Pyomelanin-producing Pseudomonas aeruginosa selected during chronic infections have a large chromosomal deletion which confers resistance to pyocins.
Fiche publication
Date publication
octobre 2016
Journal
Environmental microbiology
Auteurs
Membres identifiés du Cancéropôle Est :
Pr HOCQUET Didier
Tous les auteurs :
Hocquet D, Petitjean M, Rohmer L, Valot B, Kulasekara HD, Bedel E, Bertrand X, Plésiat P, Köhler T, Pantel A, Jacobs MA, Hoffman LR, Miller SI
Lien Pubmed
Résumé
When bacterial lineages make the transition from free-living to permanent association with hosts, they can undergo massive gene losses, for which the selective forces within host tissues are unknown. We identified here melanogenic clinical isolates of Pseudomonas aeruginosa with large chromosomal deletions (66 to 270 kbp) and characterized them to investigate how they were selected. When compared with their wild-type parents, melanogenic mutants (i) exhibited a lower fitness in growth conditions found in human tissues, such as hyperosmolarity and presence of aminoglycoside antibiotics, (ii) narrowed their metabolic spectrum with a growth disadvantage with particular carbon sources, including aromatic amino acids and acyclic terpenes, suggesting a reduction of metabolic flexibility. Despite an impaired fitness in rich media, melanogenic mutants can inhibit their wild-type parents and compete with them in coculture. Surprisingly, melanogenic mutants became highly resistant to two intraspecific toxins, the S-pyocins AP41 and S1. Our results suggest that pyocins produced within a population of infecting P. aeruginosa may have selected for bacterial mutants that underwent massive gene losses and that were adapted to the life in diverse bacterial communities in the human host. Intraspecific interactions may therefore be an important factor driving the continuing evolution of pathogens during host infections.
Mots clés
Chromosome Deletion, Chromosomes, Bacterial, genetics, Drug Resistance, Bacterial, Humans, Melanins, metabolism, Pseudomonas Infections, microbiology, Pseudomonas aeruginosa, drug effects, Pyocins, pharmacology
Référence
Environ. Microbiol.. 2016 10;18(10):3482-3493