Differential response to prolonged amoxicillin treatment: long-term resilience of the microbiome versus long-lasting perturbations in the gut resistome

Achal Dhariwal; Lars Christian Haugli Bråten; Kjersti Sturød; Gabriela Salvadori; Ahmed Bargheet; Heidi Åmdal; Roger Junges; Dag Berild; John-Anker Zwart; Kjersti Storheim; Fernanda Cristina Petersen

doi:10.1080/19490976.2022.2157200

Differential response to prolonged amoxicillin treatment: long-term resilience of the microbiome versus long-lasting perturbations in the gut resistome

Gut Microbes. 2023 Jan-Dec;15(1):2157200. doi: 10.1080/19490976.2022.2157200.

Authors

Affiliations

¹ Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
² Department of Research and Innovation, Division of Clinical Neuroscience, Oslo University Hospital HF, Oslo, Norway.
³ Department of Infectious Diseases, Oslo University Hospital HF, Oslo, Norway.
⁴ Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
⁵ Department of Physiotherapy, Faculty of Health Science, Oslo Metropolitan University, Oslo, Norway.

Abstract

The collateral impact of antibiotics on the microbiome has attained increasing attention. However, the ecological consequences of long-term antibiotic exposure on the gut microbiome, including antibiotic resistance, are still limited. Here, we investigated long-term exposure effects to amoxicillin on the human gut microbiome and resistome. Fecal samples were collected from 20 patients receiving 3-months of amoxicillin or placebo treatment as part of a Norwegian multicenter clinical trial on chronic low back pain (AIM study). Samples were collected at baseline, last day of treatment, and 9 months after antibiotic cessation. The abundance and diversity of microbial and resistome composition were characterized using whole shotgun and functional metagenomic sequencing data. While the microbiome profiles of placebo subjects were stable over time, discernible changes in diversity and overall microbiome composition were observed after amoxicillin treatment. In particular, health-associated short-chain fatty acid producing species significantly decreased in proportion. However, these changes were short-lived as the microbiome showed overall recovery 9 months post-treatment. On the other hand, exposure to long-term amoxicillin was associated with an increase in total antimicrobial resistance gene load and diversity of antimicrobial resistance genes, with persistent changes even at 9 months post-treatment. Additionally, beta-lactam resistance was the most affected antibiotic class, suggesting a targeted response to amoxicillin, although changes at the gene level varied across individuals. Overall, our results suggest that the impact of prolonged amoxicillin exposure was more explicit and long-lasting in the fecal resistome than in microbiome composition. Such information is relevant for designing rational administration guidelines for antibiotic therapies.

Keywords: Antimicrobial resistance; Modic changes; amoxicillin; antibiotics; antimicrobial resistance gene; chronic low back pain; functional metagenomics; microbiome; resistome; shotgun.

Publication types

Multicenter Study
Research Support, Non-U.S. Gov't

MeSH terms

Amoxicillin / pharmacology
Amoxicillin / therapeutic use
Anti-Bacterial Agents / pharmacology
Anti-Bacterial Agents / therapeutic use
Feces
Gastrointestinal Microbiome*
Humans
Microbiota*

Substances

Amoxicillin
Anti-Bacterial Agents

Grants and funding

This work was supported by the Norwegian Research Council (NFR) (project number: 273833, 274867), Olav Thon Foundation (project number: 421258), by governmental organizations Helse Sør-Øst RHF (grant number: 2015090) and KLINBEFORSK (grant number: 2017201).