Inactivation, removal, and regrowth potential of opportunistic pathogens and antimicrobial resistance genes in recycled water systems

Barbara Drigo; Gianluca Brunetti; Samuel C Aleer; Jan M Bell; Michael D Short; Sotirios Vasileiadis; John Turnidge; Paul Monis; David Cunliffe; Erica Donner

doi:10.1016/j.watres.2021.117324

Inactivation, removal, and regrowth potential of opportunistic pathogens and antimicrobial resistance genes in recycled water systems

Water Res. 2021 Aug 1:201:117324. doi: 10.1016/j.watres.2021.117324. Epub 2021 Jun 4.

Authors

Affiliations

¹ Future Industries Institute, University of South Australia, Adelaide, SA 5001, Australia. Electronic address: barbara.drigo@unisa.edu.au.
² Future Industries Institute, University of South Australia, Adelaide, SA 5001, Australia.
³ Australian Centre for Antimicrobial Resistance Ecology, The University of Adelaide, Adelaide, SA 5005, Australia.
⁴ Laboratory of Plant and Environmental Biotechnology, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
⁵ South Australian Water Corporation, Adelaide, SA 5000, Australia; Future Industries Institute and ARC Centre of Excellence for Convergent Bio and Nano Science, University of South Australia, Adelaide, SA 5095, Australia.
⁶ Department for Health and Wellbeing, Adelaide, 5000, South Australia, Australia.

PMID: 34242935
DOI: 10.1016/j.watres.2021.117324

Abstract

With two thirds of the global population living in areas affected by water scarcity, wastewater reuse is actively being implemented or explored by many nations. There is a need to better understand the efficacy of recycled water treatment plants (RWTPs) for removal of human opportunistic pathogens and antimicrobial resistant microorganisms. Here, we used a suite of probe-based multiplex and SYBR green real-time PCR assays to monitor enteric opportunistic pathogens (EOPs; Acinetobacter baumannii, Arcobacter butzlieri, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Legionella spp., Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Enteritidis, Streptococcus spp.) and antimicrobial resistance genes (ARGs; qnrS, bla_SHV, bla_TEM, bla_GE_S, bla_KPC, bla_IMI, bla_SME, bla_NDM, bla_VIM, bla_IMP, bla_OXA-48-like, mcr-1 and mcr-3) of key concern from an antimicrobial resistance (AMR), waterborne and foodborne disease perspective. The class 1 integron-integrase gene (intl1) was quantified as a proxy for multi-drug resistance. EOPs, intl1 and ARGs absolute abundance (DNA and RNA) and metabolic activity (RNA) was assessed through three RWTPs with differing treatment trains. Our results indicate that RWTPs produced high quality recycled water for non-potable reuse by removing >95% of EOPs and ARGs, however, subpopulations of EOPs and ARGs survived disinfection and demonstrated potential to become actively growing members of the recycled water and distribution system microbiomes. The persistence of functional intl1 suggests that significant genetic recombination capacity remains in the recycled water, along with the likely presence of multi-drug resistant bacteria. Results provide new insights into the persistence and growth of EOPs, and prevalence and removal of ARGs in recycled water systems. These data will contribute towards the emerging evidence base of AMR risks in recycled water to inform quantitative risk-based policy development regarding water recycling schemes.

Keywords: Antibiotic resistance genes; Class 1 integron-integrase gene; Enteric opportunistic pathogens; Regrowth; Wastewater treatment; Water recycling.

MeSH terms

Anti-Bacterial Agents* / pharmacology
Drug Resistance, Bacterial
Drug Resistance, Multiple, Bacterial
Genes, Bacterial
Humans
Integrons
Wastewater
Water*

Substances

Anti-Bacterial Agents
Waste Water
Water