<i>Corynebacterium kroppenstedtii</i> subsp. <i>demodicis</i> is the endobacterium of <i>Demodex folliculorum</i>

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p><jats:italic>Demodex</jats:italic> spp. mites are the most complex member of the human skin microbiome. Mostly they are commensals, although their pathophysiological role in inflammatory dermatoses is recognized. Demodex mites cannot be cultivated <jats:italic>in vitro</jats:italic>, so only little is known about their life cycle, biology and physiology. Different bacterial species have been suggested to be the endobacterium of Demodex mites, including <jats:italic>Bacillus oleronius</jats:italic>,<jats:italic> B. simplex</jats:italic>,<jats:italic> B. cereus</jats:italic> and <jats:italic>B. pumilus</jats:italic>.</jats:p></jats:sec><jats:sec><jats:title>Objectives</jats:title><jats:p>Our aim was to find the true endobacterium of human Demodex mites.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>The distinct genetic and phenotypic differences and similarities between the type strain and native isolates are described by <jats:styled-content style="fixed-case">DNA</jats:styled-content> sequencing, <jats:styled-content style="fixed-case">PCR</jats:styled-content>,<jats:styled-content style="fixed-case"> MALDI</jats:styled-content>‐<jats:styled-content style="fixed-case">TOF</jats:styled-content>,<jats:styled-content style="fixed-case"> DNA</jats:styled-content>‐<jats:styled-content style="fixed-case">DNA</jats:styled-content> hybridization, fatty and mycolic acid analyses, and antibiotic resistance testing.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>We report the true endobacterium of <jats:italic>Demodex folliculorum</jats:italic>, independent of the sampling source of mites or life stage: <jats:italic>Corynebacterium kroppenstedtii</jats:italic> subsp. <jats:italic>demodicis</jats:italic>.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>We anticipate our finding to be a starting point for more in‐depth understanding of the tripartite microbe–host interaction between <jats:italic>Demodex</jats:italic> mites, its bacterial endosymbiont and the human host.</jats:p></jats:sec>