The Intraperitoneal Transcriptome of the Opportunistic Pathogen Enterococcus faecalis in Mice

Area of Science:

• Microbiology
• Molecular Biology
• Infectious Diseases

Background:

• Enterococcus faecalis is an opportunistic pathogen with significant virulence potential.
• Understanding bacterial adaptation to host environments is crucial for combating infections.

Purpose of the Study:

• To investigate the in vivo gene expression profile of Enterococcus faecalis during infection.
• To identify key adaptive mechanisms and virulence factors utilized by the bacterium within a host.

Main Methods:

• Transcriptome analysis using RNA-sequencing of E. faecalis isolated from a mouse peritonitis model.
• Identification of differentially expressed genes (induced and repressed).
• Validation of gene function through virulence assays using mutant strains.

Main Results:

• RNA-sequencing revealed 211 induced and 157 repressed genes in vivo.
• Induced genes included major virulence factors (cytolysin, gelatinase) and stress response proteins.
• Metabolic genes, particularly those for glycerol and α-/β-glucoside utilization, were significantly upregulated, suggesting adaptation to host nutrients.
• Mutants deficient in glycerol metabolism showed reduced organ colonization in a mouse model.

Conclusions:

• Enterococcus faecalis actively modifies its gene expression to survive and thrive in host conditions.
• Glycerol metabolism is a critical factor for E. faecalis virulence and colonization.
• The pentose phosphate pathway may be favored over glycolysis for increased reducing power production during infection.