Mobilization of Antibiotic Resistance: Are Current Approaches for Colocalizing Resistomes and Mobilomes Useful?

Ilya Slizovskiy, Kingshuk Mukherjee, Christopher J Dean, Christina Boucher, Noelle R. Noyes

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24 Scopus citations


Antimicrobial resistance (AMR) poses a global human and animal health threat, and predicting AMR persistence and transmission remains an intractable challenge. Shotgun metagenomic sequencing can help overcome this by enabling characterization of AMR genes within all bacterial taxa, most of which are uncultivatable in laboratory settings. Shotgun sequencing, therefore, provides a more comprehensive glance at AMR “potential” within samples, i.e., the “resistome.” However, the risk inherent within a given resistome is predicated on the genomic context of various AMR genes, including their presence within mobile genetic elements (MGEs). Therefore, resistome risk stratification can be advanced if AMR profiles are considered in light of the flanking mobilizable genomic milieu (e.g., plasmids, integrative conjugative elements (ICEs), phages, and other MGEs). Because such mediators of horizontal gene transfer (HGT) are involved in uptake by pathogens, investigators are increasingly interested in characterizing that resistome fraction in genomic proximity to HGT mediators, i.e., the “mobilome”; we term this “colocalization.” We explored the utility of common colocalization approaches using alignment- and assembly-based techniques, on clinical (human) and agricultural (cattle) fecal metagenomes, obtained from antimicrobial use trials. Ordination revealed that tulathromycin-treated cattle experienced a shift in ICE and plasmid composition versus untreated animals, though the resistome was unaffected during the monitoring period. Contrarily, the human resistome and mobilome composition both shifted shortly after antimicrobial administration, though this rebounded to pre-treatment status. Bayesian networks revealed statistical AMR-MGE co-occurrence in 19 and 2% of edges from the cattle and human networks, respectively, suggesting a putatively greater mobility potential of AMR in cattle feces. Conversely, using Mobility Index (MI) and overlap analysis, abundance of de novo-assembled contigs supporting resistomes flanked by MGE increased shortly post-exposure within human metagenomes, though > 40 days after peak dose such contigs were rare (∼2%). MI was not substantially altered by antimicrobial exposure across all cattle metagenomes, ranging 0.5–4.0%. We highlight that current alignment- and assembly-based methods estimating resistome mobility yield contradictory and incomplete results, likely constrained by approach-specific data inputs, and bioinformatic limitations. We discuss recent laboratory and computational advancements that may enhance resistome risk analysis in clinical, regulatory, and commercial applications.

Original languageEnglish (US)
Article number1376
JournalFrontiers in Microbiology
StatePublished - Jun 30 2020

Bibliographical note

Funding Information:
We would like to thank Dr. Enrique Doster for his technical assistance in the execution of the AMRPlusPlus pipeline. We are also grateful to Lidiya V. Zyskina for her technical assistance with graphical design and organization of visual data in this manuscript. Funding. Financial support for this study was provided by the National Institute of Allergy and Infectious Diseases (NIAID) of the U.S. National Institutes of Health (NIH), Project No. 1R01AI141810-01. Funders had no role in study design, data collection and interpretation, or decision to submit the work for publication.

Publisher Copyright:
© Copyright © 2020 Slizovskiy, Mukherjee, Dean, Boucher and Noyes.


  • antimicrobial resistance
  • assembly
  • colocalization
  • mobile genetic elements
  • network analysis


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