Dissertation
Molecular pathogenesis of Escherichia coli in septicaemia and urinary tract infection
University of the Sunshine Coast, Queensland
Doctor of Philosophy, University of the Sunshine Coast
2013
DOI:
https://doi.org/10.25907/00220
Abstract
Escherichia coli is a versatile bacterium that can extend from being a commensal inhabitant of the gastrointestinal (GI) tract to causing life threatening diseases such as urinary tract infections (UTIs) and septicaemia. To understand the pathogenesis of E. coli causing UTI this study investigated virulence factors that contribute to the survival and persistence of E. coli causing extraintestinal diseases. In view of a majority of E. coli causing UTI originating from the GI tract, this thesis questioned the assumption that the urinary tract is the only source of bacterial translocation in patients with urosepsis, and investigated the potential for translocation from the GI tract. PhP typing of the strains isolated from urine and blood of patients showed that 44 out of 47 (94%) patients had identical strains in their blood and urine. Blood isolates adhered to both renal i.e. A-498 cell line and GI i.e. HT-29 cell line, although their rate of adhesion and translocation in A-498 cells was significantly higher. The three non-identical blood isolates were unable to translocate through HT-29 cells, indicating other factors such as weakened immune response of hospitalised patients may play a role in this process. To further investigate the importance of bacterial virulence in causing nosocomial infections, this thesis investigated the genetic relatedness and virulence gene (VG) profiles of uropathogenic E. coli (UPEC) in hospitalised children and adults. Random amplified polymorphic DNA (RAPD) typing resolved 6 major clusters, with two clusters consisting almost exclusively of E. coli from children. There was a higher prevalence of the genes encoding for alpha-haemolysin and capsule synthesis among the strains in this group, a factor that may be associated with renal scarring among children. E. coli isolated from adults had a higher prevalence of genes encoding for invasion and antigen 43, and were able to produce biofilm significantly more than children isolates. These results suggest that pathogenesis of UPEC in children and adults is exacerbated by the presence of specific genes.
Details
- Title
- Molecular pathogenesis of Escherichia coli in septicaemia and urinary tract infection
- Authors
- Tara L Vollmerhausen
- Contributors
- Mohammad Katouli (Supervisor)
- Awarding institution
- University of the Sunshine Coast
- Degree awarded
- Doctor of Philosophy
- Publisher
- University of the Sunshine Coast, Queensland
- DOI
- 10.25907/00220
- Organisation Unit
- University of the Sunshine Coast, Queensland; GeneCology Research Centre - Legacy; School of Health and Sport Sciences - Legacy; School of Science, Technology and Engineering; Centre for Bioinnovation
- Language
- English
- Record Identifier
- 99449810202621
- Output Type
- Dissertation
Metrics
60 File views/ downloads
769 Record Views