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Evaluating The Local Microbiome Response To Antibiotic Treatment Regimens In Women Undergoing Mastectomy With Implant-based Reconstruction
Michael Choi, MS1, Aileen Gozali, MD
1, Jacquelyn Knox, MD
1, Nisha Parmeshwar, MD
1, Laura Barnes, MD
2, Merisa Piper, MD
1.
1University of California, San Francisco, San Francisco, CA, USA,
2University of Pennsylvania, Philadelphia, PA, USA.
PURPOSE: Implant-based breast reconstruction (IBR) is plagued by high infection rates, which can cause prosthesis failure and delays to adjuvant treatment. Previous studies have shown association between microbiome perturbation and surgical outcomes, but interactions in the context of IBR are poorly understood. Here, we investigate microbial dynamics following IBR with different antibiotic durations.
METHODS: We designed a two-armed randomized-controlled trial of patients undergoing mastectomy with immediate IBR. Patients received 24 hours or 7 days of postoperative cephalexin. Stool samples were collected pre- and postoperatively at specified time points. Periprosthetic fluid was sampled postoperatively during weekly clinic visits. Samples underwent 16s rRNA sequencing and alignment using the SILVA database. Data was rarified. The Shannon index was used to estimate α diversity, and β diversity was tested using PERMANOVA.
RESULTS: Of the 38 patients (62 breasts) included, 20 patients (32 breasts) and 18 patients (30 breasts) received 24 hours and 7 days of antibiotics, respectively. α diversity showed significant decreases in Shannon Diversity scores between pre- and postoperative stool samples in both arms with increased impact after 7 days of antibiotic treatment (24h p=0.027, 7 days p=0.0026). Patient characteristics were determined to be primary drivers of β diversity (p=0.027). Periprosthetic fluid α diversity was also significantly different between arms (p=0.041).
CONCLUSION: We show that different antibiotic durations significantly impact diversity of the gut and periprosthetic environment. We plan to further investigate patient-specific differences in non-uniform antibiotic response and expand upon these results with a larger patient cohort and outcomes data.
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