Phyllis Margaret Rountree was a leading Australian microbiologist who became an international authority on the typing of bacteriophages, particularly Staphylococcus aureus (Golden Staph).

She graduated with a MSc from the University of Melbourne in 1931, and worked a research assistant with Frank Macfarlane Burnet from 1934-1935. After further study in London, Rountree began work as Research Bacteriologist at the Royal Prince Alfred Hospital, Sydney, in 1944, becoming Senior Bacteriologist in 1961. Her work centered around investigation of the Staphylococcus aureus (Golden Staph) bacteria. Her career also included research into soil salination; botulism in the Second World War; trachoma among Central Australian Aborigines; wound infections and antibiotic resistance. From 1971, Rountree held a position as Honorary Research Associate in Medical Microbiology at the University of New South Wales.