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Campylobacter on the Island of Ireland
Welcome to the project ‘A Study on the Distribution of Campylobacter in a Subset of Intensive Poultry Flocks on the Island of Ireland and the Identification of Possible Factors Affecting that Distribution', funded by safefood, The Food Safety Promotion Board.
Introduction
Campylobacter infection is a major public health problem. Campylobacter is the most commonly isolated bacterial cause of human gastrointestinal illness in Ireland, the UK and many countries globally with temperate climates. In 2003 there were 1,568 cases of confirmed campylobacteriosis reported in the Irish republic (crude incidence rate 39.9/100,000). This compares with data from Northern Ireland with a crude incidence rate of 43.8/100,000 in 2003.
The epidemiology of Campylobacter infection is complex. Sources and routes of transmission are not yet fully understood. The majority of Campylobacter infection is apparently sporadic. Case-control studies have identified a range of exposures. Poultry consumption has been demonstrated to be a risk factor in several studies. At a recent conference ‘Campylobacter Surveillance and Research in Ireland: The Way Ahead’, national and international experts agreed that a key area of public health protection was control of the pathogen at the primary production stage in poultry. However, information on the extent of Campylobacter colonisation of poultry flocks, and the possible factors affecting that distribution, remains a major gap in current knowledge in the Irish context.
There are currently 19 species and subspecies in the genus Campylobacter, a group of gram negative bacteria, which colonize the gastrointestinal tract of a variety of animals and birds. Campylobacter jejuni is the predominant species associated with human illness, with the remainder mostly being C. coli and C. lari.
Campylobacter species grow quite slowly and may require up to 72 hours for isolation. They are fastidious organisms requiring a microaerophilic environment for growth (3-10% carbon dioxide and 5-10% oxygen) and growth optimally at temperature between 37°C and 42°C.
Campylobacter are invasive organisms. They also produce numerous cytotoxins, the best characterised of which is the cytolethal-distending toxin (CDT), encoded by three adjacent genes cdtA, cdtB and cdtC. The expression of all three is required to produce active toxin. Although most Campylobacter infections are self-limiting, in cases of prolonged or systematic infection antibiotics may be applied. Macrolides and fluoroquinolones are the current antimicrobial agents used. Intravenous aminoglycoside therapy may also be used in more serious cases of campylobacteriosis. Campylobacters resistant to all of these agents has been demonstrated. There are 3 distinct mechanisms including:
• modification (mutation) of target genes
• acquisition of a gene encoding an enzyme which destroys the antibiotic
• efflux pump systems
The latter is of particular importance as it confers multi-drug resistance.
This project will examine the distribution of Campylobacter in a cross-section of Irish poultry farms. Sources and genetic function will be investigated in a select subset of isolates using molecular techniques. Antibiotic resistance profiles will be established. Finally the potential for controlling Campylobacter in Irish poultry, through the application of probiotics and bird stress management, will be investigated to provide the basis for reduced bird carriage, poultry meat contamination and protected public health.
Project Objective
To identify and quantify the distribution of Campylobacter colonisation in a subset of intensive poultry flocks and to identify possible factors affecting that distribution. Such knowledge will assist control measures, which should ultimately lead to reducing the adverse impact of Campylobacter on public health.
Sub-objectives:
1. To investigate the sources, distribution, routes of transmission and the genetic basis of colonisation of Campylobacter in a cross section of Irish poultry using environmental mapping and molecular characterisation techniques.
2. To elucidate antibiotic resistance profiles, identify multiple drug resistant (MDR) isolates and investigate the role of efflux pumps in MDR Campylobacter.
3. To investigate the potential for Campylobacter control in Irish poultry through the application of probiotic technologies and flock management practices.
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