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Updated: May 28, 2025
Author Spotlight: Investigating Bacteriophage-Induced Immune Responses in Gnotobiotic Mice
Published on: January 26, 2024
Prophylactic phage administration provides a time window for delayed treatment of vancomycin-resistant Enterococcus
Wei-Xiao Wang1, Jiao-Yang Yu2, Xiu-Zhen Chen3,4
1Department of Tuberculosis, The Second Hospital of Nanjing, Affiliated to Nanjing University of Chinese Medicine, Nanjing, China.
Introduction:
Vancomycin-resistant Enterococcus faecalis (VRE) poses a significant challenge in clinical settings due to its resistance to multiple antibiotics. Phage therapy offers a promising alternative to address this resistance crisis. However, critical gaps remain regarding optimal dosing, therapeutic design, and treatment timing for phage therapy targeting VRE-induced bacteremia.
Methods:
The biological and genomic characteristics of a novel lytic phage specific to VRE were investigated. Its in vitro bactericidal and antibiofilm activities were evaluated, along with its synergy with antimicrobial agents. In vitro safety and protective efficacy were assessed using a mouse bacteremia model. The impact of phage therapy on gut microbiota was examined through 16S rDNA gene sequencing.
Results:
We isolated and characterized a novel lytic phage, vB_EfaS-1017, specific to vancomycin-resistant E. faecalis. This phage features a circular, double-stranded DNA genome (40,766 bp), sharing 91.19% identity and 79% coverage with Enterococcus phage vB_EfaS_SRH2. vB_EfaS-1017 exhibited robust bactericidal and antibiofilm activity in vitro and demonstrated synergy with levofloxacin. Safety assessments confirmed its non-toxicity to mammalian cells and lack of hemolytic activity. In a mouse bacteremia model, phage treatment alone rescued 60% of infected mice, while combining phage with levofloxacin increased survival to 80%. Prophylactic administration of phage 24 hours prior to infection failed to prevent mortality. However, a combination of prophylactic phage administration and delayed treatment rescued 60% of mice, compared to 100% mortality in the delayed treatment alone group. Additionally, phage therapy helped maintain or restore gut microbiota balance.
Discussion:
These findings underscore the potential of phage-antibiotic combinations as a superior therapeutic strategy against VRE infections. The observed synergy between phages and antibiotics highlights a promising approach to overcoming bacterial resistance and improving clinical outcomes. Furthermore, prophylactic phage administration may provide a critical time window for effective delayed treatment. Further preclinical research is essential to refine phage therapy protocols for clinical application.
Insights
A novel phage, vB_EfaS-1017, shows promise against vancomycin-resistant Enterococcus faecalis (VRE) bacteremia. Combining phage therapy with levofloxacin significantly improved survival in a mouse model, highlighting a potent strategy against VRE infections.
Area of Science:
- Microbiology
- Genomics
- Infectious Diseases
Background:
- Vancomycin-resistant Enterococcus faecalis (VRE) presents a significant clinical challenge due to multidrug resistance.
- Phage therapy is an emerging alternative for combating antibiotic-resistant bacteria.
Purpose of the Study:
- To isolate and characterize a novel lytic phage targeting VRE.
- To evaluate the efficacy and safety of phage therapy, alone and in combination with antibiotics, against VRE bacteremia.
- To assess the impact of phage therapy on the gut microbiota.
Main Methods:
- Isolation and genomic characterization of a novel lytic phage (vB_EfaS-1017).
- In vitro assessment of bactericidal and antibiofilm activities, and synergy with levofloxacin.
- In vivo evaluation of safety and efficacy in a mouse bacteremia model.
- 16S rDNA gene sequencing to analyze gut microbiota changes.
Main Results:
- The novel lytic phage vB_EfaS-1017 was identified and characterized with a double-stranded DNA genome.
- vB_EfaS-1017 demonstrated robust in vitro bactericidal and antibiofilm activity, and synergistic effects with levofloxacin.
- In vivo studies showed phage monotherapy rescued 60% of mice, while phage-levofloxacin combination increased survival to 80%.
- Phage therapy helped maintain gut microbiota balance.
Conclusions:
- Phage-antibiotic combinations represent a superior therapeutic strategy against VRE infections.
- Synergy between phages and antibiotics offers a promising approach to overcome bacterial resistance.
- Further preclinical research is necessary to optimize phage therapy protocols for clinical application.
