Firmicutes and Bacteroidetes in the gut microbiome: a potential link to acne pathogenesis

Context Acne is a chronic inflammatory condition of the pilosebaceous unit that affects up to 90% of adolescents. Aims To investigate the potential relationship between gut microbiota composition, dietary factors, and the development of acne, focusing on the interplay between the Firmicutes and Bacteroidetes phyla, and their impact on acne severity. Settings and design This case–control study was conducted at the Outpatient Clinics of Dermatology, Venereology, and Andrology of Benha University Hospitals. Patients and methods This case–control study was carried out on 60 participants of age more than or equal to 18 years and complaining of moderate to severe acne vulgaris, alongside age-matched and sex-matched healthy volunteers in the Outpatient Clinics of Dermatology, Venereology, and Andrology of Benha University Hospitals. All participants were divided into two equal groups: group I included patients with acne vulgaris, and group II ( n =30) included age-matched and sex-matched healthy volunteers as a control group. Results The best cutoff of Firmicutes/Bacteroidetes ratio in the prediction of severe acne vulgaris is more than or equal to 1.415 with an area under the curve of 0.91 with a sensitivity of 83.3%, specificity of 88.9%, positive predictive value of 45.5%, negative predictive value of 98%, and an overall accuracy of 88.3% ( P =0.001). The best cutoff of Firmicutes in the prediction of severe acne is more than or equal to 0.56 with an area under the curve of 0.846 with a sensitivity of 100%, specificity of 75.9%, positive predictive value of 31.6%, negative predictive value of 100%, and an overall accuracy of 78.3% ( P =0.006). There were statistically significant positive correlations between Global Acne Grading System and frequency of intake of fries and vegetables/fruits. Conclusions A clear association between acne vulgaris and both dietary habits and gut microbiota composition.