Microbial skin colonization in patients with atopic dermatitis: Association with immunological parameters and clinical disease severity

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by impaired epidermal barrier function, immune dysregulation, and altered microbial ecology. Over recent decades, there has been a steady increase in its prevalence, making AD one of the most pressing issues in dermatology. The aim of this study was to comprehensively assess bacterial skin colonization in patients with AD using real-time quantitative PCR and to analyze its relationship with clinical and immunological parameters of the disease. A prospective study included 110 patients with AD and 86 apparently healthy individuals. The disease severity was assessed using the SCORAD index; total IgE levels and complete blood count were measured, and quantification of skin microbiota was performed by real-time PCR. The results revealed a significant increase in bacterial load in the AD group compared to controls: total bacterial mass was 32 times higher, while Staphylococcus spp. and Staphylococcus aureus were 100 times higher. The concentration of Streptococcus spp. did not differ significantly. A strong positive correlation was found between the SCORAD index, total IgE level, absolute eosinophil count, and the quantity of total bacterial mass, Staphylococcus spp., and S. aureus, whereas a weak negative correlation was observed for Streptococcus spp. Patients with severe AD had significantly higher IgE levels. The obtained data confirm the central role of S. aureus and microbial dysbiosis in AD pathogenesis. The established threshold values of bacterial load (total bacterial mass > 5.0 log copies/mL, S. aureus > 4.0 log copies/mL) may serve as objective criteria for prescribing targeted antimicrobial therapy.

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