Evaluating antimicrobial resistance profiles, UV response, and curli production in Gram-negative river water isolates from the Cape Winelands

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dc.contributor.advisorSigge, G. O.en_ZA
dc.contributor.advisorLamprecht, Corne en_ZA
dc.contributor.advisorRip, Diane en_ZA
dc.contributor.authorKuster, Margot Ellenen_ZA
dc.contributor.otherStellenbosch University. Faculty of Agrisciences. Dept. of Food Science.en_ZA
dc.date.accessioned2024-03-04T16:01:35Z
dc.date.accessioned2024-04-26T19:37:06Z
dc.date.available2024-03-04T16:01:35Z
dc.date.available2024-04-26T19:37:06Z
dc.date.issued2024-03
dc.descriptionThesis (MScFoodSc)--Stellenbosch University, 2024. en_ZA
dc.description.abstractENGLISH ABSTRACT: Resistance by pathogenic microorganisms to antimicrobial agents is rising, posing a threat to human health. Aquatic environments provide the ideal setting for the dissemination and acquisition of antibiotic resistance. Following contamination via irrigation water, fresh produce becomes an ideal vector for the spread of pathogenic and antibiotic resistant microorganisms. Globally, increased consumption of these often untreated foods raises the risk of foodborne illness and exposure to antibiotc residues. Water from certain rivers used for the irrigation of fresh produce in the Cape Winelands region has been identified as unsuitable for irrigation, with faecal coliform concentrations exceeding guidelines. Additionally, studies have identified antibiotic and multidrug resistant bacteria in these waters. Treatment of contaminated waters before irrigation is thus necessary. Ultraviolet (UV) irradiation has successfully inactivated pathogenic microorganisms, but its efficacy on antibiotic resistant bacteria varies. Litle is known about the impact of irradiation on the antibiotic resistance profiles of resistant bacteria, or how photoreactivation and dark repair influence these bacteria. Similarly, while surface adhesion and self-aggregation structures are thought to reduce efficacy in UV treatment of waters, limited literature is available to substantiate these claims. This study, therefore, aimed to establish extensive antibiotic resistance profiles of bacterial river water isolates from certain rivers sites in the Cape Winelands region and to determine the impact of UV irradiation on the antibiotic resistance profiles of these river water isolates. It also aimed to identify the presence of curli (a surface adhesion structure) within isolates to understand whether these may influence UV treatment. Extended-spectrum beta-lactamase (ESBL)-producers isolated by Oosthuizen (2022) originating from the Mosselbank, Franschhoek, Plankenburg, Eerste, and Jonkershoek rivers, and isolates exhibiting UV resistance following a recovery period isolated by Jankowitz (In press) from two locations on the Berg river and one location on the Eerste river were investigated. Bacterial identification testing revealed a prevalence of Escherichia coli in the rivers. Antibiotic susceptibility testing to 19 antibiotics revealed that ESBL-producers exhibited greater antibiotic resistances when compared to non-producers, and a link between ESBL- production and multidrug resistance (MDR) could be established. Resistances to ‘critically important’ and ‘highly important’ antimicrobials for human medicine, as classified by the WHO, were prevalent in both sets of isolates indicating potential misuse of these antimicrobials in the region. A subset of ESBL-producing E. coli with heightened antibiotic resistance (n=6), and non ESBL- producing E. coli with heightened antibiotic susceptibility which had previously exhibited UV resistance qualities (n=7) were further investigated. Isolates underwent an 80 mJ.cm⁻² low-pressure UV treatment followed by a recovery period, which yielded good log₁₀CFU.mL⁻¹ reductions (mean log₁₀CFU.mL⁻¹ reduction = 6.68). Survival following recovery was low, but results exhibited a trend of increased survival following light recovery when compared to dark recovery. Post-treatment enrichment was found to promote growth in isolates exhibiting low counts. UV irradiation at 80 mJ.cm⁻² had little impact on the antibiotic susceptibility profiles of the isolates, but changes in resistances to ‘critically’ and ‘highly’ important antimicrobials were seen. A high prevalence of curli fibre production was detected in the more antibiotic resistant ESBL-producing E. coli. Curli-producing isolates expressed curli at both 37°C and 26°C, a critical finding given the typical high summer temperatures and reliance on irrigation in the Cape Winelands region during the spring and summer seasons. Overall, the study confirmed the presence of antibiotic and multidrug resistance in bacteria isolated from certain rivers used for irrigation of fresh produce in the Cape Winelands region. UV irradiation at 80 mJ.cm⁻² was found to be a feasible water treatment technique to reduce E. coli concentrations to within irrigation water guidelines. While recovery was low in the isolates after UV treatment, findings highlight the need to consider the potential for recovery during storage and distribution. The link identified between antibiotic resistance and curli production in E. coli is concerning as irrigation using waters containing curli- producers could result in a heightened risk of exposure of fresh produce consumers to antimicrobial resistant bacteria.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Weerstandigheid van patogene mikroörganismes teen antimikrobiese middels neem toe, wat 'n bedreiging vir menslike gesondheid inhou. Akwatiese omgewings bied die ideale omgewing vir die verspreiding en verkryging van antibiotika weerstandstandigheid. Na besoedeling deur besproeiingswater word vars produkte 'n ideale vektor vir die verspreiding van patogeniese en antibiotika-weerstandige mikroörganismes. Wêreldwyd verhoog die verbruik van hierdie dikwels onbehandelde kosse die risiko van voedselgedraagde siektes en blootstelling aan antibiotika-reste. Water van sommige riviere wat vir die besproeiing van vars produkte in die Kaapse Wynlandstreek gebruik word, is geïdentifiseer as ongeskik vir besproeiing, met fekale koliforme konsentrasie wat die riglyne oorskry. Daarbenewens het studies antibiotika- en multimiddelweerstandige bakterieë in hierdie waters geïdentifiseer. Behandeling van gekontamineerde water voor besproeiing is dus nodig Ultraviolet (UV)-bestraling het patogene mikroörganismes suksesvol geïnaktiveer, maar die doeltreffendheid daarvan op antibiotika-weerstandige bakterieë verskil. Min is bekend oor die impak van bestraling op die antibiotika weerstandsprofiele van weerstandbiedende bakterieë, of hoe fotoreaktivering en donker-herstel hierdie bakterieë beïnvloed. Net so, terwyl oppervlakadhesie en selfaggregasiestrukture vermoedelik doeltreffendheid in UV behandeling van water verminder, is beperkte literatuur beskikbaar om hierdie bewerings te staaf. Die studie het dus ten doel gehad om uitgebreide antibiotika-weerstandsprofiele van bakteriële rivierwaterisolate vanaf sommige riviere in die Kaapse Wynlandstreek vas te stel en om die impak van UV bestraling op die antibiotikaweerstandsprofiele van hierdie rivierwaterisolate te bepaal. Dit het ook ten doel gehad om die teenwoordigheid van “curli” (‘n oppervlakadhesiestruktuur) binne isolate te identifiseer om te verstaan of dit UV behandeling kan beïnvloed. Uitgebreide-spektrum beta-laktamase (ESBL)-produsente geïsoleer deur Oosthuizen (2022) afkomstig van die Mosselbank-, Franschhoek-, Plankenburg-, Eerste- en Jonkershoekriviere, en isolate wat UV weerstand getoon het en geïsoleer is na 'n herstelperiode deur Jankowitz (in pers) vanaf twee liggings aan die Bergrivier en een ligging aan die Eersterivier is ondersoek. Identifikasietoetse het 'n voorkoms van Escherichia coli in die riviere bevestig. Antibiotiese vatbaarheidstoetse vir 19 antibiotika het aan die lig gebring dat ESBL-produsente groter antibiotikaweerstandighede toon in vergelyking met nie-produsente. 'n Verband tussen ESBL-produksie en multimiddelweerstandigheid (MDR) kon ook vasgestel word. Weerstand teen 'kritiek belangrike' en 'hoogs belangrike' antimikrobiese middels vir menslike medisyne, soos deur die WGO geklassifiseer, was algemeen in beide stelle isolate, wat moontlike misbruik van hierdie antimikrobiese middels in die streek aandui. 'n Seleksie van ESBL-produserende E. coli met verhoogde antibiotiese weerstand (n=6), en nie-ESBL- produserende E. coli met verhoogde antibiotika vatbaarheid wat voorheen UV weerstandseienskappe getoon het (n=7) is verder ondersoek. Isolate het 'n 80 mJ.cm⁻² laedruk UV behandeling ondergaan gevolg deur 'n herstelperiode, wat goeie log₁₀CFU.mL⁻¹ verlagings opgelewer het (gemiddelde log₁₀CFU.mL⁻¹ verlaging = 6.68). Oorlewing na herstel was laag, maar resultate het 'n neiging getoon van verhoogde oorlewing na lig- herstel in vergelyking met donker-herstel. Daar is gevind dat na-behandeling verryking groei bevorder in isolate wat lae tellings toon. UV bestraling by 80 mJ.cm⁻² het min impak op die antibiotika vatbaarheidsprofiele van die isolate gehad, maar veranderinge in weerstand teen sommige 'krities' en 'hoogs' belangrike antimikrobiese middels is gesien. 'n Hoë voorkoms van “curli” produksie is opgemerk in die meer antibiotika-weerstandige ESBL-produserende E. coli. “Curli”produserende isolate het “curli” by beide 37°C en 26°C uitgedruk, 'n kritieke bevinding gegewe die tipiese hoë somertemperature en behoefte aan besproeiing in die Kaapse Wynlandstreek gedurende die lente- en somerseisoene. In die geheel het die studie die teenwoordigheid van antibiotika- en multimiddelweerstand in bakterieë wat geïsoleer is uit sommige riviere wat vir besproeiing van vars produkte in die Kaapse Wynlandstreek gebruik is, bevestig. Daar is gevind dat UV bestraling by 80 mJ.cm⁻² 'n haalbare waterbehandelingstegniek is om E. coli-konsentrasies te verminder tot binne besproeiingswaterriglyne. Terwyl herstel laag was in die isolate na UV behandeling, beklemtoon bevindinge die belangrikheid om die potensiaal vir herstel tydens berging en verspreiding te oorweeg. Die verband wat tussen antibiotika weerstandigheid en “curli” produksie in E. coli geïdentifiseer is, is kommerwekkend aangesien besproeiing met water wat “curli” produsente bevat, 'n verhoogde risiko van blootstelling van varsprodukteverbruikers aan antimikrobiese weerstandbiedende bakterieë tot gevolg kan hê.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentxix, 134 pages : illustrations (some color), maps
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130493
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshDrug resistance in microorganismsen_ZA
dc.subject.lcshPathogenic microorganismsen_ZA
dc.subject.lcshAntibiotic residuesen_ZA
dc.subject.lcshWater -- Purification -- South Africa -- Cape Winelandsen_ZA
dc.subject.lcshultraviolet (UV) irradiationen_ZA
dc.subject.lcshIrrigation water -- Qualityen_ZA
dc.subject.lcshMultidrug resistanceen_ZA
dc.subject.lcshRivers -- South Africa -- Cape Winelands regionen_ZA
dc.subject.lcshIrrigation efficiency -- South Africa -- Western Capeen_ZA
dc.subject.lcshWater quality management -- South Africa -- Western Capeen_ZA
dc.subject.nameUCTDen_ZA
dc.titleEvaluating antimicrobial resistance profiles, UV response, and curli production in Gram-negative river water isolates from the Cape Winelandsen_ZA
dc.typeThesisen_ZA
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