(P23-026-25) Antimicrobial Resistance in Gastrointestinal Bacterial Communities of First-Time Gardeners

Objectives: Gardening is known to improve physical and psychological health, and intake of vegetables. However, given the role of animal-based soil amendments in gardening, the impact of gardening on the antimicrobial resistance gene (ARG) reservoir in the gut microbiota is unknown. Thus, the objective of this work was to assess the resistome (the antimicrobial resistance and mobile genetic element (MGE) gene abundance) in human stool samples collected from first-time gardeners.

Methods: All samples were collected during the 2019 gardening season near Lansing, MI. Eleven participants were provided compost containing cow manure mixed with plant-based materials (DMP) to use in their plots. Participants provided stool samples for analysis pre-gardening (T1), after compost addition (T2), and at harvest time (T3). DNA was extracted and stored at –20 C until use. Quantitative real-time PCR was used to determine the ARG and MGE in each sample. Resulting data was analyzed using packages vegan, ggplot2, ggbreak, patchwork, and tidyr in R software.

Results: The alpha diversity of ARG in stool samples was similar across timepoints. The alpha diversity was compared by antibiotic class, with statistical testing performed between timepoints. Richness scores were similar between classes and timepoints, however, richness of ARG targeting fluoroquinolones increased over the garden season (p = 0.04). Shannon and Inverse Simpson scores were similar for all classes and timepoints. The composition (Sorensen) and structure (Bray-Curtis) of the MGE and AMR genes in stool samples collected from first-time gardeners who had amended their soil with DMP was similar between timepoints (p >= 0.05). For 7 of 11 participants, ARG beta-diversity was numerically greater (further from 0) before gardening.

Conclusions: In this pilot study, AMR was similar across the gardening season in the gut microbiomes of first-time gardeners. Thus, at least with dairy cow-sourced soil amendments, gardening did not increase the antibiotic resistance reservoir in the human gut microbiota.

Funding Sources: This work was supported by the Education and Workforce Development Program, grant no. MICL08568/project accession no. 1019162, from the U.S. Department of Agriculture, National Institute of Food and Agriculture, and Wayne State University faculty research funds.