Host- and tissue-specific pathogenic traits of Staphylococcus aureus

Area of Science:

• Veterinary Microbiology
• Genomics
• Infectious Diseases

Background:

• Staphylococcus aureus is a significant pathogen in both humans and animals.
• Understanding the genetic relatedness of S. aureus strains from different hosts is crucial for infection control and One Health initiatives.

Purpose of the Study:

• To compare the genetic profiles of Staphylococcus aureus strains from infected animals and humans.
• To identify specific genetic markers associated with host origin and disease type.

Main Methods:

• Comparative genomics using high-throughput amplified fragment length polymorphism (AFLP) analysis.
• Genotyping of 77 veterinary S. aureus isolates and comparison with a database of 1,056 human isolates.
• Analysis of the distribution of 10 key virulence genes across different strain clusters.

Main Results:

• S. aureus strains from pets clustered with common human strains (cluster I).
• Mastitis-associated S. aureus strains from animals formed a distinct cluster (IVa), grouping with human bacteremia strains.
• The toxic shock syndrome toxin (tst) gene was significantly more prevalent in veterinary and mastitis strains.
• The collagen binding protein (cna) gene was less common in invasive human strains.
• Overall virulence gene load did not significantly differ between human and animal strains.

Conclusions:

• Invasive Staphylococcus aureus infections in pets and humans often originate from genetically similar strains.
• Mastitis-associated S. aureus in farm animals represents a distinct genetic lineage with a higher prevalence of the tst gene.
• These findings highlight the importance of considering animal-to-human pathogen transmission and specific animal-associated S. aureus reservoirs.