LysK1-Sub5 fusion endolysin reduces Klebsiella pneumoniae MIC by up to 6.1-fold and accelerates wound healing in mice.
Background
Multidrug-resistant (MDR) Klebsiella pneumoniae (K. pneumoniae) is a critical opportunistic pathogen, driving the urgent need for alternative therapeutics. Phage-derived endolysins are promising antimicrobials, but their efficacy against Gram-negative bacteria is severely limited by the outer membrane (OM), which prevents access to the target peptidoglycan layer. Overcoming this OM barrier is crucial for endolysin-based therapies to reach their full potential against these challenging infections.
Study Design
Researchers engineered a novel antimicrobial agent by fusing the antimicrobial peptide (AMP) Sub5 with LysK1, a phage-derived endolysin specific for K. pneumoniae. The study evaluated the fused protein, LysK1-Sub5, against unfused LysK1 in vitro by measuring minimum inhibitory concentration (MIC) against various K. pneumoniae strains. In vivo efficacy was assessed using a mouse skin wound infection model, where the ability of LysK1-Sub5 to accelerate wound healing and reduce bacterial load was observed over time.
Results
The engineered LysK1-Sub5 fusion protein demonstrated significantly enhanced antibacterial activity compared to LysK1 alone. In vitro, LysK1-Sub5 reduced the MIC against K. pneumoniae by 2.7 to 6.1-fold, effectively inhibiting bacterial growth within 16 h without requiring an external OM permeabilizer. This fusion also exhibited stable environmental tolerance and broad-spectrum lytic activity. In a mouse skin wound infection model, LysK1-Sub5 accelerated wound healing and effectively reduced K. pneumoniae infection, indicating its potential as a topical antimicrobial agent.
LysK1-Sub5 reduced the minimum inhibitory concentration (MIC) against K. pneumoniae by 2.7 to 6.1-fold compared to unfused LysK1.
Key Findings
- LysK1-Sub5 reduced K. pneumoniae MIC by 2.7 to 6.1-fold compared to LysK1.
- LysK1-Sub5 inhibited K. pneumoniae growth within 16 hours without an OM permeabilizer.
- The fusion protein demonstrated stable environmental tolerance and broad-spectrum lytic activity.
- LysK1-Sub5 accelerated wound healing in a mouse skin wound infection model.
- LysK1-Sub5 effectively reduced K. pneumoniae infection in vivo.
Why It Matters
This study presents a promising strategy to overcome the outer membrane barrier, a major hurdle for endolysin-based therapies against Gram-negative bacteria like K. pneumoniae. LysK1-Sub5 offers a novel approach for treating MDR K. pneumoniae infections, particularly as a topical antimicrobial agent for skin wounds. The fusion engineering concept could be broadly applicable to enhance other endolysins, potentially expanding their utility against a wider range of resistant pathogens. This work moves closer to developing effective alternatives to conventional antibiotics, addressing a critical unmet medical need.
klebsiella-pneumoniae
mdr
endolysin
antimicrobial-peptide
fusion-protein
wound-healing