Abstract

Pseudomonas aeruginosa is the archetypal opportunistic pathogen adapting to diverse environments in part because of its genome variability due to acquisition of genomic islands trough horizontal gene transfer. We propose to use Caenorhabditis elegans and genomic island deletion mutants created through homologous recombination to investigate the contribution to virulence of genomic islands in clinical isolates. A C . elegans-based highthroughput assay (HTA) was established, validated against a previously described slow-killing assay (SKA) and employed to screen a panel of P. aeruginosa mutants created by deletion of tRNA gene-associated genomic islands. Out of 19 mutant–wild-type pairs tested, four mutants showed higher HTA scores than partner wild-type strains, indicative of reduced virulence relative to the comparator strain; three of these island-minus mutants were also 20 to 50% attenuated in comparison with wild-type when tested in SKA .