News
04.11.2024 - Analytics
Bacillus cereus as a cause of foodborne intoxications (1)
Due to a recent fatality, where the cause is currently suspected to be a Bacillus cereus intoxication, we would like to provide you with important information about this bacterial toxin producer below.
General Information:
Bacillus cereus is a rod-shaped, gram-positive bacterium that is widely distributed in the environment and often associated with food poisoning (vomiting and/or diarrhea). It is known for the formation of heat-resistant spores. These spores are heat stable and can partially survive heating steps in the manufacturing process.
Origin:
These bacteria and their spores are widespread in our environment. They can be found in soil, dust, water, animals, and humans. Therefore, contamination of virtually all raw plant and animal foods with this germ is possible.
Significance:
Spores of these bacteria can germinate after a heating step in food and proliferate under insufficient cooling and suitable environmental conditions. To avoid increased germination, it is important to quickly pass through the critical temperature range between 10°C and 60°C after heating. Particular caution is advised when cooling large portions. Foods at risk include cooked rice, pasta, sauces, dairy products, salads/vegetables, and desserts.
These bacteria play a special role as causes of group illnesses in community catering. Therefore, they are of great importance in community catering, gastronomy, and private households.
Primary Reasons for Elevated Germ Counts:
- Too low temperatures during warming (typically, warming temperatures of >+60°C are required)
- Too long cooling phase. The critical temperature range between 10°C and 60°C must be passed as quickly as possible (generally max. 3 hours)
- Insufficient cooling and/or overripening of food (overestimation of shelf life)
- Microbially contaminated raw materials, e.g., herbs, spices, flours...
Growth Conditions:
- Temperature: Growth at 4 - 50°C, toxin production at 37 - 42°C
- pH Value: Growth at 4.3 – 10.5, toxin production up to max. 10.0
- aw Value: Growth up to min. 0.92 – 0.95
- Salt Tolerance: 0.5 – 9 %
- Oxygen Requirement: Facultative anaerobic, preferably aerobic
At What Temperatures Do These Microorganisms Die?
In general, it can be assumed that vegetative bacteria are killed by heating to +72°C for at least two minutes or by an equivalent process. With foods, it should be noted that the temperature-time combination must be achieved in the core of the product to kill the bacteria safely.
However, spores of these bacteria are often present in foods. These are generally highly heat-resistant and can even survive cooking processes.
Examinations for Bacillus cereus:
We offer you quick and reliable examinations for presumptive Bacillus cereus. In addition to ISO procedures, we also regularly apply an accredited rapid method in our laboratory. This takes only 1 day, instead of the examination duration of 2-3 days when applying ISO methods.
Through further molecular biological methods, we can also distinguish between various species within the Bacillus cereus group.
In general, we offer the following rapid methods in our laboratory:
Parameter Examination Duration Examination Principle Accreditation
Salmonella 1 Day RT-PCR Yes
TentaSpeed
Listeria monocytogenes/ 6 Hours RT-PCR No
Listeria spp.
Listeria monocytogenes/ 1 Day RT-PCR Yes
Listeria spp.
Cronobacter spp. 1 Day RT-PCR Yes
STEC/ VTEC 1 Day RT-PCR Yes
Campylobacter spp. 2 Days Cultural Yes
Presumptive Bacillus cereus 1 Day Cultural Yes
Yeasts and Molds 3 Days Cultural Yes
Lactic Acid Bacteria 2 Days Cultural Yes
Pseudomonads 2 Days Cultural Yes
Coagulase-positive
Staphylococci 1 Day Cultural Yes
Legionella 6 Hours RT-PCR No
Identification /
Strain Comparison 2 to 24 Hours Maldi-Tof Yes
Consult our experts on topics related to Bacillus cereus. We provide competent advice and deliver quick and reliable results.
For further inquiries, our customer advisors or Dirk Lorenz are available by phone at 0781/96947-23 or by email at dirk.lorenz@bav-institut.de.