Pharmacokinetics of Locally Applied Antibiotic Prophylaxis for Implant-Based Breast Reconstruction.

Importance: Antibiotic irrigation of breast implants is widely used internationally, but no clinical study has investigated the pharmacokinetics of antibiotic prophylaxis in the breast implant pocket. Objectives: To evaluate how long locally applied gentamicin, cefazolin, and vancomycin concentrations in the implant pocket remain above the minimum inhibitory concentration (MIC) for the most common bacterial infections and to measure systemic uptake. Design, Setting, and Participants: This prospective cohort study was performed at the Department of Plastic Surgery and Burns Treatment, Rigshospitalet, Copenhagen, Denmark, between October 25, 2021, and September 22, 2022, among 40 patients undergoing implant-based breast reconstruction who were part of the ongoing BREAST-AB trial (Prophylactic Treatment of Breast Implants With a Solution of Gentamicin, Vancomycin and Cefazolin Antibiotics for Women Undergoing Breast Reconstructive Surgery: a Randomized Controlled Trial). Patients were randomized to receive locally applied gentamicin, cefazolin, and vancomycin or placebo. Samples were obtained from the surgical breast drain and blood up to 10 days postoperatively. Exposures: The breast implant and the implant pocket were irrigated with 160 µg/mL of gentamicin, 2000 µg/mL of cefazolin, and 2000 µg/mL of vancomycin in a 200-mL saline solution. Main Outcomes and Measures: The primary outcome was the duration of antibiotic concentrations above the MIC breakpoint for Staphylococcus aureus according to the Clinical and Laboratory Standards Institute: gentamicin, 4 µg/mL; cefazolin, 2 µg/mL; and vancomycin, 2 µg/mL. Secondary outcomes included the time above the MIC for Pseudomonas aeruginosa and other relevant bacteria, as well as systemic uptake. Results: The study included 40 patients (median age, 44.6 years [IQR, 38.3-51.4 years]; median body mass index, 23.9 [IQR, 21.7-25.9]) with a median number of 3 drain samples (range, 1-10 drain samples) and 2 blood samples (range, 0-6 blood samples). Vancomycin and cefazolin remained above the MIC for S aureus significantly longer than gentamicin (gentamicin, 0.9 days [95% CI, 0.5-1.2 days] for blood samples vs 6.9 days [95% CI, 2.9 to 10.9 days] for vancomycin [P = .02] vs 3.7 days [95% CI, 2.2-5.2 days] for cefazolin [P = .002]). The gentamicin level remained above the MIC for P aeruginosa for 1.3 days (95% CI, 1.0-1.5 days). Only cefazolin was detectable in blood samples, albeit in very low concentrations (median concentration, 0.04 µg/mL [range, 0.007-0.1 µg/mL]). Conclusions and Relevance: This study suggests that patients treated with triple-antibiotic implant irrigation during breast reconstruction receive adequate prophylaxis for S aureus and other common implant-associated, gram-positive bacteria. However, the protection against P aeruginosa may be inadequate.

Antibiotic implant irrigation and deep infection: A retrospective study of 1508 patients undergoing breast reconstruction with implants.

BACKGROUND: Antibiotic implant irrigation is increasingly used to prevent deep infection after implant-based breast reconstruction. However, there is limited evidence of the clinical effect. In this study, we compare the risk of a deep infection in a Danish population of women who either received antibiotic implant irrigation with gentamycin or vancomycin, or no irrigation. METHODS: We retrospectively reviewed consecutive patients undergoing all types of breast reconstruction with implants at Rigshospitalet and Herlev Hospital, Denmark, in 2010-2019. Logistic regression was used to compare the risk of deep infection between no irrigation and irrigation with gentamicin or vancomycin, and to account for the difference in risk between patient subgroups and risk factors. RESULTS: We included 1508 patients who received antibiotic irrigation with gentamicin (500 patients), vancomycin (304 patients) or no irrigation (704 patients). The univariable risk analysis showed a significant decreased risk of deep infection using gentamicin irrigation compared with no irrigation (OR 0.58, p<0.05). However, when adjusting for risk factors for infection, there was no significant decrease in the risk of infection when using gentamicin (OR 0.90, p=0.71) or vancomycin (OR 1.0, p=0.99) compared with the control group. CONCLUSIONS: We found no significant effect of using antibiotic implant irrigation after isolating it from risk factors for deep infection. However, due to the limitations of the study, we cannot conclude that there is no effect of antibiotic implant irrigation. There is a need for a randomized, placebo-controlled trial to investigate the effect, and potential side-effects, of antibiotic implant irrigation.