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      Streptococcus equi subsp. zooepidemicus in New Zealand horses

      Patty, Olivia Anne
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      thesis.pdf
      Main text, 7.382Mb
      Table S2.1 Details of NZ Isolates.xlsx
      Supplementary material, 85.79Kb
      Table S2.2 szp Accession Numbers.xlsx
      Supplementary material, 11.81Kb
      Table S2.3 MLST STs Used.xlsx
      Supplementary material, 10.31Kb
      File S3.1 Preliminary Trials of Invasion Assay.docx
      Supplementary material, 35.10Kb
      Table S4.1 NZ Isolate Sequencing Details.xlsx
      Supplementary material, 23.26Kb
      Table S4.2 Global S. zooepidemicus Isolates.xlsx
      Supplementary material, 18.37Kb
      Table_S4.3_BAGEL4_bacteriocin_details.xlsx
      Supplementary material, 13.32Kb
      Table S4.4 NZ Gene Presence Absence.xlsx
      Supplementary material, 1.384Mb
      Table S4.5 Global Gene Presence Absence.xlsx
      Supplementary material, 2.372Mb
      Dataset S4.1 Scoary NZ Results.xlsx
      Supplementary material, 61.17Kb
      Dataset S4.2 Scoary Global Results.xlsx
      Supplementary material, 166.5Kb
      Citation
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      Patty, O. A. (2020). Streptococcus equi subsp. zooepidemicus in New Zealand horses (Thesis, Doctor of Philosophy (PhD)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/14256
      Permanent Research Commons link: https://hdl.handle.net/10289/14256
      Abstract
      Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is an opportunistic commensal bacterium of the horse mucosa causing disease in susceptible populations. This research sets out to enhance the understanding of S. zooepidemicus infections within the New Zealand horse population through strain-associated genomic and phenotypic characteristics. Retrospectively, S. zooepidemicus is the second most frequently isolated bacterium in New Zealand horses, being mainly associated with respiratory and urogenital tract infections. However, it also has the ability to colonise and or infect a diverse range of other anatomical regions of New Zealand horses. S. zooepidemicus isolates were shown to be genetically diverse via strain typing using either the single polymorphic gene, szp or standard multilocus sequence typing (MLST). Both typing schemes were shown to lack the discriminatory power needed to completely separate the isolates which was resolved by employing core genome MLST. Importantly, none of these typing methods could link a particular strain to disease status or anatomical region. However, when disease occurred the number of colonising strains tended to reduce to just the infective strain, indicating bacterial competition and strain fitness advantages. Factors available to S. zooepidemicus to colonise and persist in the horse include biofilm formation and cellular invasion with the majority of strains tested in vitro, able to form biofilms and all tested strains capable of invasion.

      Bioinformatic analysis showed that the pangenome of S. zooepidemicus is open, which demonstrates the ability of species to accessorise its genome enabling the species to diversify and exploit different hosts and environment. An average of 45 new genes are discovered with the addition of each new genome. Unfortunately, no single feature of the accessory genome analysed was able to differentiate the New Zealand horse S. zooepidemicus strains as commensals or pathogens or differentiate strains from respiratory disease or uterine infection. As a result, this study defines S. zooepidemicus as an opportunistic pathogen that can reside in the healthy equine population and infect susceptible hosts and are not anatomically, geographically or host bound.
      Date
      2020
      Type
      Thesis
      Degree Name
      Doctor of Philosophy (PhD)
      Supervisors
      Cursons, Raymond T.
      McDonald, Ian R.
      Publisher
      The University of Waikato
      Rights
      All items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
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