Phoenix, Arizona


Orenstein.Robert@mayo.edu Clinical Profile


The research of Robert Orenstein, D.O., is focused on the prevention and management of health care-acquired infections. With the Mayo Clinic Infection Prevention and Control team, he has helped design systems for surveillance of Clostridium difficile (C. difficile) infection and designed interventions to reduce transmission of C. difficile infections in the hospital environment.

In collaboration with Mayo Clinic gastroenterologists, Dr. Orenstein has studied risks for transmission of C. difficile in the community. Dr. Orenstein's team has been responsible for diffusing these best practices across Mayo Clinic's campuses and assisting other health care institutions and health departments with implementing these best practices.

Additionally, his team at Mayo Clinic in Arizona focuses on providing fecal microbiota transplantation for patients with relapsing C. difficile disease.

Focus areas

  • Prevention of health care-acquired C. difficile infection
  • Treatment of complicated infections due to C. difficile
  • Understanding the microbiome and its role in fecal microbiota therapy
  • Clinical trials of new therapeutics for C. difficile infection

Significance to patient care

Dr. Orenstein's work on prevention has led to significant reductions in health care-associated infections occurring at Mayo Clinic facilities. His program in fecal microbiota transplantation offers patients relief from chronic relapsing C. difficile infection.

Understanding the mechanisms by which these treatments work should help lead to solutions and preventive measures for the future.


Primary Appointment

  1. Consultant, Division of Infectious Diseases, Department of Internal Medicine

Administrative Appointment

  1. Chair, Division of Infectious Diseases, Department of Internal Medicine

Academic Rank

  1. Professor of Medicine


  1. Fellow - Infectious Diseases Medical College of Virginia, Virginia Commonwealth University
  2. Resident - Internal Medicine Geisinger Medical Center
  3. Internship - Rotating Osteopathic Internship Botsford General Hospital
  4. Doctor of Osteopathic Medicine - Doctor of Osteopathic Medicine and Surgery College of Osteopathic Medicine, Des Moines University
  5. Graduate School - Graduate studies in Biomedical Engineering Worcester Polytechnic Institute
  6. BS - Biochemistry Trinity College

Clinical Studies

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