Antagonistic interaction between two key endodontic pathogens Enterococcus faecalis and Fusobacterium nucleatum

Area of Science:

• Microbiology
• Endodontics
• Bacterial Interactions

Background:

• Endodontic infections involve pathogenic bacteria like Fusobacterium nucleatum and Enterococcus faecalis.
• F. nucleatum is more prevalent in primary infections, while E. faecalis dominates secondary infections.
• Interactions between these key endodontic pathogens remain poorly understood.

Purpose of the Study:

• To investigate the interaction between F. nucleatum and E. faecalis.
• To elucidate the mechanisms driving these interactions using phenotypic and genetic methods.

Main Methods:

• Co-aggregation and competition assays were used to assess physical and physiological interactions.
• Genetic screening and biochemical measurements identified underlying mechanisms.
• Experiments were conducted under both planktonic and biofilm conditions.

Main Results:

• E. faecalis physically binds to F. nucleatum, mediated by the Fap2 adhesin of F. nucleatum.
• E. faecalis inhibits F. nucleatum growth through acid production and hydrogen peroxide (H2O2).
• E. faecalis binding and killing capabilities are essential for invading and dominating established F. nucleatum biofilms.

Conclusions:

• Multifaceted mechanisms explain the binding and antagonism between F. nucleatum and E. faecalis.
• These interactions may influence microbial composition shifts in primary versus secondary endodontic infections.