ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Pathogen Interactions
Volume 16 - 2025 | doi: 10.3389/fpls.2025.1664284
This article is part of the Research TopicPlant and Human Pathogen Interactions: Gaining Insights Into the Impact of Environmental and Crop Management Factors: Volume IIView all 3 articles
Multidrug Resistance in Bacteria Associated with Leafy Greens and Soil in Urban Agriculture Systems
Provisionally accepted
- University of Maryland, College Park, College Park, United States
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Urban farms and gardens support community engagement and local food production, though these agroecosystems can contain emerging environmental contaminants that contribute to the dissemination of antimicrobial resistance (AMR). Our previous research enumerated AMR bacteria associated with leafy vegetable production across leafy vegetable production environments in the greater Washington, D.C. area, identifying >100 isolates with multidrug-resistant (MDR) phenotypes. Here, we performed whole genome sequencing analysis of 87 of these strains recovered from leafy greens (n=29), root zone soil (n=42), and bulk soil (n=16) to comprehensively characterize their MDR genotypes, including taxonomy and the encoded ARGs, stress response genes, and mobile genetic elements (MGEs; e.g., plasmids, phages, conjugative elements). The MDR isolates spanned 4 phyla and 14 genera, with the majority identified as Pseudomonas (n = 29), Serratia (n = 22), Providencia (n = 11), and Bacillus (n = 11). Most of the ARG were linked to multidrug efflux, while other abundant ARG classes reflected resistance to beta-lactams and tetracyclines. While the genotypes were often conserved within respective species and even genera, the observed phenotypes within groups slightly varied, suggesting the potential roles of uncharacterized genetic elements in MDR function. Moreover, all the MDR isolates encoded at least one gene annotated as a MGE, and there were 19 distinct ARGs located within 5,000 bp upstream or downstream of these sequences, suggesting genetic linkages with potential implications for mobilization. Overall, our results indicate that the MDR bacteria in urban agriculture systems, including on fresh produce, are dominated by general soil-associated taxa (i.e., no foodborne pathogens were identified) that carry diverse ARGs and MGEs.
Keywords: Urban agriculture, whole genome sequencing, antimicrobial resistance, Environmental resistome, Plasmids
Received: 11 Jul 2025; Accepted: 25 Aug 2025.
Copyright: © 2025 Harrelson, Zeng, Gao, Toro and Blaustein. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Ryan Blaustein, University of Maryland, College Park, College Park, United States
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