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NCT Number: NCT05020574

Microbiome and Association With Implant Infections

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.

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Key information

Age range

18 year and older

Sex eligibility

Female

Study type

Interventional

Phase

Phase 2

Primary location

University of California, San Francisco

San Francisco, California, 94143, United States

Location status: Recruiting

Location contact

Laura Barnes, MD

CONTACT

[email protected]

415-502-1259

Laura Barnes, MD

SUB_INVESTIGATOR

Merisa Piper, MD

PRINCIPAL_INVESTIGATOR

Michael Campbell, PhD

SUB_INVESTIGATOR

CONTACT

[email protected]

877-827-3222

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

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

Exclusion criteria

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

Treatment and study plan

Cephalexin

Drug

Given orally (PO)

Other names: Keflex

Primary outcomes

  1. Proportion of tissue samples obtained successfully over time

    Time frame: 90 days

    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.

  2. Proportion of aspirate samples obtained successfully overall

    Time frame: 90 days

    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.

  3. Proportion of tissue samples successfully producing microbiome data

    Time frame: 90 days

    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.

  4. Proportion of aspirate samples successfully producing microbiome data

    Time frame: 90 days

    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.

  5. Proportion of any samples successfully producing microbiome data

    Time frame: 90 days

    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.

  6. Correlation of the change in breast microbiome over time with total duration of antibiotics (Cohort A only)

    Time frame: 90 days

    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.

Secondary outcomes

  1. Proportion of participants with post-operative infection

    Time frame: 90 days

    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.

  2. Shannon Diversity Index Score for species of microbiome

    Time frame: 90 days

    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.

  3. Number of overall identified microbes

    Time frame: 90 days

    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

Study contacts

Contact information is provided by the study sponsor or research team.

Laura Barnes, MD

CONTACT

[email protected]

(415) 502-1259

Sponsors and collaborators

Lead sponsor

University of California, San Francisco

Other

Collaborators

  • The Plastic Surgery Foundation

Registry information

Official study title

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

Important dates

Study start
2021
Primary completion
2026
Study completion
2026
First posted
Aug 25, 2021
Registry last updated
Mar 18, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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