Microbiota of Demodex mites from rosacea patients and controls.

Proliferation of Demodex mites is associated with rosacea. Furthermore, Demodex-associated bacteria were suggested to play a role in the pathogenesis of rosacea. We decided to analyze Demodex microbiota. Mites were collected by standardized skin surface biopsies from patients with erythematotelangiectatic, papulopustular rosacea or from control subjects. The microbiota from each mite was characterized by 16S rRNA clone library approach. The 16S rRNA clone library consisted of 367 clones obtained from 73 extracts originating from 5 samples per study group (ETR, PPR or healthy subjects). A total of 86 species were identified with 36 as Demodex-specific microbiota. In the papulopustular group, proportions of Proteobacteria and Firmicutes increased whereas proportion of Actinobacteria decreased. Here, we report preliminary results on the microbiota of Demodex mites based on a molecular approach showing an unexpected diversity. Differences according to the host status need to be confirmed but open new perspectives for diagnostic of rosacea.