Infectious Diseases 2022

Infectious Diseases 2022

Prevalence and levels of Campylobacter in broiler chicken in Ireland in 2017–2018

International Journal of Food Microbiology 372 (2022) 3 May, 2022

An up-to-date data on Campylobacter carriage and carcass contamination in Irish broilers - a new study. Monthly samples were collected from the three largest broiler processing plants in Ireland over a twelve-month period. Samples were taken from both first and final thin birds (partial and full depopulation) from 358 batches of broilers. From each batch, a composite sample of 10 caecal contents (n = 358) and 5 neck skins (n = 1790) were collected and numbers of Campylobacter in each sample were determined. Of the 1790 neck skin samples tested, 53% were Campylobacter positive.
Campylobacter was detected in the caecal contents of 66% of all batches tested. Depopulation and/or age had a significant effect on Campylobacter prevalence with 67% of final thin broilers yielding Campylobacter-positive neck skin samples in contrast to 38% of first thin broilers that yielded positive neck skin samples (P ≤0.002).
A significant seasonal variation was observed in the rate of Campylobacter-positive caecal samples with higher prevalence seen in July (85%) than the colder months of November (61%), December (50%), January (61%) March (57%) and April (59%). Neck skin samples were 7 times more likely to be Campylobacter positive if the caecal contents from the same batch were positive (odds ratio = 7.1; P ≤ 0.0001).
Variability between processors needs to be considered as this can impact reliable Campylobacter monitoring. The differences observed between the processing plants could be due to several factors during the slaughtering process. Improper cleaning and hygiene practices in the abattoirs during the slaughter process can lead to increased Campylobacter contamination. Carcasses in the present study were at a higher risk of being contaminated by Campylobacter later in the working day afternoon/evening) than earlier (early/mid-morning). This could possibly be explained by the occurrence of Campylobacter contamination of the machinery from contaminated batches slaughtered earlier in the same day.
The decrease in Campylobacter prevalence observed in neck skin and caecal contents demonstrates the improvements and progress made in reducing prevalences of this important enteropathogen in the Irish poultry industry since the 2008 EU baseline survey:
83.1% Campylobacter prevalence in broiler batches (n = 394) and 98.3% of carcasses (n = 394) being contaminated with Campylobacter at the end of the slaughter process.
The study provides further supporting data on the impact of thinning, the processing environment and season on Campylobacter prevalence.