Wastewater Treatment Works: A Last Line of Defense for Preventing Antibiotic Resistance Entry Into the Environment

Keira Tucker; Wendy Stone; Marelize Botes; Edward J. Feil; Gideon M. Wolfaardt

doi:10.3389/frwa.2022.883282

Wastewater Treatment Works: A Last Line of Defense for Preventing Antibiotic Resistance Entry Into the Environment

Keira Tucker, Wendy Stone, Marelize Botes, Edward J. Feil, Gideon M. Wolfaardt

Research output: Contribution to journal › Article › peer-review

5 Citations (SciVal)

Abstract

With their large, diverse microbial communities chronically exposed to sub-inhibitory antibiotic concentrations, wastewater treatment works (WWTW) have been deemed hotspots for the emergence and dissemination of antimicrobial resistance, with growing concern about the transmission of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) into receiving surface waters. This study explored (1) the prevalence of ARG and ARB in local WWTW, (2) the effect of sub-inhibitory antimicrobial exposure on ARG copy numbers in pure cultures from WWTW, and (3) two WWTW with different treatment configurations. For each WWTW, qPCR determined the prevalence of mcr3, sul1, sul2, and bla_KPC during the treatment process, and culture methods were used to enumerate and identify ARB. Bacterial colonies isolated from effluent samples were identified by 16S rDNA sequencing and their respective minimum inhibitory concentrations (MIC) were determined. These were compared to the MICs of whole community samples from the influent, return activated sludge, and effluent of each WWTW. Resistance genes were quantified in 11 isolated cultures before and after exposure to sub-MIC concentrations of target antibiotics. The numbers of ARG and ARB in both WWTW effluents were notably reduced compared to the influent. Sul1 and sul2 gene copies increased in cultures enriched in sub-MIC concentrations of sulfamethoxazole, while bla_KPC decreased after exposure to amoxicillin. It was concluded, within the parameters of this study, that WWTW assist in reducing ARG and ARB, but that sub-inhibitory exposure to antimicrobials has a varied effect on ARG copy number in pure cultures.

Original language	English
Article number	883282
Journal	Frontiers in Water
Volume	4
DOIs	https://doi.org/10.3389/frwa.2022.883282
Publication status	Published - 16 May 2022

Bibliographical note

Funding Information:
KT was supported in part by the National Research Foundation of South Africa (Grant numbers: 118159 and 130527) and the Water Research Commission (Project No. K5/2733). WS was supported by Biogeochemistry Research Infrastructure Platform (BIOGRIP), funded by the Department of Science and Innovation of South Africa.

Funding Information:
The authors wish to thank Edward Archer, Mercia Volschenk, and the City of Cape Town for assisting with and permitting sampling of WWTW, the Central Analytical Facility at Stellenbosch University for DNA sequencing support, and the financial assistance from the NRF, WRC, and BIOGRIP.

Keywords

antibiotic resistance genes
colistin
sub-inhibitory antibiotic concentrations
sulfamethoxazole
wastewater effluent
β-lactamases

ASJC Scopus subject areas

Water Science and Technology

Access to Document

10.3389/frwa.2022.883282Licence: CC BY

Cite this

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title = "Wastewater Treatment Works: A Last Line of Defense for Preventing Antibiotic Resistance Entry Into the Environment",

abstract = "With their large, diverse microbial communities chronically exposed to sub-inhibitory antibiotic concentrations, wastewater treatment works (WWTW) have been deemed hotspots for the emergence and dissemination of antimicrobial resistance, with growing concern about the transmission of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) into receiving surface waters. This study explored (1) the prevalence of ARG and ARB in local WWTW, (2) the effect of sub-inhibitory antimicrobial exposure on ARG copy numbers in pure cultures from WWTW, and (3) two WWTW with different treatment configurations. For each WWTW, qPCR determined the prevalence of mcr3, sul1, sul2, and blaKPC during the treatment process, and culture methods were used to enumerate and identify ARB. Bacterial colonies isolated from effluent samples were identified by 16S rDNA sequencing and their respective minimum inhibitory concentrations (MIC) were determined. These were compared to the MICs of whole community samples from the influent, return activated sludge, and effluent of each WWTW. Resistance genes were quantified in 11 isolated cultures before and after exposure to sub-MIC concentrations of target antibiotics. The numbers of ARG and ARB in both WWTW effluents were notably reduced compared to the influent. Sul1 and sul2 gene copies increased in cultures enriched in sub-MIC concentrations of sulfamethoxazole, while blaKPC decreased after exposure to amoxicillin. It was concluded, within the parameters of this study, that WWTW assist in reducing ARG and ARB, but that sub-inhibitory exposure to antimicrobials has a varied effect on ARG copy number in pure cultures.",

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author = "Keira Tucker and Wendy Stone and Marelize Botes and Feil, {Edward J.} and Wolfaardt, {Gideon M.}",

note = "Funding Information: KT was supported in part by the National Research Foundation of South Africa (Grant numbers: 118159 and 130527) and the Water Research Commission (Project No. K5/2733). WS was supported by Biogeochemistry Research Infrastructure Platform (BIOGRIP), funded by the Department of Science and Innovation of South Africa. Funding Information: The authors wish to thank Edward Archer, Mercia Volschenk, and the City of Cape Town for assisting with and permitting sampling of WWTW, the Central Analytical Facility at Stellenbosch University for DNA sequencing support, and the financial assistance from the NRF, WRC, and BIOGRIP. ",

year = "2022",

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doi = "10.3389/frwa.2022.883282",

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N2 - With their large, diverse microbial communities chronically exposed to sub-inhibitory antibiotic concentrations, wastewater treatment works (WWTW) have been deemed hotspots for the emergence and dissemination of antimicrobial resistance, with growing concern about the transmission of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) into receiving surface waters. This study explored (1) the prevalence of ARG and ARB in local WWTW, (2) the effect of sub-inhibitory antimicrobial exposure on ARG copy numbers in pure cultures from WWTW, and (3) two WWTW with different treatment configurations. For each WWTW, qPCR determined the prevalence of mcr3, sul1, sul2, and blaKPC during the treatment process, and culture methods were used to enumerate and identify ARB. Bacterial colonies isolated from effluent samples were identified by 16S rDNA sequencing and their respective minimum inhibitory concentrations (MIC) were determined. These were compared to the MICs of whole community samples from the influent, return activated sludge, and effluent of each WWTW. Resistance genes were quantified in 11 isolated cultures before and after exposure to sub-MIC concentrations of target antibiotics. The numbers of ARG and ARB in both WWTW effluents were notably reduced compared to the influent. Sul1 and sul2 gene copies increased in cultures enriched in sub-MIC concentrations of sulfamethoxazole, while blaKPC decreased after exposure to amoxicillin. It was concluded, within the parameters of this study, that WWTW assist in reducing ARG and ARB, but that sub-inhibitory exposure to antimicrobials has a varied effect on ARG copy number in pure cultures.

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Wastewater Treatment Works: A Last Line of Defense for Preventing Antibiotic Resistance Entry Into the Environment

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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Cite this

Wastewater Treatment Works: A Last Line of Defense for Preventing Antibiotic Resistance Entry Into the Environment

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Projects

ReNEW

Cite this