A cluster of three cases of food-borne botulism due to Clostridium baratii type F occurred in France in August 2015.
Foodborne botulism is primarily caused by ingestion of food contaminated by C. botulinum. Botulism caused by C. baratii is rare.
The investigation identified the ground meat used to prepare the sauce as the most probable vehicle of C. baratii contamination. However, the ultimate source and mode of contamination of the meat remain unknown. No further case was identified in France during the shelf-life of the contaminated meat despite the wide distribution of the product, and the investigation of the producer’s stored samples was negative.
No toxin was found in frozen and defrosted ground meat but the sauce eaten by the patients was not tested. Based on the restaurant inspection results (no temperature monitoring of stored preparations) and given the known conditions of toxin production, we can hypothesise that the botulinum toxin was produced during the sauce cooking process or storage. Indeed, preparations of a large volume of meat sauce by boiling for more than ten minutes and storage at room temperature for several hours are favourable conditions including anaerobiosis and substrate requirement for Clostridium growth and toxin production.