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Recap of the Elo Qualité webinar: Food Safety – Fast, Optimized Environmental Monitoring
READ MORE »Campylobacter spp.: the leading cause of foodborne illness, and the hardest to culture
Campylobacter is the bacterial zoonosis most frequently reported in Europe since 2005, ahead of Salmonella. Yet it is also one of the hardest bacteria to detect reliably: fragile outside the host, it can enter a state where conventional culture methods no longer detect it, even though it remains present. Here’s the essential rundown.
Download the complete Campylobacter spp. fact sheet
A technical, summary resource designed for quality and HACCP managers:
- Why conventional culturing reaches its limits with Campylobacter
- Specific challenges on poultry farms and in slaughterhouses
- Key figures and up-to-date regulations
- Overview of detection methods
What is Campylobacter spp.?
168,396 confirmed cases in the European Union in 2024
the most reported bacterial zoonosis since 2005, ahead of Salmonella.
Source: EFSA/ECDC, The European Union One Health 2024 Zoonoses Report
Campylobacter, particularly the jejuni and coli species, is a bacterium naturally present in the digestive tract of poultry and other farm animals, without making them sick. Unlike Salmonella or Listeria, it survives poorly outside the host and does not multiply in food: it is sensitive to oxygen, desiccation, and temperature changes. This fragility might suggest it’s easy to control. It’s actually the opposite that creates the problem.
Why is Campylobacter so hard to culture?
Faced with environmental stress, such as cold, desiccation, or prolonged exposure to oxygen, Campylobacter can enter a state known as “viable but non-culturable” (VBNC). In this state, the bacterium remains alive and retains its pathogenic potential, but no longer forms colonies on the culture media used by reference methods. In practice, a sample can therefore be declared negative when the bacterium is actually present. This phenomenon has been demonstrated repeatedly in the lab, including directly within poultry farm environments.
A specific challenge on farms and in slaughterhouses
The infectious dose of Campylobacter is extremely low: a few hundred cells are enough to cause an infection. Combined with a high prevalence on poultry carcasses leaving slaughter, this low dose means even the slightest cross-contamination can be enough to make a batch non-compliant. The scalding, plucking, and evisceration steps are particularly sensitive to this risk.
What are the risks to human health?
Campylobacter most often causes diarrhea, sometimes bloody, accompanied by fever and abdominal pain. Its most feared complication remains rare but serious: Guillain-Barré syndrome, an autoimmune disease affecting the peripheral nerves, which can occur several weeks after the digestive infection.
Which products and production areas are most exposed?
Raw or undercooked poultry (main reservoir)
Raw milk and unpasteurized dairy products
Untreated water and ice
Vegetables exposed to cross-contamination in the kitchen
In food processing, the most sensitive areas are:
- Poultry slaughter lines, particularly around evisceration,
- Work surfaces where cross-contamination can occur between raw meat and food consumed with no cooking.
Regulatory framework
The European regulatory framework targets Campylobacter directly on the poultry carcass, at the most strategic point in the production chain. Since January 1, 2018, Regulation (EU) 2017/1495, which amends Regulation (EC) 2073/2005, has imposed a process hygiene criterion set at 1,000 CFU per gram on a broiler neck skin sample: above this threshold, the establishment must review its slaughter hygiene measures. This criterion reuses the same sampling plan already in place for Salmonella, which limits the sampling burden for operators.
In the United States, the USDA-FSIS introduced the agency’s first performance standards dedicated to Campylobacter in 2011, in addition to the existing standards for Salmonella. The threshold set limits the allowed positive sample rate to 10.4% on broiler carcasses, an approach built on a statistical prevalence principle rather than a per-sample quantitative threshold as in Europe.
Outside the European Union and the United States, the Codex Alimentarius serves as the international reference, with risk control guidelines throughout the chain, from farm to consumption.
How can you detect Campylobacter quickly, despite its fragility?
This is the whole paradox of Campylobacter: its fragility outside the host is precisely what complicates its detection by conventional culture methods, which can underestimate its real presence in the case of a VBNC state. A method that doesn’t depend on the bacterium’s ability to form colonies makes it possible to overcome this limitation.
How can you detect Campylobacter quickly, before it contaminates the finished product?
Campylobacter poses a particular challenge: its fragility outside the host makes it hard to culture, and environmental stress can push it into a state where it evades conventional culture methods while remaining potentially pathogenic. Rapid detection, with no enrichment, makes it possible to overcome this limitation and act before the product is contaminated.
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Recap of the Elo Qualité webinar: Food Safety – Fast, Optimized Environmental Monitoring
READ MORE »Frequently asked questions about Campylobacter
What regulatory criterion applies to Campylobacter on broiler carcasses?
Since January 1, 2018, Regulation (EU) 2017/1495, which amends Regulation (EC) 2073/2005, has imposed a process hygiene criterion for Campylobacter on broiler carcasses. The threshold set is 1,000 CFU per gram on a neck skin sample: above this, the sample is considered non-compliant. This criterion aims to limit fecal contamination occurring during slaughter. It applies to all poultry slaughterhouses, including unapproved ones, as soon as they fall within the scope of Regulation (EC) 852/2004.
Source: Regulation (EU) 2017/1495; DGAL Technical Instruction 2018-23.
Is the Campylobacter sampling plan the same as for Salmonella in poultry slaughterhouses?
Yes, the Campylobacter sampling plan follows the same method already used for the Salmonella criterion on poultry carcasses, namely a neck skin sample. This choice was made to limit the administrative burden on operators, who can reuse the same samples for both analyses. The European regulation explicitly states that samples taken for Salmonella can also be used for Campylobacter analyses. This is a practical way to share the workload for slaughterhouse quality managers.
Source: Regulation (EU) 2017/1495.
How do you control Campylobacter cross-contamination in poultry slaughterhouses?
Control begins even before the slaughterhouse, with biosecurity measures on farms aimed at reducing Campylobacter prevalence in live animals. Once at the slaughterhouse, the scalding, plucking, and evisceration steps are particularly sensitive, as they can spread the bacterium from one carcass to another if hygiene lapses. Strict separation of flows between dirty and clean zones, along with rigorous cleaning and disinfection of equipment between batches, helps limit this spread. It’s this entire chain, from farm to slaughter line, that determines compliance with the regulatory threshold of 1,000 CFU per gram.
Source: EFSA, 2012 opinion on Campylobacter; DGAL, technical instructions 2018-23 and 2021-410.
Why does Campylobacter remain hard to control despite its low resistance outside the host?
Unlike bacteria such as Listeria or Salmonella, Campylobacter survives poorly outside the digestive tract and does not multiply in food. But this fragility is offset by an extremely low infectious dose, since a few hundred cells are enough to cause an infection. Combined with a very high prevalence on poultry carcasses leaving slaughter, this low infectious dose means even minor cross-contamination can be enough to make a product non-compliant or dangerous. It’s this paradox between environmental fragility and high contagiousness that makes Campylobacter hard to eliminate completely.
Source: Eurofins France, Campylobacter fact sheet; EFSA, 2012 opinion.
Why is Campylobacter the leading cause of bacterial foodborne illness in Europe?
According to the latest European zoonoses report, campylobacteriosis accounted for 168,396 confirmed cases in 2024, or 55.3 cases per 100,000 population, making it the most frequently reported zoonosis in the European Union, a position it has held without interruption since 2005. Poultry meat remains the main identified food source, due to the bacterium’s natural presence in the digestive tract of healthy birds. This high frequency is also explained by the low infectious dose needed to develop the disease. It’s this case volume that puts Campylobacter ahead of Salmonella and Listeria in total number of cases reported each year.
Source: EFSA/ECDC, The European Union One Health 2024 Zoonoses Report.
What is the VBNC state in Campylobacter, and why is it a problem for the food industry?
The VBNC state (Viable But Non-Culturable) is a dormancy state. Campylobacter jejuni enters it when subjected to stress, and it encounters plenty of that in processing plants, especially in the poultry sector:
- refrigeration (4°C);
- freezing (−20°C to −70°C);
- exposure to atmospheric oxygen;
- acidity;
- lack of nutrients.
In this state, the bacterium changes shape: it goes from a spiral form to a round (coccoid) form and loses its flagellum. It nonetheless remains alive and its metabolism keeps functioning. Above all, it no longer grows on conventional culture media. Yet the official reference methods for detecting Campylobacter (such as ISO standard 10272) rely precisely on culturing.
This creates three problems for the industry:
- False negative results. A product or surface can be declared compliant when live Campylobacter is actually present. Real contamination is therefore underestimated.
- A persisting health risk. Under favorable conditions, particularly in the host’s intestine, VBNC cells can “wake up” and become infectious again. They partly retain their virulence genes. Non-culturable Campylobacter present in drinking water has, moreover, been able to colonize chickens.
- Overestimated cleaning and disinfection effectiveness. VBNC cells can survive these processes and contribute to recurring contamination, despite improved hygiene practices.
To better assess the risk, culturing can be supplemented with methods that measure viability, such as RNA-based methods.
Source: Pokhrel D., Thames H.T., Zhang L., et al. (2022).
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