Skin pH–dependent Staphylococcus aureus abundance as predictor for increasing atopic dermatitis severity

Claudia Hülpüsch, Karolina Tremmel, Gertrud Hammel, Madhumita Bhattacharyya, Amedeo de Tomassi, Thomas Nussbaumer, Avidan U. Neumann, Matthias Reiger, Claudia Traidl-Hoffmann

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


Background: Atopic eczema (atopic dermatitis, AD) is characterized by disrupted skin barrier associated with elevated skin pH and skin microbiome dysbiosis, due to high Staphylococcus aureus loads, especially during flares. Since S aureus shows optimal growth at neutral pH, we investigated the longitudinal interplay between these factors and AD severity in a pilot study. Method: Emollient (with either basic pH 8.5 or pH 5.5) was applied double-blinded twice daily to 6 AD patients and 6 healthy (HE) controls for 8 weeks. Weekly, skin swabs for microbiome analysis (deep sequencing) were taken, AD severity was assessed, and skin physiology (pH, hydration, transepidermal water loss) was measured. Results: Physiological, microbiome, and clinical results were not robustly related to the pH of applied emollient. In contrast to longitudinally stable microbiome in HE, S aureus frequency significantly increased in AD over 8 weeks. High S aureus abundance was associated with skin pH 5.7-6.2. High baseline S aureus frequency predicted both increase in S aureus and in AD severity (EASI and local SCORAD) after 8 weeks. Conclusion: Skin pH is tightly regulated by intrinsic factors and limits the abundance of S aureus. High baseline S aureus abundance in turn predicts an increase in AD severity over the study period. This underlines the importance and potential of sustained intervention regarding the skin pH and urges for larger studies linking skin pH and skin S aureus abundance to understand driving factors of disease progression.

Original languageEnglish
Pages (from-to)2888-2898
Number of pages11
JournalAllergy: European Journal of Allergy and Clinical Immunology
Issue number11
StatePublished - 1 Nov 2020


  • Staphylococcus aureus
  • atopic dermatitis
  • microbiome
  • pH
  • skin


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