External contamination of broilers by Campylobacter spp. increases from the farm to the slaughterhouse

ABSTRACT

1. In this study, classical and molecular microbiological methods for detection and quantification of Campylobacter spp. were used to estimate their prevalence in faecal samples and skin swabs collected from 31 broiler flocks (20 farms) in Portugal, and measure the impact of transport-related factors on the expected rising excretion rates from the farm to the slaughterhouse.

2. Data on husbandry practices and transport conditions were gathered, including time in transit, distance travelled or ante-mortem plant-holding time.

3. A generalised linear mixed model was used to evaluate the significance of a potential post-transport rise in Campylobacter spp. counts and to assess risk determinants.

4. At least one flock tested positive for Campylobacter spp. in 80% of the sampled farms. At the slaughterhouse, Campylobacter spp. were detected in all faecal samples, C. jejuni being the most commonly isolated.

5. A post-transport rise of Campylobacter spp. counts from skin swabs was observed using classical microbiological methods (from a mean of 1.43 to 2.40 log₁₀ CFU/cm²) and molecular techniques (from a mean of 2.64 to 3.31 log₁₀ genome copies/cm²).

6. None of the husbandry practices or transport-related factors were found to be associated with Campylobacter spp. counts.

7. This study highlights the need for more research to better understand the multi-factorial nature of Campylobacter spp., a public health threat that was found to be highly prevalent in a sample of Portuguese poultry farms.

KEYWORDS:

• Broilers
• Campylobacter
• transport
• risk determinants
• slaughter
• microbiology

Acknowledgments

The authors gratefully acknowledge the farm owners and their staff as well as the slaughterhouse operatives and technical managers for their kind cooperation. The authors are grateful to Professor Adriano Bordalo and Sónia Azevedo (ICBAS-Universidade do Porto, Porto, Portugal) for their technical assistance. This study has been partially supported by the project INNOVMAR – Innovation and Sustainability in the Management and Exploitation of Marine Resources (reference NORTE-01- 0145-FEDER- 000035, within Research Line INSEAFOOD/NOVELMAR), supported by North Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). The funding institutions had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the European Regional Development Fund [NORTE-01- 0145-FEDER- 000035].