Ralstonia pickettii - The Potential and Substantial Impact in Capsular Contracture: Insights from 2bRAD-M Analysis and Murine Model

Background: Capsular contracture (CC) is one of the most common complications in augmentation mammaplasty with breast implant, but its etiology remains uncertain. We aimed to apply the 2bRAD-M technique to characterize the microbiome differences between normal and contracture capsules. Methods: 10 normal capsules and 10 contractured capsules were used for 2bRAD-M sequencing and corresponding histological evaluation. By constructing a mouse silicone implant infection model, histological staining was used to verify the influence of different microorganisms identified in sequencing results. Results: Histologic evaluation of patient samples revealed a marked increase in the thickness and stiffness of contracture capsules, along with increased infiltration of macrophages and T cells. Through 2bRAD-M sequencing, we found that the microbial composition of contracture capsules was significantly different from that of normal capsules, with the most significant difference of relative abundance value in Ralstonia pickettii . In vivo , Ralstonia pickettii could significantly increase the thickness, collagen content, and hardness of the capsules, which was more effective than the combined infection with Staphylococcus epidermidis and Cutibacterium acnes . Immunofluorescence results showed both bacterial infections caused increased infiltration of macrophages and T cells, and Ralstonia pickettii infection caused more infiltration of T cells. Conclusion: This is the first study to use 2bRAD-M technique to characterize microbiome differences of relative abundance value between normal and contracture capsules. Ralstonia pickettii can recruit more macrophages and T cells to infiltrate. This study provides new etiological causes of capsular contracture and new clinical insights for the prevention and treatment of capsular contracture.