Microbiome and Association With Implant Infections

Microbiome and Association With Implant Infections: Investigating the Impact of Antibiotics on the Gut and Breast Microbiomes Post-mastectomy With Implant-based Breast Reconstruction

The most common tissue expander-related infections are from Staphylococcus and Pseudomonas species. In addition, from breast tissue microbiome studies, Staphylococcus and Pseudomonas show variable abundance across samples. The investigator hypothesizes that participants undergoing mastectomy with high initial abundance of Staphylococcus and/or Pseudomonas are more likely to develop subsequent tissue expander-related infections from these respective organisms.

Study Overview

• Status: Recruiting
• Conditions: Breast Cancer; Genetic Predisposition to Disease; Breast Cancer Female
• Intervention / Treatment: Drug: Cephalexin

Detailed Description

PRIMARY OBJECTIVE:

I. To determine the feasibility of breast microbiome sampling using the study techniques

SECONDARY OBJECTIVES:

I. To define the differences in the gut and breast microbiomes between participants undergoing mastectomy with implant-based reconstruction who develop post-operative implant infection and those who do not.

II. To determine the effects of post-operative antibiotics on the gut and breast microbiomes after mastectomy with implant-based reconstruction.

OUTLINE: Participants are randomized to 1 of 2 cohorts.

COHORT A: Participants receive postoperative antibiotics to take for at least 7 days post-operatively.

COHORT B: Participants receive no antibiotics post-operatively in the absence of clinical evidence of infection.

Participants are followed up for 90 days.

• Study Type: Interventional
• Enrollment (Estimated): 200
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Laura Barnes, MD; Phone Number: (415) 502-1259; Email: Laura.Barnes@ucsf.edu

Study Locations

• United States
  • California
    • San Francisco, California, United States, 94143
      • Recruiting
      • University of California, San Francisco
      • Contact: Laura Barnes, MD; Phone Number: 415-502-1259; Email: Laura.Barnes@ucsf.edu
      • Principal Investigator: Merisa Piper, MD
      • Sub-Investigator: Laura Barnes, MD
      • Sub-Investigator: Michael Campbell, PhD
      • Contact: Phone Number: 877-827-3222; Email: cancertrials@ucsf.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Patients must have histologically confirmed breast malignancy OR genetic predisposition to breast cancer.
2. Age >= 18 years
3. Scheduled to undergo mastectomy with the immediate placement of tissue expanders or implant placement
4. Ability to understand a written informed consent document, and the willingness to sign it
5. At least 4 weeks post-completion of chemotherapy or radiation therapy.

Exclusion Criteria:

1. Any significant medical condition or laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study
2. Pregnant or breastfeeding
3. Patients who have taken antibiotics within 90 days of the consent date
4. Patients who have taken probiotics within 90 days of the consent date
5. Patients who have a documented or reported allergic reaction to the outlined antibiotics to be used in this study
6. Male patients

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Supportive Care
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cohort A: Standard antibiotics; Receive standard pre-incision antibiotics and 24-hour perioperative antibiotics - Prescribed standard postoperative antibiotics to take for at least 7 days post-operatively	Drug: Cephalexin; Given orally (PO); Other Names: Keflex
No Intervention: Cohort B: No antibiotics; Receive standard pre-incision antibiotics and 24-hour perioperative antibiotics - No antibiotics post-operatively, unless patient develops clinical evidence of infection

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of tissue samples obtained successfully over time	The feasibility of success in obtaining samples from breast tissue will be measured as a binary outcome (successful or not successful) over time (intra-operatively, week 1, week 2, week 3, and week 4). The investigators will assess and document success in obtaining a tissue sample immediately at the time of sampling of each participant.	90 days
Proportion of aspirate samples obtained successfully overall	The feasibility of success in obtaining samples from the tissue expander aspiration ports will be measured as a binary outcome (successful or not successful) over time (intra-operatively, week 1, week 2, week 3, and week 4). The investigators will assess and document success in obtaining a aspirate sample immediately at the time of sampling of each participant.	90 days
Proportion of tissue samples successfully producing microbiome data	Feasibility based off of the success rates in producing microbiome data from tissue samples in each patient will be measured as a binary outcome (successful or not successful) and will be reported.	90 days
Proportion of aspirate samples successfully producing microbiome data	Feasibility based off of the success rates in producing microbiome data from tissue samples in each patient will be measured as a binary outcome (successful or not successful) and will be reported.	90 days
Proportion of any samples successfully producing microbiome data	Feasibility based off of the success rates in producing microbiome data from tissue or aspirate samples in each patient will be measured as a binary outcome (successful or not successful) and will be reported.	90 days
Correlation of the change in breast microbiome over time with total duration of antibiotics (Cohort A only)	The investigators will analyze the microbiomes between groups, between microbiome environments (gut v. breast, inter-individual). The correlate of change in breast microbiome over time will be compared to the total duration of antibiotics for Cohort A only. The measure of association ranges from +1 to -1, with a value of zero equal to no association.	90 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of participants with post-operative infection	Safety will be assessed by clinically assessing for signs of post-operative infection in each patient at each clinic visit. A post-operative infection is defined by clinical assessment of findings of surgical site erythema, tenderness, edema, and/or purulent drainage +/- fever. Proportion of participants with clinically diagnosed infection will be reported for each group and final diagnosis for analyses will be binary; a participant will either have a post-operative infection in the 90 day post-operative period or not have a post-operative infection in the 90 day post-operative period.	90 days
Shannon Diversity Index Score for species of microbiome	Alpha diversity will be evaluated for species richness by number of operational taxonomic units and for evenness using the Shannon Index. The Shannon diversity index (H) is an index that is commonly used to characterize species diversity in a community and accounts for both abundance and evenness of the species present. The proportion of species (i) relative to the total number of species (pi) is calculated, and then multiplied by the natural logarithm of this proportion (lnpi). The resulting product is summed across species, and multiplied by -1. Shannon's equitability (EH) can be calculated by dividing H by Hmax (here Hmax = lnS). Equitability assumes a value between 0 and 1 with 1 being complete evenness and the overall index score is represented by a percentage of the species.	90 days
Number of overall identified microbes	The investigators will evaluate microbial composition by grouping identified microbes into operational taxonomic units at the species, genera and phyla levels and will compare the relative abundances of these microbes between groups at the species, gene	90 days

Collaborators and Investigators

• Sponsor: University of California, San Francisco
• Collaborators: The Plastic Surgery Foundation
• Investigators: Principal Investigator: Merisa Piper, MD, University of California, San Francisco

Study record dates

Study Major Dates

• Study Start (Actual): September 28, 2021
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: August 20, 2021
• First Submitted That Met QC Criteria: August 20, 2021
• First Posted (Actual): August 25, 2021

Study Record Updates

• Last Update Posted (Actual): March 18, 2026
• Last Update Submitted That Met QC Criteria: March 16, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Mastectomy; Breast Reconstruction; Post-Surgical Antibiotics; Breast Implant Infections; Breast Microbiome
• Additional Relevant MeSH Terms: Pathologic Processes; Neoplasms by Site; Neoplasms; Disease Attributes; Skin Diseases; Breast Diseases; Disease Susceptibility; Pathological Conditions, Signs and Symptoms; Skin and Connective Tissue Diseases; Breast Neoplasms; Genetic Predisposition to Disease; Sulfur Compounds; Organic Chemicals; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Amides; beta-Lactams; Lactams; Cephalosporins; Thiazines; Cephalexin
• Other Study ID Numbers: 217510; NCI-2021-08985 (Registry Identifier: NCI Clinical Trials Reporting Program (CTRP))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes