An outbreak of Bacillus cereus implicating a part-time banquet caterer.
OBJECTIVE
In the aftermath of a party, 70% (25 of 36) of attendees had gastroenteritis. The objectives of this study were to identify a risk factor associated with the food during the banquet and to identify measures of control for avoiding this kind of outbreak in the future.


METHODS
A retrospective cohort study was used. We tried to reach by telephone all guests who had attended this banquet. A standardized questionnaire was used to provide information about identification of a risk factor, especially in relation to food.


RESULTS
The cohort study has shown that potato salad served at the party was significantly associated with the disease. The mayonnaise used to prepare the salad was analyzed and Bacillus cereus was isolated (10(3) bacteria per gram).


CONCLUSIONS
Bacillus microorganisms are usually found in decaying organic matter, dust, soil, vegetables and water. The bacteria has a remarkable ability to survive strong environmental stresses. There are strains of B. cereus that can cause food poisoning episodes with infective doses as low as 10(3) to 10(4) bacteria per gram. B. cereus is an infrequently reported cause of foodborne illnesses in Quebec and in North America but this may be due to underreporting of episodes. In this outbreak, bacterial multiplication was facilitated at several points in the interval between the preparation of the meal and the consumption of the banquet by the guests. Because the spores are ubiquitous and resistant to inactivation with most food grade disinfectants, temperature control should be the main focus of B. cereus outbreak prevention.


CONCLUSIONS
The meal was prepared by a restaurateur who was inexperienced in catering services and temperature control in particular when food is served outside the restaurant. This outbreak underscores the importance of maintaining meticulous hygienic procedures in food processing. Restaurateurs who offer catering services should be familiar with the constraints that are specific to this sector of the food industry.
D001409:Bacillus cereus / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology; D015331:Cohort Studies; D004196:Disease Outbreaks / Q000517:prevention & control; D005506:Food Contamination; D005522:Food Services / Q000592:standards*; D005517:Foodborne Diseases / Q000382:microbiology*; D006801:Humans; D011792:Quebec / Q000453:epidemiology; D012147:Restaurants / Q000592:standards; D012499:Sanitation