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 cause remains uncertain. The authors aimed to apply the 2bRAD-M technique to characterize the microbiome differences between normal and contracture capsules. METHODS: Ten normal capsules and 10 contractured capsules were used for 2bRAD-M sequencing and corresponding histologic evaluation. By constructing a mouse silicone implant infection model, histologic 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, R. 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 R. pickettii infection caused more infiltration of T cells. CONCLUSIONS: This is the first study to use the 2bRAD-M technique to characterize microbiome differences of relative abundance value between normal and contracture capsules. R. pickettii can recruit more macrophages and T cells to infiltrate. This study provides new etiologic causes of CC and new clinical insights for the prevention and treatment of CC. CLINICAL RELEVANCE STATEMENT: This study identifies R. pickettii as a key pathogen in capsular contracture, demonstrating that it increases capsule thickness, stiffness, and T-cell infiltration. For plastic surgeons, preventing R. pickettii contamination (eg, using hypochlorous acid irrigation) may help reduce contracture risk after breast implant surgery.