Profile on "Campylobacter" ("Thermotolerant Campylobacter")

General Information and Origin

Bacteria of the genus Campylobacter are heat-sensitive germs, some of which cause intestinal infections, usually with abdominal pain, vomiting, and diarrhea. Further complications are rare but can occur (e.g., infection of other organs and joint inflammation).

The most important pathogenic species for humans are C. jejuni and C. coli, with the minimum infectious dose ranging from 100 to 1,000 germs. These species belong to the thermotolerant Campylobacter. Transmission to humans mainly occurs through raw or undercooked poultry meat, poultry offal, and raw milk, but also through cross-contamination. The bacteria are found in the intestinal tract of numerous animals (warm-blooded wild, farm, and domestic animals).

Importance

Due to the heat sensitivity of these bacteria, effective killing is assured by heating steps of at least +72 °C for a minimum of 2 minutes. They can survive in vacuum packs or under a protective atmosphere and at chilling temperatures for several weeks. In food, reproduction typically does not occur. However, this is not a condition to pose a health hazard, as even low germ counts can cause illness.

Campylobacter gastroenteritis has been the most common cause of bacterial food infections in Germany and many other European countries for years.

Important Causes of Elevated Germ Counts

• Insufficient heating of food
• Cross-contamination between raw and processed foods
• Hygiene errors during manufacture (e.g., contaminated work tools, surfaces, and equipment,...)
• Processing of contaminated raw materials (particularly poultry meat is relatively frequently contaminated)
• Contamination of vegetables and other plant-based foods through fertilizers or contaminated water

Growth Conditions

• Temperature: Growth at 25 – 47 °C
• pH value: Growth at 4.9 – 9.0
• aw value: Growth down to min. 0.98
• Salt tolerance: 0.16 – 1.55 %, but strongly influenced by temperature and pH value
• Oxygen requirement: microaerophilic, growth only under a reduced oxygen atmosphere

At What Temperatures Do These Microorganisms Die?

Generally, it can be assumed that these bacteria are killed by heating to +72 °C for at least two minutes or by an equally effective process. In food, it should be ensured that this temperature-time combination is reached in the core of the product to safely kill the bacteria.

Further Information and Literature

• www.rki.de: under "Infectious Diseases A-Z"
• www.bfr.bund.de: under "Food Safety"
• www.lgl.bayern.de: under "Food" and then "Hygiene"
• Pathogenic Microorganisms: Campylobacter Volume II, G. /F. Reich Behr’s Publishing, 1st Edition 2013
• Food Microbiology, J. Krämer and A. Prange, 7th Edition 2017
• Microorganisms in Food, H. Keweloh, 2nd Edition 2008
• Handbook of Food Hygiene, K. Fehlhaber/J. Kleer/F. Kley (Behrs Publishing), 1st Edition 2007
• Information Sheet "Safely Catered - Particularly Sensitive Population Groups in Community Facilities", Federal Institute for Risk Assessment, Berlin 2017