The role of bacterial colonisation in severity, symptoms and aetiology of hand eczema: The importance of Staphylococcus aureus and presence of commensal skin flora.

BACKGROUND: The role and causality of the microbial ecosystem on the skin in relation to the development of hand eczema (HE) is still unknown. OBJECTIVES: To investigate the prevalence of different bacterial colonisations in HE patients and their association with the severity, symptoms and aetiology of the disease. METHODS: In a retrospective cohort study of 167 HE patients, bacterial swabs from lesional skin were collected for culturing. Patients were categorised according to bacterial colonisation, HE severity, HE symptoms and HE aetiology. RESULTS: The majority of the patients were tested positive for Staphylococcus aureus (S. aureus) (n = 131, 78.4%) and/or commensal skin flora (CSF; n = 130, 77.8%), while other bacteria species were found only sporadically. Severe HE was significantly more prevalent in skin with S. aureus (odds ratio [OR]: 5.13, 95% confidence interval [CI]: 2.21-11.94) and less common in skin with CSF (OR: 0.20, 95% CI: 0.05-0.88). S. aureus colonisation was also associated with atopic HE aetiology (p < 0.001) and acute HE symptoms such as blisters, erosions and crusts (p = 0.003). CONCLUSIONS: The main colonisation of HE patients is with S. aureus and is associated with disease severity, acute HE symptoms and atopic HE aetiology. CSF is associated with mild HE, which could result in new therapeutic approaches.