Agricultural ecosystems are of special interest for monitoring the potential for antibiotic resistance to spread through the environment and contribute to human exposure. Molecular methods, which target DNA, RNA, and other molecular components of bacterial cells, present certain advantages for characterizing and quantifying markers of antibiotic resistance and their horizontal gene transfer. These include rapid, unambiguous detection of targets; consistent results; and avoidance of culture bias. However, molecular methods are also subject to limitations that are not always clearly addressed or taken into consideration in the interpretation of scientific data. In particular, DNA‐based methods do not directly assess viability or presence within an intact bacterial host, but such information may be inferred based on appropriate experimental design or in concert with complementary methods. The purpose of this review is to provide an overview of existing molecular methods for tracking antibiotic resistance in agricultural ecosystems, to define their strengths and weaknesses, and to recommend a path forward for future applications of molecular methods and standardized reporting in the literature. This will guide research along the farm‐to‐fork continuum and support comparability of the growing number of studies in the literature in a manner that informs management decisions and policy development.
Core Ideas
- Molecular tools target DNA, RNA, or proteins as markers of antibiotic resistance.
- Molecular tools test for antibiotic resistance potential, not its expression or host.
- Molecular methods and gene targets must be consistent with research questions.
- Experimental design, controls, and statistics are important in agroecosystem studies.
- Need to link molecular data from agroecosystems with human health risk end points.