Methicillin-resistant Staphylococcus aureus (MRSA) is a major healthcare threat due to its antibiotic resistance. This study examined the genomic evolution of the ST228 SCCmec-I MRSA strain after a hospital outbreak a decade ago, addressing a key question: What happens to epidemic bacteria once an outbreak is controlled? Over 10 years, we collected and sequenced MRSA isolates from patients, comparing outbreak strains to later samples. The epidemic strain underwent significant genetic changes, including:
- Loss of resistance and virulence genes
- Acquisition of new genes favoring long-term survival over rapid spread
Using GWAS and machine learning, we identified genetic markers linked to the strain’s declining epidemic potential. This decline coincided with enhanced infection control measures, suggesting a combined effect of human intervention and bacterial adaptation.
Key findings:
- Rigorous infection control can reduce the spread of dangerous bacteria.
- Pathogens adapt to new environments, even under heightened controls.
- The study provides a roadmap for monitoring and preventing outbreaks, offering insights critical to combating antibiotic resistance.
For more information, see the published paper.
