Grant is a medical microbiologist and lecturer in communicable disease epidemiology at the Marie Bashir Institute for Infectious Diseases and Biosecurity and School of Public Health, University of Sydney. After completing medicine and medical training at the University of Cambridge he went to Saudi Arabia where he set up a laboratory specialising in pathogen genomics. His PhD was in the use of genomics for public health microbiology and as part of this he led a large worldwide study on TB genomics as well as studies on total drug resistant TB in South Africa. His ongoing research is on the evolution of extensive drug resistance in South Africa, Mongolia and Papua New Guinea. He also has a number of other research programmes on MRSA, enteric pathogens and viral encephalitis.