Fitness effects of antimicrobial resistance genes in changing environments

Fitness effects of antimicrobial resistance genes in changing environments | Research Square Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Help Center Sign In Submit a Preprint Cite Share Download PDF Article Fitness effects of antimicrobial resistance genes in changing environments Jose Antonio Escudero, Alberto Hipólito, Lucía García-Pastor, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8872954/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The evolutionary success of antimicrobial resistance (AMR) genes is generally seen as a trade-off between their function in the presence and their cost in the absence of antibiotics. Mobile integrons are genetic elements that recruit and disseminate dozens of AMR genes among Gram-negative pathogens. Here, we have measured the fitness effects of 136 integron genes conferring resistance against several antibiotic families. We have found a significant proportion having neutral and positive effects in the absence of antibiotics. We confirmed this using a mouse model, where we also observed cases of changes in the sign of fitness effects. This led us to unveil that oxygen availability modulates the cost of AMR genes. Using a stochastic model, we show that fluctuating aerobic/anaerobic conditions can rescue AMR genes in the absence of selective pressure. Here we provide a comprehensive analysis of the cost of AMR at the gene level challenging the traditional fitness-resistance trade-off hypothesis. Biological sciences/Microbiology/Antimicrobials/Antimicrobial resistance Biological sciences/Microbiology/Microbial genetics/Bacterial genes Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryMaterial.pdf Supplementary Figures and Materials Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information

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