Investigation of pathogenic vibrio in Irish aquaculture
Boyle, Katie Louise
Boyle, Katie Louise
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Publication Date
2023-07-31
Type
Thesis
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Abstract
Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio cholerae are marine pathogens that cause gastroenteritis in humans after the consumption of infected shellfish. Vibrio can cause devastating losses of oysters, shrimps and other aquaculture shellfish. Climate change is causing a wider distribution of these bacteria due to warming of marine waters which favours their growth and is of concern for shellfish producers in Ireland. Gastroenteritis due to Vibrio is of increasing concern in the EU, and the EU has identified Vibrio species as emerging pathogens posing a serious threat to human health. The aim of this work was to assess the risk of pathogenic Vibrio spp. to shellfish aquaculture and human health in Ireland. A combination of culture, molecular and genetic approaches were used to detect, identify and enumerate pathogenic Vibrio spp. across five large scale aquaculture farms in Ireland. Samples of shellfish, water and sediment were collected over a 12-month period, along with monitoring of environmental factors including sea surface temperature, pH and salinity at each location. This research resulted in the detection of human pathogenic V. parahaemolyticus, in four aquaculture sites in Ireland. V. cholerae and V. vulnificus were not detected. Isolates were sequenced via whole genome sequencing, confirming the presence of drug resistance genes and virulence genes, including type three secretion system two genes along with a hemolysin gene trhX, a homologue of the tdh-related hemolysin trh, considered a major virulence factor. Multi-locus sequence typing of these isolates detected four novel sequence types within Irish V. parahaemolyticus isolates. We identified five additional Vibrio spp., along with three non-target Vibrio spp., one of which was a novel Grimontia spp. These results report the first isolation of Vibrio spp., most importantly pathogenic V. parahaemolyticus, from Irish aquaculture farms and highlight a diverse range of Vibrio spp. inhabiting aquaculture sites in Ireland.
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NUI Galway