Professor Gillespie was appointed at the Foundation Sir James Black Chair of Medicine at the University of St Andrews in 2010. His main research is to try to improve tuberculosis treatment and has published more than 200 papers in peer reviewed journals. His work includes being the coordinating investigator for TB Alliance trials including REMoxTB, the first regulatory pivotal trial of two treatment-shortening regimens and the STAND trial. His current work in St Andrews includes research developing novel diagnostic assays including a molecular bacterial load assay that can quantify the number of live organisms in less than four hours and innovative drug susceptibility tests that speed the time to result more than 60 times. He works closely with colleagues in applied mathematics and computer science to develop innovative agent based and network models of tuberculosis treatment. He has developed a range of tools to determine the phenotypically antibiotic resistant cell state of M tuberculosis cells that may open new avenues for better treatment.