PFGE diversity within the methicillin-resistant Staphylococcus aureus clonal lineage ST398

Area of Science:

• Veterinary Microbiology
• Infectious Diseases
• Molecular Epidemiology

Background:

• Livestock are a reservoir for methicillin-resistant Staphylococcus aureus (MRSA), particularly ST398.
• Standard SmaI pulsed-field gel electrophoresis (PFGE) is ineffective for typing these MRSA isolates.
• A novel PFGE method is needed to study MRSA ST398 transmission and outbreaks.

Purpose of the Study:

• To optimize and evaluate a new PFGE method using Cfr9I for typing MRSA ST398.
• To assess the discriminatory power of Cfr9I PFGE compared to existing methods.
• To investigate MRSA ST398 transmission dynamics and confirm outbreaks.

Main Methods:

• Optimization and evaluation of Cfr9I PFGE protocol.
• Comparison of Cfr9I PFGE with spa-typing and multi-locus sequence typing (MLST).
• Analysis of MRSA ST398 isolate banding patterns against a large database.

Main Results:

• Cfr9I PFGE successfully generated clear, reproducible patterns for previously non-typeable MRSA (NT(SmaI)-MRSA) isolates.
• Cfr9I PFGE demonstrated higher diversity within ST398 isolates than spa-typing or MLST.
• Transmission among veterinarians and an outbreak in a residential care facility were confirmed using Cfr9I PFGE.

Conclusions:

• The adjusted Cfr9I PFGE is a valuable tool for selecting distinct ST398 isolates for further research.
• This PFGE protocol is easily implementable in laboratories with existing PFGE facilities.
• Cfr9I PFGE enhances the study of the ST398 clonal lineage and MRSA epidemiology.