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Antibiotic resistance in surface waters and biofilm-response to environmental contaminants
Thesis (PhD)--Stellenbosch University, 2021.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2021
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| _version_ | 1867613816865423360 |
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| access_status_str | Open Access |
| author | Tucker, Keira |
| author2 | Wolfaardt, Gideon M. |
| author_browse | Tucker, Keira Wolfaardt, Gideon M. |
| author_facet | Wolfaardt, Gideon M. Tucker, Keira |
| author_sort | Tucker, Keira |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2021. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/123739 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:42:09.814Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/123739 Antibiotic resistance in surface waters and biofilm-response to environmental contaminants Tucker, Keira Wolfaardt, Gideon M. Botes, Marelize Feil, Edward Stellenbosch University. Faculty of Science. Dept. of Microbiology. Antibiotic resistance Water -- Surfaces -- Treatment Biofilms Wastewater treatment works Water -- Purification -- Disinfection Water quality -- Environmental aspects -- South Africa UCTD Thesis (PhD)--Stellenbosch University, 2021. ENGLISH ABSTRACT: Ensuring water security for the future has become important due to rapid urbanisation and diminishing freshwater resources. South Africa’s water resources are scarce and as a result, reclamation of alternative freshwater resources such as treated wastewater is being investigated. There is growing evidence that drinking and wastewater treatment is either non- compliant to quality standards or lacking in certain communities. In areas with no infrastructure for wastewater removal, open sewers create a health risk for humans, animals, and the environment. Poor antimicrobial stewardship, over-use and incorrect disposal has led to increased resistance to antibiotics, rendering some bacterial infections untreatable. There is a concern that sub- inhibitory concentrations of antibiotics create a selection pressure that promotes horizontal gene transfer and emergence of bacterial communities that are resistant to antibiotics. Antibiotics, antibiotic resistant bacteria (ARB), as well as other contaminants that have been shown to promote antimicrobial resistance (AMR) such as heavy metals, enter surface waters and wastewater treatment works (WWTW) in trace concentrations via multiple pathways. As a result, WWTW are deemed hotspots for the emergence and dissemination of AMR. In addition, environmental waters are home to various matrices, including biofilms that are especially problematic in a clinical setting due to their antibiotic resistant and persistent nature. The research presented in this dissertation aimed to contribute to the knowledge surrounding the abundance of ARB in WWTW and surface waters in a South African context. Although ARB and antibiotic resistance genes (ARG) were detected in WWTW effluent, the abundance of both were reduced compared to the influent, suggesting that WWTW played a role in reducing AMR in receiving waters, while exposure to sub-inhibitory concentrations of antibiotics did not result in a significant change in the number of target ARG in isolates selected as representatives of a cultured population. This was emphasised in an expanded study that monitored various regions over a year. In addition, it was shown that surface waters, biofilms and sediments influenced by anthropogenic activities from residential and industrial sectors had higher prevalence of ARB compared to samples influenced by agricultural activity. Metagenomic analysis revealed that ARG relating to efflux pumps were the most common compared to those specific for target antibiotics. Due to heavy-metals and antibiotics being present in the environment in trace concentrations, exposure of mixed-community biofilms to sub-inhibitory concentrations of these contaminants was investigated. AMR in the biofilms did not increase, but it was suggested that the sub-inhibitory exposure promoted the development of persistent mixed community biofilms. Treatment interventions are crucial for removing pollutants and AMR already present in the environment. However, with due recognition of the complexity involved when considering humans, animals, the environment and a diverse pool of contaminants, this dissertation argues the need to expand the approach for mitigation of emergence or dissemination of AMR in the environment by incorporating greater emphasis on antibiotic stewardship, policies around antibiotic usage in all sectors, and overall public awareness. AFRIKAANSE OPSOMMING: Die versekering van watersekuriteit het belangrik geword vir die toekoms as gevolg van vinnige verstedeliking en ’n afname in varswaterbronne. Na aanleiding van beperkte waterbronne in Suid-Afrika, word die herwinning van alternatiewe waterbronne soos behandelde afvalwater ondersoek. Daar is toenemend bewyse dat die behandeling van drink- en afvalwater nie aan die kwaliteits riglyne voldoen nie, of hierdie geriewe bestaan nie in sekere gemeenskappe nie. In areas sonder infrastruktuur vir die behandeling en verwydering van afvalwater, skep oop rioolwater 'n gesondheidsrisiko vir mense, diere en die omgewing. Swak antimikrobiese beheer, oorbenutting en onvoldoende verwydering van antibiotika, het gelei tot verhoogde antibiotika weerstand, wat sommige bakteriële infeksies onbehandelbaar maak. Daar is kommer dat sub-inhiberende konsentrasies van antibiotika 'n seleksiedruk skep wat horisontale geenoordrag bevorder, asook die ontstaan van antibiotika-weerstandige bakteriese (AWB) gemeenskappe. Afvalwaterbehandelingswerke (AWBW) word beskou as brandpunte vir die opkoms en verspreiding van antimikrobiese weerstand (AMW) as gevolg van antibiotika, AWB, en ander besoedelingstowwe soos swaarmetale wat AMW bevorder, wat in spoorkonsentrasies in oppervlakwater en AWBW beland via verskeie roetes. Daarbenewens, dra omgewingswater verskeie matrikse, onder andere biofilms wat veral problematies is in die kliniese veld vanweë hul antibiotika-weerstandige en hardnekkige aard. Die doel van hierdie proefskrif se navorsing was om die kennis rondom die voorkoms van AWB in AWBW en oppervlakwater in 'n Suid-Afrikaanse konteks te bevorder. Alhoewel AWB- en antibiotika-weerstandstandige gene (AWG) in AWBW-afvalwater opgespoor is, is die teenwoordigheid van albei verminder in vergelyking met die ontvangswater, wat daarop dui dat AWBW 'n rol speel in die vermindering van AMW in ontvangswater. Terselfdetyd het blootstelling aan sub-inhiberende konsentrasies van antibiotika nie gelei het tot 'n beduidende verandering in die aantal teiken AWG in isolate wat gekies is as verteenwoordigers van laboratorium gekweekte gemeenskappe nie. Hierdie is benadruk in 'n uitgebreide studie wat verskillende streke oor 'n jaar gemonitor het. Daarbenewens het oppervlakwater, biofilms en sedimente wat deur antropogene aktiwiteite beïnvloed is deur residensiële en industriële sektore, 'n hoër voorkoms van AWB getoon in vergelyking met monsters wat deur landbou- aktiwiteite beïnvloed is. Metagenomiese analise het getoon dat gene wat verband hou met uitvloeipompe die mees algemene AWG was in vergelyking met dié wat vir spesifiek antibiotika geteiken was. As gevolg van die teenwoordigheid van spoorkonsentrasies van swaar metale en antibiotika in die omgewing, is die blootstelling van gemende-gemeenskap biofilms aan sub-inhiberende konsentrasies van hierdie besoedelstowwe bestudeer. AMW in biofilms het nie verhoog nie, maar dit was voorgestel dat die sub-inhiberende blootstelling die ontwikkeling van hardnekkige gemengde gemeenskaps biofilms bevorder het. Behandelingsintervensies is van kardinale belang vir die verwydering van besoedelingstowwe en AMW wat reeds in die omgewing voorkom. Met voldoende erkenning aan die kompleksiteit verbonde met mense, diere, die omgewing, en 'n diverse mengsel van kontaminante, benadruk hierdie proefskrif dat die voorkoms en verspreiding van AMW in die omgewing moet verlaag word deur groter klem te lê op antibiotika-bestuur beleid rakende die gebruik van antibiotika in alle sektore, asook algemene publieke bewustheid. Doctoral 2021-11-08T11:28:24Z 2021-12-22T14:18:43Z 2021-11-08T11:28:24Z 2021-12-22T14:18:43Z 2021-12 Thesis http://hdl.handle.net/10019.1/123739 en_ZA Stellenbosch University xix, 145 pages : illustrations (some color), maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Antibiotic resistance Water -- Surfaces -- Treatment Biofilms Wastewater treatment works Water -- Purification -- Disinfection Water quality -- Environmental aspects -- South Africa UCTD Tucker, Keira Antibiotic resistance in surface waters and biofilm-response to environmental contaminants |
| title | Antibiotic resistance in surface waters and biofilm-response to environmental contaminants |
| title_full | Antibiotic resistance in surface waters and biofilm-response to environmental contaminants |
| title_fullStr | Antibiotic resistance in surface waters and biofilm-response to environmental contaminants |
| title_full_unstemmed | Antibiotic resistance in surface waters and biofilm-response to environmental contaminants |
| title_short | Antibiotic resistance in surface waters and biofilm-response to environmental contaminants |
| title_sort | antibiotic resistance in surface waters and biofilm response to environmental contaminants |
| topic | Antibiotic resistance Water -- Surfaces -- Treatment Biofilms Wastewater treatment works Water -- Purification -- Disinfection Water quality -- Environmental aspects -- South Africa UCTD |
| url | http://hdl.handle.net/10019.1/123739 |
| work_keys_str_mv | AT tuckerkeira antibioticresistanceinsurfacewatersandbiofilmresponsetoenvironmentalcontaminants |