Date of Award


Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy


Biological Sciences

First Advisor

Dr. Brigid Lucey

Second Advisor

Dr. Roy Sleator


Campylobacter ureolyticus has been identified in a large proportion of diarrhoeal samples from patients in Ireland. However, the source of human infections has not been established and little is currently known about the potential reservoirs of C. ureolyticus in nature.

The aim of this project was to investigate a range of environmental and animal samples for the presence of this emerging pathogen using a molecular approach, to support the hypothesis of its zoonotic origin.

During the study, C. ureolyticus was detected in 30 out of 1,254 (2.4%) human diarrheic samples and isolated from 11 patients, describing, to the best of our knowledge, the first isolation of this organism from patients suffering from gastroenteritis.

This study has also identified for the Inst time, the presence of ureolyticus in various animals. A total of 32% of eats, 9% oi' dogs, 18% of pigs and 5% cows faecal samples were positive, indicating the zoonotic potential of this species. Moreover, the organism was identified in 11.7% of unpasteurized cow milk samples with an increase seen during the calving season.

Isolates of C. ureolyticus from symptomatic and asymptomatic humans and animal sources were characterized and compared. The strains showed variation on the genetic and phenotypic level, suggesting large heterogeneity and possible differences in their virulence potential.

The current study also isolated a novel Campylobacter species, closely related to ureolyticus, from lion-tailed macaques. The species, named C. corcagiensis, was extensively characterized using phenotypic and genotypic methods, such as whole genome sequencing, resulting in its establishment as a valid, novel species within the Campylobacter genus.

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