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About our Research

Research in the Geoghegan lab focuses on the bacterial pathogen Staphylococcus aureus. Our main interest is in understanding the interaction between S. aureus and the human host during colonisation and infection through the study of bacterial factors that promote interaction with human cells and tissues and allow persistence in the human body.

A major focus is on understanding how S. aureus establishes itself in two medically important habitats. The human nose is the main site of colonisation in healthy humans and our research aims to further knowledge of the fundamental mechanisms used by S. aureus to persist at this site. This is important because colonisation is a major risk factor for invasive infection. The second habitat we investigate is the skin of atopic dermatitis (AD) patients. AD skin lesions are particularly susceptible to bacterial colonisation and infection and we are exploring this niche to gain new insights into the host-pathogen interaction. We are also interested in understanding how molecules produced by bacterial residents of the human microbiota influence nasal colonisation and skin infection.

We study the mechanistic basis of biofilm formation in methicillin resistant S. aureus (MRSA). By growing as biofilm communities on catheters, heart valves and artificial joints, bacteria avoid being killed by antibiotics and the human immune system. Our group are investigating the molecular basis of protein-mediated biofilm formation in MRSA. We have found that it is possible to prevent staphylococci from building biofilms by targeting the protein linkages that hold the bacteria together and the interactions that facilitate adherence to surfaces. These findings offer new opportunities for the development of compounds to prevent biofilm formation by staphylococci.

A major research interest in the Geoghegan lab is in understanding how copper tolerance genes contribute to the ability of MRSA to colonise and persist during human infection. We are investigating how copper tolerance genes carried on mobile genetic elements and allow MRSA to resist the antibacterial effects of copper also help the bacteria to withstand killing by human immune cells. This is related to our interest in antibiotic resistance in pathogenic bacteria and the link between metal and antibiotic use in food-production animals and antibiotic resistance in human pathogens.

Read more here about our research here: https://www.tcd.ie/provost/review/2018/04.5.TCD_Research_Case_Studies_Joan_Geoghegan.pdf

Biofilm formation by Staphylococcus aureus . A) The bacteria (gold) attach to a surface inside the body (such as human cells, shown here) during the initial stages of infection. Once they attach, the bacteria begin to grow and link together. They build large accumulations of bacteria known as biofilms. Precisely targeting the binding sites on bacterial proteins can prevent attachment to the host surface (B) or prevent linkages from forming during biofilm formation (C). Group Members 2020