Modeling of the infectious process in Galleria mellonella larvae to evaluate the antibacterial effect of cationic peptide compounds in vivo

A comparative virulence assessment of Escherichia coli ATCC 25922, E. coli M-17, Pseudomonas fluorescens ATCC 948, Bacillus subtilis ATCC 6633, Listeria innocua M-2, and Listeria welshimeri Bel-19 strains was conducted using the Galleria mellonella (greater wax moth) infection model. All tested strains were capable of causing infection, altering the general condition of the larvae (melanization, decreased motility, and cocoon formation). Furthermore, the study demonstrated that larval survival decreased with increasing infectious dose of bacteria and depended on larval weight. A comparative analysis of the antibacterial activity of cationic peptide compounds (colistin and protamine) in a model organism revealed that colistin ensures 100% survival of larvae infected with E. coli ATCC 25922. Protamine increased the survival of wax moth larvae after infection with B. subtilis ATCC 6633 and L. innocua M-2 compared to the control. Thus, G. mellonella larvae can be used as a model for inducing infection and subsequently in vivo assessing bacterial sensitivity to cationic peptides.