Molecular Characterization of Chimeric Staphylococcus aureus Strains from Waterfowl

Area of Science:

• Microbiology
• Genomics
• Evolutionary Biology

Background:

• Staphylococcus aureus is a significant pathogen found in humans and animals, including birds.
• Characterization of S. aureus from waterfowl revealed atypical CC133 strains with unique genetic features.

Purpose of the Study:

• To investigate the genomic basis of atypical CC133 Staphylococcus aureus strains isolated from waterfowl.
• To understand the role of horizontal gene transfer in the evolution and adaptation of these avian S. aureus isolates.

Main Methods:

• DNA microarray analysis for initial strain characterization.
• Whole-genome sequencing to identify genetic inserts and rearrangements.
• Comparative genomic analysis of S. aureus lineages.

Main Results:

• Identified three distinct atypical CC133 S. aureus strains with varying large DNA inserts from CC692 and CC522 lineages.
• Detected the presence of a hemolysin-beta-integrating prophage with bird-specific virulence factors in some strains.
• Observed SCC elements lacking mecA/mecC genes, suggesting alternative resistance mechanisms.

Conclusions:

• Horizontal gene transfer, including large-scale core genomic DNA exchange, plays a crucial role in S. aureus evolution.
• Avian S. aureus isolates demonstrate significant genomic plasticity, acquiring virulence factors and adapting to new hosts.
• Novel mechanisms beyond SCC elements and phages contribute to the genetic diversification of S. aureus.