While there are recognized health benefits from human interaction with companion animals, there is also increasing popular concern that pets can serve as reservoirs of zoonotic bacteria. In the community, Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) infections represent a critical and rapidly growing public health issue. Children represent the fastest growing segment of the population affected by MRSA. However, few scientific studies have directly addressed whether pet dogs play an important role in the transmission of SA and MRSA at the household level. The overall aim of this project is to determine the impact of pet ownership on children by measuring SA and MRSA colonization which is the first step in the infectious process. This study will: 1) determine the prevalence of SA and MRSA colonization in a community-based sample of children and family members with pet dogs and compare this to a sample of non-pet owning household members, 2) examine whether specific types of human-animal interactions are associated with colonization, and 3) examine the relatedness of recovered strains from children, family members, and their pet dogs using molecular methods (PFGE and SCCmec typing). Our interdisciplinary team will identify specific human factors, animal factors, social environments (i.e., human-animal interactions), and physical environmental characteristics that may be associated with increased colonization risk. Given the increasing evidence of the health benefits of human-animal interaction, it is important for future studies to consider potential health risks f pet ownership - particularly among children who are susceptible to infection due to impaired immune function. This study will contribute to our knowledge of how pets in the home potentially impact children's health and could help identify measures which would reduce the risk of transmission of SA and MRSA in the home.