Characterizing MRSA Plasmids, Antibiotic Resistance, and Disinfectant Tolerance Across the COVID-19 Pandemic

Methicillin-resistant Staphylococcus aureus, or simply MRSA, is a type of bacteria that can cause serious and potentially life-threatening infections. It is a major cause of hospital-acquired infections worldwide and a significant public health concern in Canada. Often resistant to multiple antibiotics, MRSA infections are difficult to treat. One factor that helps MRSA survive in healthcare settings is the presence of plasmids - small, circular pieces of DNA that can move between bacteria and carry genes that enable resistance to antibiotics or lower its susceptibility to disinfectants. During the COVID-19 pandemic, hospitals greatly increased their use of disinfectants to prevent the spread of infections. This has raised important questions about whether increased disinfectant use inadvertently created conditions that favored MRSA strains carrying disinfectant-tolerance genes, which are often found on plasmids alongside antibiotic resistance genes, making these strains particularly concerning. This study will analyze more than 1,500 MRSA isolates collected from Ontario hospitals before, during, and after the COVID-19 pandemic. Through advanced DNA sequencing and laboratory testing, MRSA plasmids will be characterized, antibiotic resistance and biocide tolerance genes will be identified, and it will be determined whether these genetic features changed during this period. The findings are expected to improve understanding of the genetic traits that may help MRSA survive in heavily disinfected environments. These insights are urgently needed to strengthen infection-control strategies and support the effective, sustainable use of antibiotics and disinfectants in healthcare settings.