Campylobacter are gram-negative, non-spore-forming spiral-shaped bacteria. They grow under microaerobic conditions (reduced oxygen content), are sensitive to acidic and basic pH values, are safely killed by pasteurisation. The most common species are C. jejuni, which causes about 90 % of human cases of illness (campylobacteriosis), and C. coli.

Campylobacter infections are widespread worldwide and occur more frequently during the warm season. Alongside salmonellae, they are the most important pathogens of bacterial intestinal diseases in humans. As in previous years, campylobacteriosis was the most frequently reported foodborne bacterial infectious disease in Austria in 2022.

Poultry, pigs, cattle, domestic animals such as dogs and cats, and wild animals, especially birds, can be carriers of Campylobacter. These germs are possible intestinal inhabitants of these animals, in which they rarely cause disease.

Campylobacteriosis in humans is mainly considered to be a food-borne infection. The main sources of infection are primarily inadequately heated poultry meat, unheated food contaminated with it (e.g. after using the same cutting board without thorough cleaning after cutting up the poultry) and raw milk. Direct transmission from person to person (faecal-oral) is rare.

Usually 2 to 5 days, depending on the number of germs ingested.

Illness can be manifested by high fever, watery to bloody diarrhea, abdominal pain, headache and fatigue; the disease can also be asymptomatic, i.e. without any recognizable signs of illness. The disease lasts on average a few days to a week, occasionally longer. Consequences can include joint diseases (e.g. reactive arthritis) and Guillain-Barré syndrome (GBS), in which paralysis of the peripheral nerves occurs.

As a rule, an illness is self-limiting and balancing the water and electrolyte balance is sufficient as therapy. Infants and patients who develop high fever or are immunocompromised can be treated additionally with antibiotics.

The seasonal occurrence of campylobacteriosis showed a similar pattern in the past years: the fewest cases of illness between November and April, most cases from June to September. The isolation rates of thermotolerant Campylobacter from slaughtered broiler flocks provide a roughly similar picture, with the highest values in the summer months, which subsequently suggest higher contamination rates of fresh retail chicken meat in summer and thus point to this food as the most important pathogen vehicle for Campylobacter.

AGES Wissen aktuell: Topic Report Campylobacter 2021

In 2023, approx. 450 food samples (official tests according to the sample plan) were tested for Campylobacter, primarily poultry meat and poultry meat preparations (approx. 360 samples), ready-to-eat food (approx. 30 samples) and raw milk (50 samples). For the first time, insects (intended for human consumption) were also analysed for Campylobacter, but none of the 11 samples were detected.

Campylobacter was detected in 173 samples, 134 of which were in fresh chicken meat (n=185). Campylobacter was detected twice in fresh turkey meat (16 samples analysed). Depending on the time of year, the positivity rate for fresh chicken meat is therefore approx. 70 %, which corresponds to the proportion in previous years. Campylobacter was not detectable in raw milk and other foods. Beef and pork are only rarely analysed because Campylobacter generally does not survive due to the production conditions (different slaughtering process; this meat is matured, the meat surface dries out) and therefore these foods only play a minor role as a source of infection for humans.

The process hygiene criterion "Campylobacter" (regulated in Commission Regulation (EU) 2017/1495 (within the framework of Regulation (EU) 2073/2005, microbiological criteria) has been in force in Austria since 1 January 2018. A total of 978 samples were taken in Austrian broiler slaughterhouses for the purpose of self-monitoring. Of these, Campylobacter ≥1,000 CFU/g was detected in 134 samples.

Since 2004, annual monitoring programs have been carried out in Austria by the federal government, together with commissioned veterinarians and AGES, in accordance with the Monitoring Programs Regulation with regard to selected pathogens in cattle, sheep, pigs and chickens. In 2014, a new EU implementing decision came into force that requires broiler and turkey flocks to be tested every 2 years for the presence of thermotolerant Campylobacter and the isolated C. jejuni to be tested for their susceptibility to antibiotics. In 2015, 2017, and 2019, poultry did not need to be tested for Campylobacter; in 2018, the prevalence of thermotolerant Campylobacter was 55.5% in broiler flocks and 54.9% in turkey flocks. In both broiler and turkey flocks, the prevalence decreased to below 50% in 2020.

Diagnostics: The pathogen is usually detected by culturing stool. At the national reference centre for Campylobacter we perform the following tests:

• Species/genus differentiation of Campylobacter and related genera (biochemical, MALDI-TOF, PCR, sequencing).
• Antibiotic resistance testing: Determination of the resistance of isolates from humans, animals, food and the environment to clinically relevant or epidemiologically important antibiotics on the basis of the minimum inhibitory concentration.
• Performance of tasks in the framework of the Zoonoses Monitoring Directive 2003/99/EC
• Molecular biological fine typing (by means of PFGE, MLST) of isolates in the context of laboratory-based infection epidemiological clarification of infection sources and routes
• Qualitative and quantitative detection of Campylobacter in foodstuffs

We also maintain a strain collection (human, veterinary, feed and food isolates), perform proficiency testing and offer consulting services.

Fresh cultures in Amies transport medium with activated charcoal are best for shipping strains. It is essential that pure cultures are sent. Submissions should always be accompanied by the origin of the isolates and the necessary clinical and epidemiological data. Please use the corresponding submission form.