Dr. Thomas F. O'Brien was a noted American epidemiologist, associate professor at the Harvard Medical School, and director of the infectious disease department at Brigham & Women's Hospital in Boston. He was also known for being the husband of noted attorney Ruth Reardon O'Brien and father of entertainer Conan O'Brien.

According to his Harvard biography:

Following graduation from Harvard Medical School, Thomas O'Brien was a medical resident for two years at Peter Bent Brigham Hospital, Boston, a Harvard University Mosley Fellow for one year at Cambridge University, England, an active duty Captain in the U.S. Army Medical Corps for two years, and a research fellow in the Department of Microbiology at Harvard Medical School for another two years before a final year as a senior medical resident at Peter Bent Brigham Hospital. Following this he was appointed Director of the Division of Infectious Diseases and Director of the Microbiology Laboratory at that hospital, in which he now serves as Senior Physician in the Division of Infectious Diseases and Medical Director of the Microbiology Laboratory. His dual role as clinician consulting on complicated infections and director of a laboratory identifying the microbes causing the infections and measuring their resistance to antibiotics prompted Dr. O'Brien to focus on the problems of antibiotic resistance and especially their molecular basis and epidemiology. This work led to the designation of his laboratory as World Health Organization Collaborating Center for the Surveillance of Antimicrobial Resistance and the development of software called WHONET, which now links laboratories in resistance surveillance networks in more than eighty countries. On May 5, 2005 he joined the committee of a project called New Directions in the Study of Antimicrobial Therapeutics: New Classes of Antimicrobials.

Dr. O'Brien earned a full scholarship to Harvard Medical School, receiving his MD in 1954. He continuously published and conducted major medical research from 1959. His research interests included anti-bacterial agents, cross infection, microbial drug resistance, enterobacteriaceae, R-factors, world health, and bacteria.

Per his obituary:

"Dr. O’Brien was a Resident, Department of Medicine, Peter Bent Brigham Hospital, Boston, MA (1954-56), a Mosley Traveling Fellow in Immunology, Cambridge University, United Kingdom (1956), Captain, U.S. Army Medical Corps, Brook Army Medical Center, San Antonio, TX (1957-59), and Research Fellow, Department of Microbiology, Harvard Medical School (1959-1961). During the following thirty years, Dr. O’Brien was Director of the Division of Infectious Diseases and Director of the Microbiology Laboratory, Peter Bent Brigham Hospital (later Brigham & Women’s Hospital), Boston, MA (1962-1992) and served as an Associate Professor, Harvard Medical School."

Sources

• http://researchfaculty.brighamandwomens.org/BRIProfile.aspx?id=4769
• https://www.bellodeafuneralhome.com/obituary/thomas-obrien-md