Bacillus cereus contamination can lead to serious consequences…

By Jennifer Johnson

A couple of recent incidents have brought Bacillus cereus back into focus. In the UK for example, liquid baby formula contaminated with the bacteria killed one premature baby and was responsible for sickening 14 others in six different hospitals. Then, in China, 139 people become sick after consuming fermented
black beans
(douchi) in Yunan. After studies were done on vomit samples and the unprepared douchi, three Bacillus cereus strains were isolated.

Bacillus cereus is an aerobic and facultatively anaerobic, motile, spore-forming gram-positive rod.  B. cereus exists in two forms: spores and vegetative cells.  Because B. cereus is found in soil, so raw plant foods such as rice, potatoes, peas, beans and spices, are common sources of the organism. The presence of the organism in processed foods results from the contamination of the raw materials and the subsequent resistance of the spores to thermal and other manufacturing processes. During food’s cooling process, spores may germinate, enabling B. cereus to multiply and produce high levels of the emetic toxin cereulide.

After consumption of contaminated foods, B. cereus causes two types of gastroenteritis. One is an emetic syndrome with a relatively short incubation period of 1-6 hours that results in nausea and vomiting. The other is a diarrheal syndrome with an incubation period of 6-24 hours causing watery diarrhea, abdominal cramps, and pain.

This quick onset of symptoms can pose a serious problem for passengers on an
international flight for example, where many people can become sick in a short period of time. While foodborne illness associated with air travel is quite uncommon, foodborne outbreaks have been recorded by the airline industry as a result of improper testing or handling of food. When this does occur, it can have serious implications for passengers and crew members and means quality, safe, in-flight catering must rely on high standards of food preparation and storage; this applies at the airport kitchens (or at subcontractors’ facilities) and on the aircraft.

Bacillus cereus has also been recognized as a cause of potentially fatal systemic infections outside the GI tract, particularly in high-risk patients, such as infants, immune-compromised individuals, and chronically debilitated or elderly patients.  These infections include bacteremia, septicemia, meningitis, cerebral abscess, pneumonia, and endocarditis.

The risk of illness after ingestion of vegetative B. cereus cells is influenced by the strain, composition of the food, the liquid nature of the food and the age of the individual. Young children are particularly susceptible and may be more severely affected by a B. cereus contamination resulting in severe complications and even death. Because liquid foods, such as infant formula, are transported faster to the small intestine they are protected from the influence of gastric conditions, providing more opportunity for the survival of the pathogen.

BioLumix B. cereus Vial:

Detecting B. cereus as quickly and easily as possible is of paramount importance when corrective action(s) can minimize public exposure. BioLumix has an assay that detects B. cereus in 24 hours. The B. cereus vial’s sensor detects production of CO2. The disposable vial contains a transparent solid sensor located at the bottom which changes its optical properties whenever CO2 diffuses into it. Only gases can penetrate the sensor; blocking liquids, microorganisms, and particulate matter. Consequently, the optical readings are not masked by the sample. CO2 generated by B. cereus metabolism in the liquid medium placed above the sensor, diffuses into the sensor and interacts with an indicator reagent to provide an indication of the presence of the carbon dioxide. The medium contains growth promoting ingredients and inhibitors to gram-negative and non-Bacillus cereus gram-positive organisms.  The method used is very simple; just pipette the diluted sample into the vial and your results can be obtained in 24 hours or less.

Advantages of BioLumix Vials:

  • Vials can be stored at room temperature
  • Prefilled ready-to-use vials come with a Certificate of Analysis
  • Automated same day test results
  • Vials are available for a variety of tests, each with organism-specific enrichment medium
  • A single organism can be detected in a vial, if capable of growth in the medium
  • Liquid culture from a vial can be used to perform further tests