Interactions between coagulase-negative staphylococci and the host

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Mammals are hosts to myriad number of bacteria called the microbiome. Most of these bacteria live in a commensal relationship with us, providing us health, and resistance to pathogenic, or disease-causing, bacteria that we may encounter. My laboratory's research has focused on a group of bacteria known as the staphylococci, which are a group of bacteria made up of approximately 50 species. Most of these species are commensal and do not cause harm, while a handful do have elevated pathogenic potential. The most notorious among these is Staphylococcus aureus which can cause several types of infection and diseases in humans and animals. Our research is centred around understanding the mechanisms by which members of the staphylococci interact with their host, allowing them to survive and thrive on skin and mucosal surfaces which are normally inhospitable to microbes. We examine how these bacteria sense and adapt to their surroundings. These signals include limiting nutrients, host antimicrobials (e.g. fatty acids and peptides), and competing microorganisms. Bacteria that colonize the skin or mucosal membranes of mammals (the host) must be physiologically equipped to survive this inhospitable environment for extended periods. They must also be resistant or tolerant to the host immune system. One of the species of staphylococci, S. lugdunensis, is a noted commensal bacterium. It lives in the nose and can produce an antibiotic that kills S. aureus. Thus, in some circles, this bacterium has been regarded as a probiotic and its use as such has been interrogated. However, its use as a probiotic is contraindicated because of its virulence potential as it can cause infections and sometimes serious. Our research program seeks to identify defining features in this species that distinguish its pathogenic potential. This research program has three aims: Aim1: Define the molecular mechanisms by which S. lugdunensis survives in blood and in immune cells. Aim2: Define the molecular mechanisms by which S. lugdunensis destroys red blood cells and immune cells. Aim3: Define the molecular mechanisms by which S. lugdunensis sticks to host cells or tissues, and how it releases itself so that it may spread to other areas within the host. This discovery-based research program will address important and unique questions concerning key traits of the commensal, yet opportunistic pathogen, S. lugdunensis. The research will provide meaningful and impactful contributions to our understanding of this much understudied bacterium. Along the way, the research program will train many next-generation HQP to become independent thinkers, learners and future leaders. The research, and the HQP thus trained, will have wide-ranging benefits to Canadians. The research is positioned to design and develop better strategies to thwart the spread of antibiotic-resistant bacteria.