and Madhumita Bhattacharyya and Neumann, \{Avidan U\} and Gideon Lack and Michael Perkin and Klaus B{\o}nnelykke and Jakob Stokholm and Carsten Flohr",

note = "{\textcopyright} The Author(s) 2026. Published by Oxford University Press on behalf of British Association of Dermatologists.",

year = "2026",

month = jan,

day = "16",

doi = "10.1093/bjd/ljaf524",

language = "English",

journal = "British Journal of Dermatology",

issn = "0007-0963",

publisher = "Oxford University Press",

}

TY - JOUR

T1 - Associations between early-life exposures and the infant skin microbiome

AU - Broderick, Conor

AU - Poulsen, Casper Sahl

AU - Hjelmsø, Mathis Hjort

AU - Marrs, Tom

AU - Radulovic, Suzana

AU - Logan, Kirsty

AU - Li, Xuanji

AU - Wu, Ziqi

AU - Sørensen, Søren Johannes

AU - Ezzamouri, Bouchra

AU - Alexander, Helen

AU - Fyhrquist, Nanna

AU - Alenius, Harri

AU - Bhattacharyya, Madhumita

AU - Neumann, Avidan U

AU - Lack, Gideon

AU - Perkin, Michael

AU - Bønnelykke, Klaus

AU - Stokholm, Jakob

AU - Flohr, Carsten

PY - 2026/1/16

Y1 - 2026/1/16

N2 - BACKGROUND: Factors influencing the early-life skin microbiome, and the association with atopic dermatitis (AD), are relatively unexplored.OBJECTIVE: To evaluate associations with the infant skin microbiome during the first year of life.METHODS: 3-month-old infants from the Enquiring About Tolerance (EAT) birth cohort were examined for AD at enrolment, 1 and 3 years of age. Parent-completed questionnaires, trans-epidermal water loss (TEWL), and filaggrin mutation status were evaluated. Bacterial swabs were collected from the elbow crease and volar forearm in 148 infants at 3 months and 1 year of age, and the microbiome composition was characterized using 16S rRNA gene sequencing (V3-V4 region).RESULTS: Shannon diversity was significantly higher at the forearm compared to the elbow. Staphylococcus, Acinetobacter, and Streptococcus were the most abundant genera across time and body-site. Microbiome community composition was primarily associated with body-site and age (p≤0.001, both). Other significant associations were found with ethnicity (p=0.009), filaggrin status (p≤0.001), urban-vs-rural residence (p=0.005), older siblings (p=0.041), bath product usage at 3 months (p=0.011), but not with pets (p=0.159), systemic antibiotics (p=0.27) nor with bathing frequency (p=0.109). The microbiome was associated with elevated TEWL (3-months p=0.004, 1-year p≤0.001) and with concurrent AD (3-months p=0.027, 1-year p≤0.001). Streptococcus parasanguinis was significantly less abundant in non-lesional skin of infants with AD at 3 months.CONCLUSION: In addition to age and body-site, the infant skin microbiome is associated with heritable factors, the home environment, hygiene practices, and with the presence of AD.

AB - BACKGROUND: Factors influencing the early-life skin microbiome, and the association with atopic dermatitis (AD), are relatively unexplored.OBJECTIVE: To evaluate associations with the infant skin microbiome during the first year of life.METHODS: 3-month-old infants from the Enquiring About Tolerance (EAT) birth cohort were examined for AD at enrolment, 1 and 3 years of age. Parent-completed questionnaires, trans-epidermal water loss (TEWL), and filaggrin mutation status were evaluated. Bacterial swabs were collected from the elbow crease and volar forearm in 148 infants at 3 months and 1 year of age, and the microbiome composition was characterized using 16S rRNA gene sequencing (V3-V4 region).RESULTS: Shannon diversity was significantly higher at the forearm compared to the elbow. Staphylococcus, Acinetobacter, and Streptococcus were the most abundant genera across time and body-site. Microbiome community composition was primarily associated with body-site and age (p≤0.001, both). Other significant associations were found with ethnicity (p=0.009), filaggrin status (p≤0.001), urban-vs-rural residence (p=0.005), older siblings (p=0.041), bath product usage at 3 months (p=0.011), but not with pets (p=0.159), systemic antibiotics (p=0.27) nor with bathing frequency (p=0.109). The microbiome was associated with elevated TEWL (3-months p=0.004, 1-year p≤0.001) and with concurrent AD (3-months p=0.027, 1-year p≤0.001). Streptococcus parasanguinis was significantly less abundant in non-lesional skin of infants with AD at 3 months.CONCLUSION: In addition to age and body-site, the infant skin microbiome is associated with heritable factors, the home environment, hygiene practices, and with the presence of AD.

U2 - 10.1093/bjd/ljaf524

DO - 10.1093/bjd/ljaf524

M3 - Journal article

C2 - 41542943

SN - 0007-0963

JO - British Journal of Dermatology

JF - British Journal of Dermatology

ER -

Associations between early-life exposures and the infant skin microbiome

Abstract

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