Effect of antibiotic spectrum on the abundance of resistant bacteria in multispecies communities

Magnus Aspenberg; Erik Andreas Martens; Kristofer Wollein Waldetoft

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arXiv · 2604.18345

Effect of antibiotic spectrum on the abundance of resistant bacteria in multispecies communities

Magnus Aspenberg·Erik Andreas Martens·Kristofer Wollein Waldetoft

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Abstract

Antibiotic resistance is a major threat to global health. It emerges in multispecies microbial communities under antibiotic exposure. This makes antibiotic spectrum -- a drug's distribution of effects across species -- a potential key parameter in resistance management. However, we currently lack evolutionary theory for resistance dynamics in a multispecies setting. Analysing established community ecology theory, we develop a simple mathematical measure for how one taxon (strain or species) affects another taxon through all direct and indirect interactions in a complex interaction network. Using this, we derive the expected effects of different antibiotic spectra on the abundance of resistant taxa in microbial communities. This furthers our understanding of microbial evolutionary ecology in multispecies communities, and provides a formal theoretical basis for empirical work on optimal antibiotic choice.

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Magnus Aspenberg, Erik Andreas Martens, Kristofer Wollein Waldetoft. 2026-04-20. Effect of antibiotic spectrum on the abundance of resistant bacteria in multispecies communities. https://arxiv.org/abs/2604.18345

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