Axillary and Gut Microbiota Characteristics in Axillary Bromhidrosis Patients and the Effect of Microwave Therapy: A Case-Control Study
Introduction: Axillary bromhidrosis is characterized by excessive sweat gland activity and foul body odor, significantly affecting patients' psychological well-being and social interactions. Methods: This study recruited 30 axillary bromhidrosis patients and 30 healthy controls, collecting sweat and stool samples for microbiome analysis. Among the patients, 8 patients received microwave therapy, collecting pre-and post-treatment samples for microbiome analysis. Results: The axillary microbiota of patients showed significant differences compared to healthy controls, particularly with increased abundance of odor-causing bacteria such as Staphylococcus and related species (Staphylococcus hominis, Staphylococcus haemolyticus) (LDA > 3, P < 0.05). While the gut microbiota composition showed no significant changes, but LEfSe analysis revealed that SCFAs-producing bacteria (Bacteroides stercoris, Phocaeicola massiliensis, and Phocaeicola vulgatus) was significantly elevated (LDA > 3, P < 0.05), indicating that the abundance changes of SCFAs-producing bacteria may be associated with axillary odor production through the regulation of metabolic processes. Correlation analysis revealed positive correlations between axillary odor-producing genera (Staphylococcus, Peptoniphilus, Anaerococcus) and gut SCFAs-producing genera (Roseburia, Blautia, Clostridium), suggesting a bidirectional microbiota network through gut-derived butyrate production and immune modulation (P < 0.05). However, further experimentals are required to confirm the causal relationship. Furthermore, microwave therapy significantly altered axillary microbiota diversity, potentially alleviating axillary odor by inhibiting odor-producing bacteria (Staphylococcus) (LDA > 3, P < 0.05), while exerting minimal impact on the gut microbiota. KEGG pathway enrichment analysis revealed significant metabolic activity changes in lipid, carbohydrate, sulfur, and amino acid metabolism pathways. Conclusion: This study is the first to demonstrate the interrelationship between the axillary and gut microbiota in axillary bromhidrosis patients, showing a link between gut-derived butyrate production and axillary odor. These findings offer new insights into the microbiological mechanisms underlying axillary bromhidrosis and identify potential microbial targets for future gut-based systemic treatments.