Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Molecular investigation of the chlorine and antibiotic resistance mechanisms of Escherichia coli isolated from natural water sources in the Western Cape
Thesis (MScMedSc (Pathology. Medical Microbiology))--University of Stellenbosch, 2009.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Stellenbosch : University of Stellenbosch
2009
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614136716754944 |
|---|---|
| access_status_str | Open Access |
| author | Krige, Marilyn |
| author2 | Wasserman, Elizabeth |
| author_browse | Krige, Marilyn Wasserman, Elizabeth |
| author_facet | Wasserman, Elizabeth Krige, Marilyn |
| author_sort | Krige, Marilyn |
| collection | Thesis |
| dc_rights_str_mv | University of Stellenbosch |
| description | Thesis (MScMedSc (Pathology. Medical Microbiology))--University of Stellenbosch, 2009. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/2779 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:47:15.075Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2009 |
| publishDateRange | 2009 |
| publishDateSort | 2009 |
| publisher | Stellenbosch : University of Stellenbosch |
| publisherStr | Stellenbosch : University of Stellenbosch |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/2779 Molecular investigation of the chlorine and antibiotic resistance mechanisms of Escherichia coli isolated from natural water sources in the Western Cape Krige, Marilyn Wasserman, Elizabeth University of Stellenbosch. Faculty of Health Sciences. Dept. of Pathology. Medical Microbiology. Water -- Purification -- Chlorine Chlorine -- Therapeutic use -- South Africa -- Western Cape Microbial contamination Dissertations -- Medical microbiology Theses -- Medical microbiology Escherichia coli e.Coli infections Water -- pollution Drug resistance in microorganisms Thesis (MScMedSc (Pathology. Medical Microbiology))--University of Stellenbosch, 2009. Water is used for various purposes and contamination can have severe implications if untreated. One of the most common and cost effective water disinfectants, especially used in developing countries, is chlorine. However, microorganisms have developed different mechanisms in response to environmental stress conditions, such as the viable but nonculturable (VBNC) effects possibly displayed in this study, enabling them to survive. Chlorine may also exert several effects on microorganisms, such as the expression of multi-substrate efflux pumps, decreased membrane permeability and transport inhibition that may lead to chlorine tolerance and antimicrobial resistance. In a descriptive and comparative study, the molecular characteristics of E. coli strains isolated from environmental waters in the Western Cape and the possible relationship between chlorination and antimicrobial resistance were investigated. Water and biofilm samples were exposed to chlorine, as well as efflux pump inhibitor (EPI) concentrations, and surviving E. coli strains were tested for their phenotypic characteristics including antimicrobial susceptibility profiles and morphological types. Candidate genes possibly involved in resistance to antimicrobials, disinfection and efflux pumps were detected with polymerase chain reaction (PCR) and sequenced. Sequencing analysis and homology searches were done and E. coli strains were typed as either Enteropathogenic E. coli strains (EPEC) or Enterotoxigenic E. coli strains (ETEC) on the presence of virulence genes. All water and biofilm sources examined were heavily polluted with E. coli, and a high enumeration level of this indicator organism of faecal contamination was recorded. Chlorine tolerance was found to be associated with antimicrobial resistance. Addition of EPI with exposure to chlorine decreased enumeration levels of these organisms, suggesting that efflux pumps may play a role in tolerance to chlorine. Several morphological patterns were described amongst the E. coli strains and a change in this was recorded after exposure to chlorine. Highly resistant antibiograms displayed by the isolated strains included ampC β-lactamase producing E. coli strains and extended spectrum β-lactamases (ESBLs). Amplification of the candidate genes selected for heatshock, oxidative stress genes and efflux pump were most frequently detected while the structural genes involved in fluoroquinolones (FQs) resistance were detected less frequently in the selected strains. Sequencing of these amplified candidate genes demonstrated various changes in amino acid sequences, including one common mutational pathway taken by E. coli when exposed to stress conditions. Further homology searches of the sequenced candidate genes illustrated similarities in 19 pathogenic and 14 non-pathogenic E. coli as well as 3 Shigella strains. Detection of virulence genes found three EPEC strains (bfpA, eaeA), two EPEC (eaeA), ten EPEC (bfpA) and one ETEC strain (st) amongst the isolates. This study underlines the need for monitoring our water sources, which poses a public health risk due to incomplete chlorination, antimicrobial resistance and the spread of clinically relevant pathogenic strains. 2009-02-25T07:18:50Z 2010-06-01T08:58:02Z 2009-02-25T07:18:50Z 2010-06-01T08:58:02Z 2009-03 Thesis http://hdl.handle.net/10019.1/2779 en University of Stellenbosch application/pdf Stellenbosch : University of Stellenbosch |
| spellingShingle | Water -- Purification -- Chlorine Chlorine -- Therapeutic use -- South Africa -- Western Cape Microbial contamination Dissertations -- Medical microbiology Theses -- Medical microbiology Escherichia coli e.Coli infections Water -- pollution Drug resistance in microorganisms Krige, Marilyn Molecular investigation of the chlorine and antibiotic resistance mechanisms of Escherichia coli isolated from natural water sources in the Western Cape |
| title | Molecular investigation of the chlorine and antibiotic resistance mechanisms of Escherichia coli isolated from natural water sources in the Western Cape |
| title_full | Molecular investigation of the chlorine and antibiotic resistance mechanisms of Escherichia coli isolated from natural water sources in the Western Cape |
| title_fullStr | Molecular investigation of the chlorine and antibiotic resistance mechanisms of Escherichia coli isolated from natural water sources in the Western Cape |
| title_full_unstemmed | Molecular investigation of the chlorine and antibiotic resistance mechanisms of Escherichia coli isolated from natural water sources in the Western Cape |
| title_short | Molecular investigation of the chlorine and antibiotic resistance mechanisms of Escherichia coli isolated from natural water sources in the Western Cape |
| title_sort | molecular investigation of the chlorine and antibiotic resistance mechanisms of escherichia coli isolated from natural water sources in the western cape |
| topic | Water -- Purification -- Chlorine Chlorine -- Therapeutic use -- South Africa -- Western Cape Microbial contamination Dissertations -- Medical microbiology Theses -- Medical microbiology Escherichia coli e.Coli infections Water -- pollution Drug resistance in microorganisms |
| url | http://hdl.handle.net/10019.1/2779 |
| work_keys_str_mv | AT krigemarilyn molecularinvestigationofthechlorineandantibioticresistancemechanismsofescherichiacoliisolatedfromnaturalwatersourcesinthewesterncape |