The Skin Microbiome Profile of Contact Sports Athletes—Focus on Sexual Dimorphism and Athlete–Non-Athlete Differences

Background: Athletes’ skin is exposed to increased microbial challenges due to rigorous physical activity, perspiration, constant “skin-to-skin” contact, frequent showering, use of hygiene products, and environmental factors present in training settings. This study aims to characterize the skin microbiome communities of young wrestlers and kickboxers in comparison with their non-athlete age-peers. Methods: A total of 56 combat sport athletes (30 males and 26 females, mean age ± SD = 18.2 ± 1.5 years) and 25 non-athlete youths (control group: 13 males and 12 females, mean age ± SD = 19.8 ± 1.2 years) voluntarily consented to participate in the study conducted by our research team in 2023 and 2024. The skin microbiome analysis involved standardized sampling, DNA isolation, molecular sequencing, and bioinformatic analysis, thus enabling detailed characterization and comparison of the skin microbial community in contact sports athletes and the control group. Results: Our results revealed notable sexual dimorphism in the skin microbiome composition of youth. Males showed a higher relative abundance of bacterial genera associated with nosocomial infections and respiratory diseases, while females had more skin inflammation- and infection-related genera (relative abundances in males vs. in females: Corynebacterium—12.0 vs. 7.2; Luteimonas—4.4. vs. 1.4; Paracoccus—8.8 vs. 5.0; Psychrobacter—6.3 vs. 4.4; Cutibacterium—6.4 vs. 11.4; Kocuria—1.6 vs. 3.9; Micrococcus—5.8 vs. 8.5; Pseudomonas—1.2 vs. 3.4; Streptococcus 3.3 vs. 6.2). We also found skin microbiome differences between athletes and non-athletes in both sexes: wrestlers, who experience frequent skin-to-skin contact and wear less covering sportswear, had microbiome profiles distinct from both kickboxers and non-athletes (relative abundances in athletes vs. in non-athletes: Psychrobacter—7.3 vs. 0.4; Staphylococcus 9.5 vs. 18.5; predominance of genera by sports type: relative abundance of Cutibacterium and Streptococcus was higher in kickboxers, and relative abundance of Acinetobacter, Enhydrobacter, Micrococcus, and Enhydrobacter was higher in wrestlers). Bacteria linked to skin infections (e.g., Aliterella, Arthrobacter, and Empedobacter) were present in around 30% of wrestlers and kickboxers but were absent in the control group. Conclusions: These results underscore the heightened risk of skin infections in contact sports and highlight the importance of regular microbiome monitoring and hygiene protocols among young athletes.