Efficient isolation and observation of the most complex human commensal, Demodex spp

• Published in: Experimental & applied acarology Vol. 76; no. 1; pp. 71 - 80
• Main Authors: Clanner-Engelshofen, B. M., Ruzicka, T., Reinholz, M.
• Format: Journal Article
• Language: English
• Published: Cham Springer Science and Business Media LLC 01.09.2018; Springer International Publishing; Springer Nature B.V
• Subjects: acarology; Animal Ecology; Animal Genetics and Genomics; Animal Systematics/Taxonomy/Biogeography; Animals; Biomedical and Life Sciences; Centrifugation; Coloring Agents; Commensals; Cultivation; death; Demodex; Entomology; Fluorescence; Host-Parasite Interactions; Humans; in vitro culture; Iodides; Life cycle engineering; Life cycles; Life Sciences; microbiome; Microbiomes; Mite Infestations; Mite Infestations - diagnosis; Mite Infestations - parasitology; Mites; Mites - physiology; Parasitology; Parasitology - methods; physiology; Propidium; Propidium iodide; Rosacea; sebum; Skin; skin (animal); Skin diseases; staining; Staining and Labeling; Staining and Labeling - methods; Sucrose; Sugar; Symbiosis; Viability assay; Mite; Micro-animal; Fluorescence microscopy
• ISSN: 0168-8162; 1572-9702; 1572-9702
• DOI: 10.1007/s10493-018-0289-0

Demodex spp. mites are an often neglected member of the human skin microbiome. Mostly they are commensals, although their pathophysiological role in rosacea, spinulosis folliculorum, and other skin diseases is recognized. Little is known about their life cycle, biology, and physiology. Demodex mites cannot be cultivated in vitro, thereby complicating research immensely. The manual extraction from human sebum is laborious and death can only be detected by surrogate markers like ceased movement or loss of fluorescence. Here we present a new approach for the extraction of larger mite numbers and the hitherto most precise way to detect death. The extraction of mites from sebum and debris by hand can be accelerated by a factor 10 using sucrose gradient centrifugation, which is well tolerated by the mites. Staining with propidium iodide allows for easy identification of dead mites, excluding frail mites that stopped moving, and has no negative effect on overall mite survival. We anticipate our methods to be a starting point for more sophisticated research and ultimately in vitro cultivation of Demodex spp. mites.