Thesis Format

Alternative Format

MRSA in the Pandemic Era: Genomic Insights and Implications for Future Preparedness

Caitlin Howard, The University of Western OntarioFollow

Degree

Master of Science

Program

Microbiology and Immunology

Supervisor

Guthrie, Jennifer L.

Abstract

Tracking trends in pathogens like methicillin-resistant Staphylococcus aureus (MRSA) over key time periods is vital for understanding pathogen dynamics and supporting pandemic preparedness. This study used a large urban hospital in Toronto, Ontario, as a pilot site for genomic and bioinformatic analysis of MRSA before and during the pandemic to identify potential changes in circulating strains and resistance profiles. The relative frequency of the dominant clonal complex (CC8) plateaued over the pandemic after years of increases, and overall MRSA genetic diversity decreased, suggesting that pandemic-related movement restrictions may have impacted circulating strains. Increases in plasmid-mediated resistance were observed for key antibiotics such as mupirocin and fusidic acid. Additionally, user-informed MRSA outbreak prototype reports were developed to enhance the communication of genomic data to clinical and public health professionals. These findings provide insights that can inform MRSA surveillance efforts by highlighting the importance of integrating genomic data into routine practice.

Summary for Lay Audience

Methicillin-resistant Staphylococcus aureus (MRSA) is a drug-resistant pathogen that can cause serious and difficult-to-treat infections and has historically been a key focus of healthcare infection control. However, the COVID-19 pandemic shifted priorities in many healthcare facilities, leaving the impact on MRSA largely unknown. Before the pandemic, MRSA infections in Ontario were changing, with an increase in community-acquired strains seen in healthcare settings. This increase plateaued during the pandemic, suggesting that COVID-19 control measures such as hospital visitor restrictions, may have impacted the spread of community-acquired MRSA infections. Additionally, the overall genetic diversity of MRSA strains decreased during the pandemic, potentially related to local lockdowns and travel restrictions.

Increased antibiotic use during the early pandemic, coupled with heightened disinfection efforts, has raised concerns about the acquisition of resistance genes. This research observed changes in resistance mechanisms throughout the pandemic, including an increase in detection of the qacC gene which is associated with tolerance to commonly used disinfectants. This indicates that antimicrobial resistance should be closely monitored during times of increased disinfection and heightened antibiotic usage, as these factors can create selection pressures that favor resistant bacteria.

Furthermore, this research establishes a baseline for future studies to improve scientific communication by prioritizing the needs and understanding of end-users in the creation of genomics-based pathogen reports.

Overall, the findings of this research may help to inform the development of future pandemic preparedness and response programs that will consider the potential effects that infection control and public health measures have on other pathogens. Additionally, this work lays the groundwork for improving MRSA surveillance by including genomic data into routine practice thereby informing public health efforts.

Recommended Citation

Howard, Caitlin, "MRSA in the Pandemic Era: Genomic Insights and Implications for Future Preparedness" (2024). Electronic Thesis and Dissertation Repository. 10698.
https://ir.lib.uwo.ca/etd/10698