Pathogenesis of Staphylococcus aureus
Why study Staphylococcus aureus?
S. aureus is capable of causing numerous types of infections in humans that range from mild to serious. Indeed, S. aureus can cause minor skin infections such as boils or it can cause more serious infections that result in clinical manifestations such as endocarditis, osteomyelitis, arthritis, septicemia, and toxic shock syndrome, among others, as well as infections of surgical wounds. What is more, S. aureus is known as one of the so-called superbugs, because of the pathogenic nature of the bacterium combined with the fact that it frequently acquires resistance to many currently used antibiotics. Methicillin resistant S. aureus, or MRSA, is one of the most notorious pathogens in the hospital environment and the spread of community acquired MRSA is now becoming prevalent, especially among sports teams. Strains of S. aureus that are resistant to the so-called last resort antibiotic, vancomycin, called VISA or VRSA, are now being isolated.
1. Mechanisms of Iron Acquisition in Staphylococcus aureus
One major focus of our research is directed towards developing an understanding of how the bacterium Staphylococcus aureus acquires iron. There are several project areas under study in this general theme and that would be exciting for prospective graduate students and postdoctoral fellows to engage in.
Why Study Iron?
You might ask "What's so important about iron?". Well, for our survival, we all need iron. This is because the unique properties of this metal allow it to provide an essential electron donor-acceptor functions to many important biological reactions in organisms ranging from bacteria to humans. However, even though iron is so essential and is one of the most abundant elements found on earth, acquiring sufficient quantities of iron is complicated. Indeed, iron is frequently a growth limiting nutrient to many organisms because of its tendency to be extremely insoluble under aerobic conditions. To counteract this problem, the majority of microorganisms have specialized mechanisms for iron acquisition. The research focus of this laboratory is the study of specialized iron uptake mechanisms that are used by bacteria to successfully colonize the host and cause infection. One such system invokes high affinity iron chelators, termed siderophores, which are excreted from the bacterial cell and, following chelation of iron, are internalized via cell surface receptor/binding proteins. Alternatively, some bacterial pathogens express receptors that directly bind host iron complexes, such as haemoglobin and heme, as a means to acquire host iron. S. aureus possesses both siderophore and non-siderophore-mediated iron acquisition mechanisms, indicating that this bacterium is highly versatile insofar as iron acquisition is concerned. Since iron is essential for the survival of S. aureus, targeting or inhibiting mechanisms of iron acquisition as a means to prevent colonization or methods to clear or prevent staph infections are exciting avenues of research in the fight against drug resistant pathogens such as S. aureus.
2. Immunobiology of Superantigens
In collaboration with Drs. Madrenas, McCormick, Haeryfar and Cairns, we have formed a multidisciplinary research group to study the immunobiology of superantigens. If you are interested in joining this multidisciplinary superantigen research group, please feel free to contact any one of us.
