Characterization of genetic diversity and population structure within Staphylococcus chromogenes by multilocus...

Area of Science:

• Microbiology
• Genetics
• Veterinary Science

Background:

• Staphylococcus chromogenes is a common cattle skin commensal.
• It is a frequent cause of bovine mastitis and intramammary infections.

Purpose of the Study:

• To develop and validate a seven-locus Multilocus Sequence Typing (MLST) scheme for S. chromogenes.
• To assess the genetic diversity and population structure of S. chromogenes isolates from different geographic locations.

Main Methods:

• Developed a seven-locus MLST scheme for S. chromogenes.
• Tested the scheme on 120 isolates from Vermont, Washington State (USA), and Belgium.
• Performed phylogenetic analysis to determine genetic relationships and diversification patterns.

Main Results:

• Identified 46 unique sequence types (STs), with most being location-specific.
• Achieved high discrimination power (95.6% overall).
• Phylogenetic analysis revealed a core genetic lineage (39 STs) primarily shaped by mutation, with evidence of recent clonal expansion in two clusters. Seven outlier STs showed greater diversification due to recombination and hypervariable alleles.

Conclusions:

• The developed MLST scheme is a robust tool for typing S. chromogenes.
• The study highlights significant genetic diversity and population structure within S. chromogenes, with evidence of clonal expansion and potential ancestral genotypes.