Infections after tissue expander breast reconstruction can lead to pain, additional surgeries, and loss of the reconstruction. This study will compare two types of antibiotic carriers used during surgery to help lower the risk of infection. One carrier is a non-absorbable PMMA disc, and the other is an absorbable antibiotic bead. Both release antibiotics directly into the breast pocket after surgery.

About 100 patients will be randomly assigned to receive one of these two carriers at the time of tissue expander placement. After surgery, small samples of fluid around the tissue expander will be collected during routine clinic visits. These samples will be tested to measure how much antibiotic is present over time. The study will also track infections, tissue expander loss, and other complications during the first 90 days after surgery. The goal is to learn how much antibiotic each carrier delivers and whether one method is more effective at preventing infection.

Infection remains a devastating complication in tissue expander-based breast reconstruction, potentially causing patient distress, multiple re-operations, explantation, and the failure of the entire reconstructive process. A promising strategy to reduce this risk involves the local application of antibiotic carriers-materials placed in the surgical pocket that elute high concentrations of antibiotics directly at the site where infections begin. Recent studies have shown that both non-absorbable polymethylmethacrylate (PMMA) discs and absorbable antibiotic beads can significantly lower infection rates. However, the current evidence is limited because all prior studies are retrospective, lack direct comparisons between these carriers, and crucially, have no measurements of the actual antibiotic levels achieved in patients. This gap in knowledge leaves surgeons without clear, evidence-based guidance on which method is superior. This study is a prospective, randomized controlled trial designed to provide that definitive evidence. The investigators will enroll 100 patients undergoing tissue expander breast reconstruction at our institution. During surgery, each participant will be randomly assigned to receive either an antibiotic-impregnated PMMA disc or absorbable antibiotic beads placed in the breast pocket alongside the tissue expander. The study is meticulously designed to eliminate bias, with independent experts blinded to the treatment when assessing outcomes. The primary objective is to conduct a detailed pharmacokinetic analysis, measuring the concentration of vancomycin and tobramycin in the periprosthetic fluid over time. This will be achieved by analyzing seroma fluid aspirated during routine, scheduled post-operative clinic visits. This novel approach will not only provide data on whether the carriers work, but also how they work-how high the antibiotic levels reach, and for how long they remain effective. The secondary objective is to compare critical clinical outcomes, including surgical site infection rates, tissue expander loss, and other complications over a 90-day period. By directly linking precise, local drug exposure data with hard clinical endpoints, this research will for the first time establish a biologic gradient for efficacy and determine the comparative effectiveness of these two infection-prevention strategies.

Inclusion Criteria:

1. Adult females ≥18 years undergoing TE-based breast reconstruction (immediate or delayed).
2. Able to consent and comply with follow-up/aspiration visits.

Exclusion Criteria:

1. Allergy to vancomycin, tobramycin, or PMMA components.
2. CKD stage 4-5 (eGFR <30 mL/min/1.73m²).
3. Chronic immunosuppression (≥10 mg prednisone daily or biologic immunosuppressants).
4. Active systemic infection
5. Pregnancy, planning to become pregnant during the study, or lactation.
6. Lack of capacity to provide consent.
7. Prisoners

Individual participant data will not be shared due to the inclusion of sensitive health information and standardized photographs that cannot be fully de-identified. Data will be used solely for the purposes of this study in accordance with UC Davis IRB approval.