Mary graduated in medicine from University College Dublin in 1986. She undertook a Fellowship in Infectious Diseases in Washington University Medical School, St Louise, USA and was appointed Assistant Professor of Medicine there in 1995.
Two years later she returned to Ireland to take up the position of Consultant in Infectious Diseases at Cork University Hospital.
Mary has a research interest in the fields of medical education and infectious diseases. She was the first woman to be appointed Dean of the Medical School in University College Cork and is a member of the scientific advisory group of the European Society of Infectious Diseases and Clinical Microbiology.
Mary has been a ministerial appointment to a number of health service-related national boards. During the pandemic, as well as working on the frontline, she was appointed to the National Public Health Emergency Team, the COVID Advisory Group and the Expert Group on Rapid Testing.
In 2017 Mary was elected President of the Royal College of Physicians of Ireland, the first woman to hold the position since the founding of the College in 1654. She was re-elected for a second three-year term in 2020. In 2019, she received the UCD Alumni award for health.