Bacillus cereus in food: when it multiplies, the bacterium can produce a toxin Following recall of infant formula, the BfRshort forGerman Federal Institute for Risk Assessment compiles basic information

According to the information provided, the recall was carried out because one of the ingredients supplied to the infant formula manufacturer may contain the toxin cereulide. This toxin can be produced by certain bacteria of the Bacillus cereus group, known as "emetic Bacillus cereus". The bacteria can form very stable persistent forms, known as spores. These are prevalent in food and are not a problem at low concentrations. However, if the spores germinate and the bacteria multiply, it is possible that cereulide is formed in the food. This requires suitable conditions in the food, particularly with regard to moisture content, pH value, salt content, available nutrients, competing microorganisms and storage temperature.

Cereulide is not inactivated by heating, so boiling food does not eliminate the toxin. If cereulide is taken up with food, it can cause nausea and vomiting within 0.5 to 6 hours. These symptoms give rise to the term "emetic", which means "causing nausea". The symptoms are usually self-limiting within 24 hours. However, in  rare cases of severe poisoning due to high concentrations of cereulide, organ damage can occur, particularly affecting the liver and kidneys. In the past, this has led to fatal illnesses in isolated cases.

The BfRshort forGerman Federal Institute for Risk Assessment is not aware of any reports to date in which cereulide itself has been detected in infant milk powder. However, emetic Bacillus cereus have been found in infant milk powder in the past. Due to the low water content, the pathogen cannot multiply in the undissolved powder and therefore cereulide cannot be formed. However, if this powder is dissolved and stored at room temperature for several hours, the bacteria can multiply and cereulide can be formed. It is therefore important that powdered infant formula is always prepared immediately before consumption.