Synergy Between Two Chimeric Lysins to Kill Streptococcus pneumoniae

Area of Science:

• Microbiology
• Biochemistry
• Antimicrobial Research

Background:

• Antibiotic resistance is a growing global health threat, necessitating novel therapeutic approaches.
• Phage lysins are emerging as potent antimicrobial agents with unique mechanisms of action.
• Streptococcus pneumoniae causes significant human infectious diseases, and multiresistant strains pose a particular challenge.

Purpose of the Study:

• To investigate the synergistic antibacterial activity of two chimeric lysins, Cpl-711 and PL3, against Streptococcus pneumoniae.
• To evaluate the efficacy of the combined lysins in inhibiting bacterial growth and eradicating planktonic and biofilm-formed cells.
• To assess the therapeutic potential of synergistic lysin combinations in a relevant animal model of infection.

Main Methods:

• Enzymatic degradation assays using purified pneumococcal cell walls.
• In vitro checkerboard assays to determine synergistic inhibitory concentrations.
• Assessment of bactericidal activity against planktonic and biofilm-grown Streptococcus pneumoniae.
• In vivo efficacy evaluation in an adult zebrafish model of pneumococcal infection.

Main Results:

• Cpl-711 and PL3 lysins demonstrated synergistic cooperation in degrading pneumococcal cell walls.
• The combination significantly reduced the required enzyme concentration for growth inhibition (sum of fractional inhibitory concentrations ≤0.5).
• Synergistic treatment resulted in a substantial increase in bactericidal effect (≥2 logs) compared to individual lysins.
• Combined lysins showed significant efficacy in reducing bacterial load in a zebrafish infection model.

Conclusions:

• The catalytically diverse chimeric lysins Cpl-711 and PL3 exhibit potent synergistic activity against Streptococcus pneumoniae.
• This synergistic combination offers a promising strategy for developing highly efficient antibacterial enzymes to combat multiresistant bacterial infections.
• The findings support the potential of formulating enzyme-based therapies as alternatives or complements to conventional antibiotics.