Project Objectives

• Establish zebrafish embryo infection models using Pseudomonas aeruginosa and Enterococcus faecali.
• Develop assays to quantify bacterial load in vivo.
• Design and optimize a high-throughput screening platform for phage and endolysin candidates.
• Identify the top 5 candidates for each infection type from phage and protein libraries.
• Validate the two best candidates in an independent laboratory.
• Disseminate findings and establish a service platform at ZHAW for academic and industry users.

3Rs Impact

• Replaces large numbers of mice typically required for early antimicrobial screening by using zebrafish embryos.
• Improves scientific quality through real-time imaging, enabling mechanistic insight unattainable in mouse models.
• Accelerates candidate selection, which will minimise downstream animal testing.
• Promotes adoption of 3Rs-aligned methods via a service platform and dissemination activities.

Background

Antibiotic resistance is a significant global health threat. A growing number of bacteria, such as multidrug-resistant Pseudomonas aeruginosa and vancomycin-resistant Enterococcus faecalis increasingly evade available treatments, making the development of new antimicrobial strategies critically important. Bacteriophages, and their derived proteins, such as endolysin, represent a promising class of alternatives thanks to their ability to kill bacteria with high specificity and limited side effects. However, identifying effective phage-based therapeutics typically requires large numbers of rodent infection experiments.

To address this, the project will use zebrafish embryos, an established, ethically favourable infection model, to screen antimicrobial activity before any rodent studies are considered. Zebrafish embryos are genetically and physiologically suited for modelling infection, enabling real-time tracking of bacterial behaviour and treatment responses using fluorescence or multiphoton microscopy. By establishing and validating a robust zebrafish embryo screening pipeline, the project will identify the most effective phage candidates early, thereby greatly reducing the number of rodents needed in downstream preclinical testing and accelerating the development of novel antimicrobials.