Landscape of plasmids encoding β-lactamases in disinfection residual Enterobacteriaceae from wastewater treatment plants

Zejun Lin; Zhenchao Zhou; Xinyi Shuai; Guangshu Zeng; Ruiqi Bao; Hong Chen

doi:10.1016/j.watres.2024.121549

Landscape of plasmids encoding β-lactamases in disinfection residual Enterobacteriaceae from wastewater treatment plants

Water Res. 2024 May 15:255:121549. doi: 10.1016/j.watres.2024.121549. Epub 2024 Mar 29.

Authors

Zejun Lin¹, Zhenchao Zhou¹, Xinyi Shuai¹, Guangshu Zeng¹, Ruiqi Bao¹, Hong Chen²

Affiliations

¹ College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
² College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental Resource Sciences, Zhejiang University, Hangzhou 310058, China; International Cooperation Base of Environmental Pollution and Ecological Health, Science and Technology Agency of Zhejiang, Zhejiang University, China. Electronic address: chen_hong@zju.edu.cn.

PMID: 38564891
DOI: 10.1016/j.watres.2024.121549

Abstract

Conventional disinfection processes, such as chlorination and UV radiation, are ineffective in controling antibiotic-resistant bacteria, especially disinfection residual Enterobacteriaceae (DRE) encoding β-lactamases, some of which have been classified as "critical priority pathogens" by the World Health Organization. However, few studies have focused on the transferability, phenotype, and genetic characteristics of DRE-derived plasmids encoding β-lactamases, especially extended-spectrum β-lactamases and carbapenemases. In this study, we isolated 10 typical DRE harboring plasmid-mediated bla_NDM, bla_CTX-M, or bla_TEM in post-disinfection effluent from two wastewater treatment plants (WWTPs), with transfer frequency ranging from 1.69 × 10^-6 to 3.02 × 10^-5. According to genomic maps of plasmids, all bla_NDM and bla_TEM were cascaded with IS26, and bla_CTX-M was adjacent to ISEcp1 or IS26, indicating the important role of these elements in the movement of β-lactamase-encoding genes. The presence of intact class 1 integrons on pWTPN-01 and pWTPC-03 suggested the ability of these DRE-derived plasmids to integrate other exogenous antibiotic resistance genes (ARGs). The coexistence of antibiotic, disinfectant, and heavy metal resistance genes on the same plasmid (e.g., pWTPT-03) implied the facilitating role of disinfectants and heavy metals in the transmission of DRE-derived ARGs. Notably, two plasmid transconjugants exhibited no discernible competitive fitness cost, suggesting a heightened environmental persistence. Furthermore, enhanced virulence induced by β-lactamase-encoding plasmids in their hosts was confirmed using Galleria mellonella infection models, which might be attributed to plasmid-mediated virulence genes. Overall, this study describes the landscape of β-lactamase-encoding plasmids in DRE, and highlights the urgent need for advanced control of DRE to keep environmental and ecological security.

Keywords: Antibiotic resistance; Beta-lactamases; Disinfection residual bacteria; Enterobacteriaceae; Transferable plasmids.