SURVEILLANCE OF ANTIMICROBIAL SUSCEPTIBILITY PATTERNS AMONG PATHOGENS ISOLATED IN PUBLIC SECTOR HOSPITALS ASSOCIATED WITH ACADEMIC INSTITUTIONS IN SOUTH AFRICA Peter Suwirakwenda Nyasulu A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, In fulfilment of the requirements for the degree of Doctor of Philosophy in the area of Infectious Diseases Epidemiology Johannesburg, November 30, 2014