Staphylococcus aureus is a versatile pathogen that is able to cause a large diversity of both benign and lethal infections in humans and animals. In order to have adequate information for treatment of S. aureus infections, it is important to understand trends in the antibiotic-resistance patterns as well as clonal identities across geographical regions. This book provides information on antibiotic susceptibility pattern and virulence determinants present in S. aureus isolates from clinical and environmental settings. It also provides an overview of the genotypes of S. aureus clones circulating in health-care settings in Lagos and Ogun States of Nigeria. The characterization of the organism will provide baseline information needed in establishing effective infection control measures in health-care institutions.