Profile of Pathogenic Yersinia (e.g., Yersinia enterocolitica) 

General Information and Origin

Yersinia enterocolitica is one of the most common causes of foodborne gastrointestinal infections in Germany and the EU.
These bacteria are often found in pigs, particularly in the tonsils, lymph nodes, and intestines of pigs, but also in pets and our environment (soil, surface water).

Significance

The presence of Yersinia enterocolitica (or pathogenic Yersinia) in ready-to-eat foods is critical as they can potentially cause illnesses. In addition to typical symptoms of food infections such as diarrhea, abdominal pain, vomiting, and fever, chronic joint inflammations can also result from a yersiniosis in rare cases.
This disease is most commonly associated in Germany with the consumption of raw pork products (e.g., minced pork).
It should also be considered that some pathogenic Yersinia strains can still multiply at refrigeration temperatures of +4 °C.

Main Causes of Contaminations

• Poor slaughter hygiene
• Cross-contamination between raw and processed foods due to hygiene errors (e.g., personnel, work tools)
• Hygienic quality of raw materials
• Insufficient heating of food

Growth Conditions

• Temperature: Growth at -1.3 – 43 °C
• pH: Growth at 4.2 - 9.6
• aw-value: Growth up to min. 0.97
• Salt tolerance: max. 5%
• Oxygen requirement: Growth under aerobic and anaerobic conditions

At what temperatures do these microorganisms die?

Generally, it can be assumed that these bacteria are killed when heated to +72 °C for at least two minutes or by an equally effective process. In foods, it's important to note that this temperature-time combination must be 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: Zoonoses, W. Heeschen (Behr's Verlag), 2nd edition 2012
• Food Microbiology, J. Krämer and A. Prange, 7th edition 2017
• Microorganisms in Food, H. Keweloh, 2nd edition 2008
• Manual of Food Hygiene, K. Fehlhaber/J. Kleer/F. Kley (Behrs Verlag), 1st edition 2007
• Leaflet "Safely Catered – Especially Vulnerable Groups in Community Facilities," Federal Institute for Risk Assessment, Berlin 2017

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Profile of Thermotolerant Campylobacter (especially Campylobacter jejuni)

General and Origin

Thermotolerant Campylobacter or Campylobacter jejuni are the most common causes of bacterial foodborne infections in Europe.

These bacteria are particularly widespread in poultry or poultry meat. But Campylobacter spp. also occurs regularly in other animal species such as cattle, sheep, and pigs.

Significance

Thermotolerant Campylobacter or Campylobacter jejuni is a frequent cause of foodborne infections. The main causes are the consumption of insufficiently heated poultry meat, the consumption of raw milk, and cross-contamination between raw and ready-to-eat foods.

The symptoms of campylobacteriosis include severe abdominal pain, watery-bloody diarrhea, vomiting, headaches, and fever.
Compared to other foodborne illnesses, such as salmonellosis, the course of campylobacteriosis is more prolonged and severe. In rare cases, complications can occur, especially diseases of the nervous system (Guillain-Barré syndrome).

Since the minimal infectious dose of Campylobacter jejuni is relatively low, even small numbers of germs can cause campylobacteriosis. It is not necessary for these germs to multiply in the food. Generally, they do not reproduce in the food, but they survive well at refrigerator temperatures and under protective atmospheres.

Main causes of contamination or illness

• insufficient heating of raw meat
• consumption of raw milk
• poor slaughter hygiene and contamination of animal raw materials (especially poultry meat)
• hygiene errors during production
• cross-contamination

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?

In general, 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 foods, it is important to ensure that this temperature-time combination is reached at the core of the product to safely kill the bacteria.

Further information

• 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 Verlag), 1st edition 2013
• Food Microbiology, J. Krämer and A. Prange, 7th edition 2017
• Microorganisms in Foods, H. Keweloh, 2nd edition 2008
• Handbook of Food Hygiene, K. Fehlhaber/J. Kleer/F. Kley (Behrs Verlag), 1st edition 2007
• Information Leaflet "Safely Catered - Particularly Vulnerable Groups in Community Facilities", Federal Institute for Risk Assessment, Berlin 2017

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Profile of "sulfite-reducing Clostridia" and "Clostridium perfringens"

General Information

Clostridia are capable of forming heat-resistant forms, known as spores. These are very heat stable and can survive heating steps. Furthermore, these bacteria can multiply under the exclusion of oxygen (strict anaerobes) and some strains can produce very dangerous toxins.

Origin

These bacteria and their spores are primarily found in soil, water, and also in the intestinal tract of humans and animals. Due to their widespread distribution, both plant and animal foods can be contaminated with these bacteria.

Importance

Many representatives of the group of sulfite-reducing Clostridia play a role as spoilage agents in foods. Also, pathogens like Clostridium perfringens and Clostridium botulinum are found in this group of bacteria.

Clostridium perfringens is significant as a cause of group illnesses in the restaurant and communal catering industries. Surviving spores germinate in the food after the cooking process and subsequently multiply if insufficiently cooled. Their toxins are triggers of food poisoning.

To prevent excessive bacterial counts, it is important to ensure that the critical temperature range between 10 °C – 65 °C is passed through as quickly as possible (max. 3 hours). Frequently affected foods include, for example, larger pieces of meat, soups or sauces in larger containers, vacuum-packed fish products and other vacuum-packed foods, cooked sausages, and improperly sterilized canned goods. Similar applies for Clostridium botulinum, which can form very dangerous toxins (neurotoxins) that cause correspondingly severe to fatal diseases.

Important Causes of Elevated Clostridia Counts

• insufficient heating or sterilization of food, or temperatures that are too low when keeping warm (warming temperatures of, for example, at least +60 °C)
• inadequate curing or smoking, e.g., of ham or fish products
• insufficient cooling or too long storage duration
• use of contaminated raw materials
• too long of a cooling phase. The critical temperature range between 10 °C and 65 °C must be passed through as quickly as possible (usually max. 3 hours)

Growth Conditions

• Temperature: Growth at 12 – 50 °C
• pH Value: Growth at 5.0 – 8.0
• aw Value: Growth up to min. 0.94
• Oxygen Requirement: strictly anaerobic

At What Temperatures Do These Microorganisms Die?

In general, 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 foods, it is important to ensure that this temperature-time combination is achieved at the core of the product to safely kill the bacteria.

The C. perfringens enterotoxin is relatively heat-sensitive, with its biological activity destroyed at 60 °C within 5 minutes.

Further Information and Literature

• www.bfr.bund.de: under "Food Safety"
• www.lgl.bayern.de: under "Food" and then "Hygiene"
• Food Microbiology, J. Krämer and A. Prange, 7th Edition 2017
• Microorganisms in Foods, H. Keweloh, 2nd Edition 2008
• Handbook of Food Hygiene, K. Fehlhaber/J. Kleer/F. Kley (Behrs Verlag), 1st Edition 2007
• Pathogenic Microorganisms: Clostridium perfringens, U. Messelhäußer (Behrs Verlag), 1st Edition 2013
• Leaflet "Safely catered - Particularly vulnerable groups in community facilities", Federal Institute for Risk Assessment, Berlin 2017

Profile on “STEC / VTEC / EHEC”

General Information and Origin

Some strains of Escherichia coli, such as STEC (Shiga toxin-producing Escherichia coli), VTEC (Verotoxin-producing Escherichia coli), or EHEC (Enterohaemorrhagic Escherichia coli), can cause severe foodborne illnesses. In addition to the classic gastrointestinal symptoms of food infections and intoxications (vomiting, diarrhea, fever, …), diseases caused by EHEC strains can lead to HUS syndrome (hemolytic-uremic syndrome) resulting in kidney failure and death.

These dangerous bacteria often occur in the intestines of ruminants (especially cattle, but also, for example, sheep and goats). They can be transmitted to humans through food, as well as through direct contact, for example, in petting zoos.

Significance

The presence of these pathogenic Escherichia coli strains in ready-to-eat foods is undesirable and considered a potential health hazard. Since these infections can sometimes have severe, life-threatening consequences, including death, these pathogens are feared in food. Appropriate measures must be taken when viable STEC/VTEC is detected in ready-to-eat foods. Often, the cause of contamination with these microorganisms is fecal contamination, but due to their longer survival rate in the environment (e.g., in soil), different contamination causes must be considered situationally (see the paragraph below). In addition to raw animal products, these bacteria are also regularly detectable in raw plant foods. Affected foods include raw milk, raw beef, and raw milk cheese, as well as ready-to-eat sprouts and various mixed and leafy salads, and freshly squeezed fruit juices.

Important Causes for Elevated Bacterial Counts

• Fecal or cross-contamination during the slaughtering process
• Contamination of raw animal products, e.g., raw milk and plant-based foods
• Use of contaminated raw materials, e.g., in the production of raw milk soft cheese or mixed, ready-to-eat salads
• Hygiene errors: insufficient separation between raw and processed foods
• Lack of personal hygiene in carriers

Growth Conditions

• Temperature: Growth at 8 - 48 °C
• pH value: Growth to min. 4.0
• aw value: Growth to min. 0.95
• Oxygen requirement: facultatively anaerobic

At what temperatures do these microorganisms die?

In general, it can be assumed that these bacteria are killed at a heating temperature of +72 °C for at least two minutes or in an equally effective process. In food, it must 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.lgl.bayern.de: under „Food“ and then “Hygiene”
• Food Microbiology, J. Krämer and A. Prange, 7th Edition 2017
• Microorganisms in Food, H. Keweloh, 2nd Edition 2008
• Leaflet “Safely Catered – Particularly Sensitive Groups in Community Facilities”, Federal Institute for Risk Assessment, Berlin 2017