for females ages 18 years and up (full criteria)
at San Francisco, California
study started
completion around
Principal Investigator
by Merisa Piper
Headshot of Merisa Piper
Merisa Piper



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.

Official 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



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


  1. 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.


Breast Cancer, Breast Cancer Female, Genetic Predisposition to Disease, Post-Surgical Antibiotics, Breast Implant Infections, Breast Microbiome, Breast Reconstruction, Mastectomy, Infections, Breast Neoplasms, Cephalexin


You can join if…

Open to females ages 18 years and up

  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.

You CAN'T join if...

  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


  • UCSF accepting new patients
    San Francisco California 94143 United States

Lead Scientist at UCSF

  • Merisa Piper
    Dr. Merisa L. Piper is a plastic and reconstructive surgeon who specializes in breast reconstruction and general reconstruction, with expertise in all methods. With the goal of restoring appearance after partial or complete breast removal, she focuses particularly on microsurgery and free tissue transfer, using skin, fat and muscle from another part of the body.


accepting new patients
Start Date
Completion Date
University of California, San Francisco
Phase 2 Breast Cancer Research Study
Study Type
Expecting 200 study participants
Last Updated