A cluster of three cases were reported in August 2015 from people who ate at one restaurant.
Clostridium baratii was isolated from stool specimens of the patients by PCR and culture.
It was the second C. baratii type F botulism outbreak in France in less than one year.
Ground meat for sauce
The investigation identified the ground meat used to prepare the sauce as the most probable vehicle of C. baratii contamination.
No toxin was found in frozen and defrosted ground meat but the sauce eaten by the patients was not tested, said the researchers.
“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.”
No neurotoxigenic Clostridium or toxin was identified in food samples collected during the first inspection (one day after the notification of the first two cases).
However, frozen and defrosted ground meat samples were positive for C. Baratii but no toxin was detected.
The Regional Health Agency (ARS) and the French Institute for Public Health Surveillance (InVS) investigated the incident.
One day after the notification of the first two cases (clinical suspicion), the implicated restaurant was inspected by the district food control authority (DDPP). Inspection revealed hygiene deficiencies in food manufacturing and storage.
Samples were collected and sent to the National Reference Center (NRC) for anaerobic bacteria and botulism in Paris. Two days later, although no leftover from the implicated Bolognese sauce was available, a second collection of food samples targeting sauce ingredients was performed.
Distribution since March
One day after the second inspection, the restaurant closed for stock renewal and environmental cleaning.
An investigation of the contaminated meat batch by the Ministry of Agriculture (DGAL) led to a product recall.
Although it had been distributed to different catering facilities since March 2015, no C. baratii-related botulism case had been reported between March and August 2015.
All patients developed quadriplegia and respiratory failure requiring intubation and respiratory assistance between 24 and 48 hours after symptom onset.
Length of hospitalisation varied between 16–38 days but all patients recovered.
The researchers said assumingthis type of botulism is emerging, it needs to be monitored with caution, because investigations of new cases in France and Europe may bring new information about the origin of the contamination by C. baratii.
In Europe, the current botulinum antitoxin (capable of protecting against type A, B, E toxins) is not appropriate in type F botulism, so the replacement with the heptavalent antitoxin could be considered, they added.
Source: Eurosurveillance, Volume 21, Issue 4, 28 January 2016
“A cluster of three cases of botulism due to Clostridium Baratii type F, France, August 2015”
Authors: H Tréhard, I Poujol, C Mazuet, Q Blanc, Y Gillet, F Rossignol, M Popoff, N Jourdan Da Silva