Definition and detection of the suboptimal health state of skin via skin microbiota. (a) Map of nonlesional samples on the skin. Beijing cohort, sites symmetrical to the lesional sites; Qingdao cohort, the symmetric sites of the lesional sites, plus another two remote sites on forearm or shank; Denver cohort, the surrounding, lesion-free skin of the lesional sites. (b) MiSH of nonlesional samples in the three cities compared to those of healthy and lesional samples. (c) MiSH of Qingdao nonlesional samples, which include one symmetric site (arm; “symmetric”) and two remote sites (leg; “distant” and “distant & symmetric”). (d) Profiles of the dominant genera (average relative abundance, >1%) in healthy, nonlesional, and lesional samples. In each of the three cities, the nonlesional microbiota is more similar to lesional ones than to healthy ones.