cad a22 4500 555301214 20190312033533.0 cr unu---uuuuu 190206e20180910xx s 000 0 eng 10.5167/uzh-161757 doi 10.1093/emph/eoy026 doi (ZORA)oai:www.zora.uzh.ch:161757 580 ddc Probing the evolutionary robustness of two repurposed drugs targeting iron uptake in Pseudomonas aeruginosa [Elektronische Daten] [Chiara Rezzoagli, David Wilson, Michael Weigert, Stefan Wyder, Rolf Kümmerli] openAccess eu-repo Background and objectives: Treatments that inhibit the expression or functioning of bacterial virulence factors hold great promise to be both effective and exert weaker selection for resistance than conventional antibiotics. However, the evolutionary robustness argument, based on the idea that antivirulence treatments disarm rather than kill pathogens, is controversial. Here, we probe the evolutionary robustness of two repurposed drugs, gallium and flucytosine, targeting the iron-scavenging pyoverdine of the opportunistic human pathogen Pseudomonas aeruginosa. Methodology: We subjected replicated cultures of bacteria to two concentrations of each drug for 20 consecutive days in human serum as an ex vivo infection model. We screened evolved populations and clones for resistance phenotypes, including the restoration of growth and pyoverdine production, and the evolution of iron uptake by-passing mechanisms. We whole-genome sequenced evolved clones to identify the genetic basis of resistance. Results: We found that mutants resistant against antivirulence treatments readily arose, but their selective spreading varied between treatments. Flucytosine resistance quickly spread in all populations due to disruptive mutations in upp, a gene encoding an enzyme required for flucytosine activation. Conversely, resistance against gallium arose only sporadically, and was based on mutations in transcriptional regulators, upregulating pyocyanin production, a redox-active molecule promoting siderophore-independent iron acquisition. The spread of gallium resistance was presumably hampered because pyocyanin-mediated iron delivery benefits resistant and susceptible cells alike. Conclusions and implications: Our work highlights that antivirulence treatments are not evolutionarily robust per se. Instead, evolutionary robustness is a relative measure, with specific treatments occupying different positions on a continuous scale. Department of Plant and Microbial Biology zora Evolution in Action: From Genomes to Ecosystems zora Microbiology, Evolution zora Rezzoagli Chiara joint author Wilson David joint author Weigert Michael joint author Wyder Stefan joint author Kümmerli Rolf joint author Evolution, Medicine, and Public Health 6:246-259 https://www.zora.uzh.ch/id/eprint/161757/1/Rezzoagli_EMPH_2018.pdf text/html WWW-Backlink auf das Repository 1 Journal Article PeerReviewed zora ZORA 856 40 https://www.zora.uzh.ch/id/eprint/161757/1/Rezzoagli_EMPH_2018.pdf text/html WWW-Backlink auf das Repository ZORA 700 1- Rezzoagli Chiara joint author ZORA 700 1- Wilson David joint author ZORA 700 1- Weigert Michael joint author ZORA 700 1- Wyder Stefan joint author ZORA 700 1- Kümmerli Rolf joint author ZORA 773 0- Evolution, Medicine, and Public Health 6:246-259 BK010053 XK010053 XK010000 ZORA ZORA ZORA Journal Article openAccess