Polymicrobial infections are some of the most financially demanding issues in the healthcare system, requiring over $25 billion in treatment annually in the United States alone. This results from their increased virulence, infectivity, and tolerance of common antimicrobial treatments, part of a process termed synergy. While interactions between bacteria have been appreciated for decades, we do not completely understand the exact mechanisms for how these organisms interact within the infection itself. Furthermore, questions remain about how these interactions depend on local microbes, on the environment of their host, or on spatial arrangement in the wound. Here, we sought to identify and understand novel interactions between Staphylococcus aureus and Streptococcus agalactiae (Group B Streptococcus, GBS) in a chronic wound environment. To accomplish this, we assessed tolerance to various antibiotics of each organism individually and in co-culture in our in vitro wound models. Furthermore, we sought to understand how a diabetes mellitus type II environment impacted interactions between these microbes by evaluating how a hyperglycemic environment altered antibiotic tolerance. Our preliminary results suggest that S. aureus has increased tolerance to specific antibiotics when cocultured in vitro with S. agalactiae and saw an increase in tolerance when grown in our wound models. Our data also shows that S. agalactiae has increased tolerance to specific antibiotics when co-cultured in wound models individually and decreased tolerance when grown with S. aureus. These results suggest a heightened importance of the environment on the role of antibiotic tolerance development in microorganisms when grown together, and further tests are needed to determine the exact mechanisms by which the environment alters the physiology of these two species. These investigations could be essential in producing more effective treatment strategies and hindering the progression of chronic wounds.

University Libraries Undergraduate Research Award