G. mellonella larvae for PK/PD assessment of antibiotics

Before new antibiotics can be tested in human, until now pharmacological properties of the compound are tested in artificially infected rodents. The current project aims to replace mammalian models in studying the relationship between antibiotic concentration and effectiveness against pathogens in non-human organisms. Due to their biological similarities to humans, mammalian models such as rodents are at the moment still considered the gold standard for these studies. The fact, that large numbers of animals is needed to obtain the necessary data, highlights the urgent need for alternative methods. Efforts to find alternative infection models have led to the development of various invertebrate models such as the Greater Wax Moth (G. mellonella). Its innate immune system, which resembles that of mammals, allows studying infections and antibiotic effects in an environment that closely mimics human conditions. While G. mellonella has been successfully used to assess pathogen virulence and screen antimicrobial agents, its potential for studies exploring the relationship between antibiotic concentration and effectiveness has not been sufficiently evaluated. In this project, microdialysis will be used to measure the concentration of antibiotics in larvae tissues over time. Microdialysis is a minimally invasive method employing small probes with semipermeable membranes to sample fluids. This method has two major advantages: It allows directly measuring the fraction of antibiotics that is not bound to proteins and thus can act against pathogens. Furthermore, it is possible to take repeated samples within the same animal, eliminating the need for destructive sampling, where multiple animals are sacrificed at various intervals. After demonstrating the feasibility of microdialysis in healthy G. mellonella larvae concentration over time of selected antibiotics of antibiotics will be measured in infected larvae in order to evaluate the relationship of the concentration over time of an antibiotic substance and its effectiveness against the pathogen. Moreover, the impact of different dosing regimens on the efficacy against pathogens and larval survival will be evaluated. All results will be compared to those in mammalian model organisms reported in the scientific literature. Establishing microdialysis in G. mellonella as a viable technique for preclinical antibiotic testing could reduce the need for mammalian models, aligning with ethical principles in animal-based research such as the "3Rs" (replacement, reduction, refinement), while simultaneously accelerating antibiotic development, reducing costs and thus addressing the urgent need for new treatments to combat rising antibiotic resistance.