Cutibacterium acnes (C. acnes) is an organism implicated in the pathogenesis of acne. Despite regular immersion in antimicrobial chlorine, adolescent swimmers suffer from acne and tend to be resistant to standard therapies. Given the presence of Pseudomonas within swimming facilities, we hypothesized that “swimmer acne” is potentially driven by a different microbial mechanism. In this study, we aimed to examine the microbial dynamics of C. acnes and Pseudomonadaceae, a family of gram‐negative bacteria (includes Pseudomonas aeruginosa), in swimmers and its potential contribution to the pathogenesis of acne in this population. Using fluorescence photography that measures the Coproporphyrin III (CPIII), we quantitated an absolute abundance of C. acnes present on the face of each participant pre‐ and post‐swimming. In addition, 16S rRNA gene sequencing was utilized to assess relative abundance of the skin microbiota on each participant pre‐ and post‐swimming. 16 swimmers (8 girls and 8 boys) completed the study. Seven had acne on the face. The CPIII fluorescence levels decreased for all swimmers after 1 h of swimming (p‐value <0.001). In contrast, the relative abundance of C. acnes remained unchanged, while that of Pseudomonadaceae increased after swimming (p‐value =0.027). Comparing the relative abundances of Pseudomonadaceae before swimming, there was a significant increase in variance from the mean in acne group as compared to no acne group (p‐value <0.001). Taken together, we conclude that the skin dysbiosis resulting from repeated decolonization and colonization of C. acnes and Pseudomonadaceae, respectively, can potentially be associated with the pathogenesis of acne in swimmers.

Rhododendrol (RD) is a skin whitening ingredient that was developed in Japan. Among the 800,000 users of RD-containing cosmetics, 20,000 patients developed localized leukoderma (RD-induced leukoderma). Forty-two % of those users showed perilesional hyperpigmentation (leukomelanoderma), and 14% of them were associated with vitiligo vulgaris afterwards. The aim of this study is to investigate the risk factors affecting the severity of RD-induced leukoderma, the occurrence of leukomelanoderma, and the association with vitiligo vulgaris. For this retrospective cohort study, we abstracted data from our dermatology medical records of 101 patients who developed leukoderma after using the cosmetics containing RD from July 2013 to December 2014. Age, BMI, the number of RD-containing products they used, smoking history and depigmentation scores at their baseline visit as well as blood test data for anti-nuclear and/or anti-thyroid antibodies were analyzed. Multivariable logistic regression and linear regression were used for analyses of leukomelanoderma, vitiligo vulgaris and characteristics at the baseline visit. Age, the number of RD-containing products used, BMI, anti-nuclear and anti-thyroid antibodies were not significantly correlated with the presence of leukomelanoderma, but it appeared that leukomelanoderma was more likely to occur in patients who had a smoking history (p¼0.006). In addition, smokers showed a significant increase in their depigmentation score at the baseline visit (p¼0.03). Our study demonstrates that smoking is associated with the severity of RD-induced leukoderma and the occurrence of leukomelanoderma.

Swimmers often complain of dry skin, consistent with decreased skin sebum levels, and yet may also have acne, which is commonly related to elevated sebum levels.Sixteen adolescent swimmers with and without acne were enrolled to examine two markers of facial sebum levels before and after 1 hour of swimming. Swimmers with acne did not have significant decreases in their sebum levels or shine measurements after swimming, whereas swimmers without acne did. Overall, swimming may remove superficial sebum more than follicular sebum and therefore leave swimmers subject to both dry skin and acne simultaneously.