Work

Selective shifts in mobile antibiotic resistance genes under carbamazepine exposure in wastewater microbiomes

Year: 2026

Type: article

Abstract: Carbamazepine (CBZ) is a widely used nonantibiotic pharmaceutical that frequently persists through wastewater treatment and enters aquatic environments. CBZ has been, in simplified experimental systems, reported to stimulate horizontal gene transfer (HGT), a major process of antimicrobial resistance gene (ARG) dissemination in microbial communities. Moreover, it may facilitate selection for ARGs, directly or via co-selection. However, whether CBZ significantly modulates these processes in complex microbiomes remains insufficiently characterized. To address this gap, we exposed wastewater microbial communities to a gradient of CBZ concentrations for 3 days to evaluate early responses in community composition, ARG, and mobile genetic element (MGE) dynamics. Community structure remained largely unchanged across environmentally relevant CBZ concentrations. Most ARGs showed no consistent concentration-dependent response. However, a subset of clinically relevant ARGs increased in relative abundance in a dose-dependent manner. For the beta-lactam ARGs (blaCMY, blaOXA-48, blaCTX-M), and the trimethoprim ARG dfrA1, this increase was significantly correlated with IncP and IncW plasmid markers and the transposable element IS26, consistent with enhanced HGT-mediated dissemination. By contrast, the macrolide resistance gene ermF increased independently of the tested MGE markers, suggesting direct or host-specific selection or association with a nontested MGE. The strongest shifts occurred at sub-inhibitory CBZ concentrations within the upper range of concentrations reported in wastewater-impacted environments. These findings show that CBZ exposure can indeed influence the dissemination of selected ARGs in complex microbial communities without major effects on overall community composition, highlighting the potential for nonantibiotic pharmaceuticals to shape early resistome responses to pollutants in the environment.

Source: ISME Communications

DOI: 10.1093/ismeco/ycag140

Authors: Eda Deniz Erdem, Bing Li, Thomas U Berendonk, Uli Klümper

Institutions: Technische Universität Dresden, Tsinghua Shenzhen International Graduate School, Tsinghua University

Language: English

Topic: Pharmaceutical and Antibiotic Environmental Impacts

Subfield: Pollution

Field: Environmental Science

Domain: Physical Sciences

SDGs: Good health and well-being, Clean water and sanitation

Open Access status: gold

Estimated APC paid: $2,611