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.