The healing process of diabetic ulcers correlates with changes in the cutaneous microbiota.

Skin microbiota plays an essential role in the development and function of the cutaneous immune system, in the maintenance of the skin barrier through the release of antimicrobial peptides, and in the metabolism of some natural products. With the aim of characterizing changes in the cutaneous microbiota specifically associated with wound healing in the diabetic condition, we performed a 16 S rRNA gene Next Generation Sequencing of skin swabs taken within the ulcer bed of ten diabetic patients before (t0) and after 20 days of therapy (t20) with a fluorescein-based galenic treatment. Considering the twenty most representative genera, we found at t20 an increase of Corynebacterium, Peptostreptococcus, and Streptococcus, and a decrease of Enterococcus, Finegoldia, and Peptoniphilus genera. However, differences were not significant due to the high variability among samples and the small patient cohort. S. aureus was the most abundant species at t0 and was reduced by therapy in four patients. Comparing the microbiome in the ulcer bed and in the perilesional tissue of the same patient at t0, no major differences were observed. Taken together, our data indicate that in the absence of antibiotic-based therapy the healing process of diabetic ulcers is accompanied by changes in the microbiome composition.