EPS inhibitor treatment of Salmonella impacts evolution without selecting for resistance to biofilm inhibition

Abstract Virulence factors of pathogens, such as toxin production and biofilm formation, often exhibit a public character, providing benefits to nearby non-producers. Consequently, anti-virulence drugs targeting these public traits may not select for resistance, as resistant mutants that resume prod...

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Main Authors: Mathieu Joos, Sybren Van Ginneken, Xabier Villanueva, Marie Dijkmans, Guglielmo A. Coppola, Camilo Andres Pérez-Romero, Thijs Vackier, Erik Van der Eycken, Kathleen Marchal, Bram Lories, Hans P. Steenackers
Format: Article
Language:English
Published: Nature Portfolio 2025-05-01
Series:npj Biofilms and Microbiomes
Online Access:https://doi.org/10.1038/s41522-025-00693-y
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author Mathieu Joos
Sybren Van Ginneken
Xabier Villanueva
Marie Dijkmans
Guglielmo A. Coppola
Camilo Andres Pérez-Romero
Thijs Vackier
Erik Van der Eycken
Kathleen Marchal
Bram Lories
Hans P. Steenackers
author_facet Mathieu Joos
Sybren Van Ginneken
Xabier Villanueva
Marie Dijkmans
Guglielmo A. Coppola
Camilo Andres Pérez-Romero
Thijs Vackier
Erik Van der Eycken
Kathleen Marchal
Bram Lories
Hans P. Steenackers
author_sort Mathieu Joos
collection DOAJ
description Abstract Virulence factors of pathogens, such as toxin production and biofilm formation, often exhibit a public character, providing benefits to nearby non-producers. Consequently, anti-virulence drugs targeting these public traits may not select for resistance, as resistant mutants that resume production of the virulence factor share the benefits of their resistance with surrounding sensitive cells. In agreement with this, we show that even after long-term treatment with a 2-amino-imidazole (2-AI) biofilm inhibitor, Salmonella populations remained as susceptible to biofilm inhibition as the ancestral populations. Nonetheless, further genotypic and phenotypic analysis revealed that the Salmonella populations did adapt to the treatment and accumulated mutations in efflux pump regulators and alternative sigma factors. These mutations resulted in a reduced biofilm-forming capacity and increased efflux activity. Their selection was due to a growth delaying side effect of the biofilm inhibitor. Enhanced efflux activity helped overcome this growth delay, providing a fitness advantage over the ancestor. Finally, we demonstrate that chemical modification of the inhibitor enhances its specificity by partially alleviating the unintended growth delay while retaining the anti-biofilm activity, which in turn eliminated the selection pressure for increased efflux. Overall, our findings highlight that while unintended side effects can complicate anti-virulence strategies, adaptation to these effects does not necessarily restore the inhibited virulence trait. Moreover, chemical modification can mitigate these unintended side effects and enhance drug specificity.
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spelling doaj-art-dd3cd89477f646ffb3e7a904341a27492025-08-20T02:15:00ZengNature Portfolionpj Biofilms and Microbiomes2055-50082025-05-0111111510.1038/s41522-025-00693-yEPS inhibitor treatment of Salmonella impacts evolution without selecting for resistance to biofilm inhibitionMathieu Joos0Sybren Van Ginneken1Xabier Villanueva2Marie Dijkmans3Guglielmo A. Coppola4Camilo Andres Pérez-Romero5Thijs Vackier6Erik Van der Eycken7Kathleen Marchal8Bram Lories9Hans P. Steenackers10KU Leuven - MiCA Lab, Centre of Microbial and Plant GeneticsKU Leuven - MiCA Lab, Centre of Microbial and Plant GeneticsKU Leuven - MiCA Lab, Centre of Microbial and Plant GeneticsKU Leuven - MiCA Lab, Centre of Microbial and Plant GeneticsKU Leuven - MiCA Lab, Centre of Microbial and Plant GeneticsDepartment of Plant Biotechnology and Bioinformatics, UGent – Internet Technology and Data Science Lab (IDLab)KU Leuven - MiCA Lab, Centre of Microbial and Plant GeneticsDepartment of Chemistry, KU Leuven - Laboratory for Organic & Microwave-Assisted Chemistry (LOMAC)Department of Plant Biotechnology and Bioinformatics, UGent – Internet Technology and Data Science Lab (IDLab)KU Leuven - MiCA Lab, Centre of Microbial and Plant GeneticsKU Leuven - MiCA Lab, Centre of Microbial and Plant GeneticsAbstract Virulence factors of pathogens, such as toxin production and biofilm formation, often exhibit a public character, providing benefits to nearby non-producers. Consequently, anti-virulence drugs targeting these public traits may not select for resistance, as resistant mutants that resume production of the virulence factor share the benefits of their resistance with surrounding sensitive cells. In agreement with this, we show that even after long-term treatment with a 2-amino-imidazole (2-AI) biofilm inhibitor, Salmonella populations remained as susceptible to biofilm inhibition as the ancestral populations. Nonetheless, further genotypic and phenotypic analysis revealed that the Salmonella populations did adapt to the treatment and accumulated mutations in efflux pump regulators and alternative sigma factors. These mutations resulted in a reduced biofilm-forming capacity and increased efflux activity. Their selection was due to a growth delaying side effect of the biofilm inhibitor. Enhanced efflux activity helped overcome this growth delay, providing a fitness advantage over the ancestor. Finally, we demonstrate that chemical modification of the inhibitor enhances its specificity by partially alleviating the unintended growth delay while retaining the anti-biofilm activity, which in turn eliminated the selection pressure for increased efflux. Overall, our findings highlight that while unintended side effects can complicate anti-virulence strategies, adaptation to these effects does not necessarily restore the inhibited virulence trait. Moreover, chemical modification can mitigate these unintended side effects and enhance drug specificity.https://doi.org/10.1038/s41522-025-00693-y
spellingShingle Mathieu Joos
Sybren Van Ginneken
Xabier Villanueva
Marie Dijkmans
Guglielmo A. Coppola
Camilo Andres Pérez-Romero
Thijs Vackier
Erik Van der Eycken
Kathleen Marchal
Bram Lories
Hans P. Steenackers
EPS inhibitor treatment of Salmonella impacts evolution without selecting for resistance to biofilm inhibition
npj Biofilms and Microbiomes
title EPS inhibitor treatment of Salmonella impacts evolution without selecting for resistance to biofilm inhibition
title_full EPS inhibitor treatment of Salmonella impacts evolution without selecting for resistance to biofilm inhibition
title_fullStr EPS inhibitor treatment of Salmonella impacts evolution without selecting for resistance to biofilm inhibition
title_full_unstemmed EPS inhibitor treatment of Salmonella impacts evolution without selecting for resistance to biofilm inhibition
title_short EPS inhibitor treatment of Salmonella impacts evolution without selecting for resistance to biofilm inhibition
title_sort eps inhibitor treatment of salmonella impacts evolution without selecting for resistance to biofilm inhibition
url https://doi.org/10.1038/s41522-025-00693-y
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