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Journal of Clinical Microbiology, August 2005, p. 4277-4279, Vol. 43, No. 8
0095-1137/05/$08.00+0 doi:10.1128/JCM.43.8.4277-4279.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Fatal Family Outbreak of Bacillus cereus-Associated Food Poisoning
Katelijne Dierick,1*
Els Van Coillie,2
Izabela Swiecicka,3
Geert Meyfroidt,4
Hugo Devlieger,5
Agnes Meulemans,6
Guy Hoedemaekers,7
Ludo Fourie,8
Marc Heyndrickx,2 and
Jacques Mahillon9
Institute of Public HealthFood Section, 1050 Brussels, Belgium,1
Ministry of the Flemish Community, Center for Agricultural ResearchDepartment Animal Product Quality, 9090 Melle, Belgium,2
Department of Microbiology, Institute of Biology, University of Bialystok, 15-950 Bialystok, Poland,3
Department of Intensive Care Medicine,4
Department of Paediatrics,5
Department of Emergency Medicine, University Hospital Gasthuisberg, 3000 Leuven, Belgium,6
Department of Paediatrics, Ziekenhuis Maas en Kempen, Maaseik, Belgium,7
Federal Agency for the Safety of the Food Chain, Brussels, Belgium,8
Laboratory of Food and Environmental Microbiology, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium9
Received 23 November 2004/
Returned for modification 6 December 2004/
Accepted 9 April 2005

ABSTRACT
Bacillus cereus is a well-known cause of food-borne illness,
but infection with this organism is not commonly reported because
of its usually mild symptoms. A fatal case due to liver failure
after the consumption of pasta salad is described and demonstrates
the possible severity of the emetic syndrome.

CASE REPORT
In August 2003, five children of a family became sick after
eating pasta salad. The pasta salad was prepared on a Friday
and taken to a picnic on the following Saturday; the remainders
had been stored in the fridge until the following Monday evening,
when they were served for supper to the children. Because the
pasta salad had an unusual smell, three children (B14, G10,
and G9) ate only a small quantity. At 6 h after the meal the
youngest girl (G7), 7 years old, started vomiting. She complained
of respiratory distress and was taken to the emergency department
of a local hospital. Upon arrival, her brothers and sisters
started vomiting as well. Because the clinical condition of
two children (G7 and B9) deteriorated rapidly, they were intubated
and mechanically ventilated. All children were transported to
the University Hospital in Leuven. During transfer, G7 had severe
pulmonary hemorrhage and needed continuous resuscitation. Upon
arrival she was moribund with coma, diffuse bleeding, and severe
muscle cramps. She died within 20 min, at 13 h after the meal.
On autopsy
Bacillus cereus was detected in her gut content but
also in the spleen, probably by postmortem translocation of
the bacterium. A postmortem liver biopsy showed microvascular
and extensive coagulation necrosis. Her initial laboratory values
showed severe metabolic acidosis and liver failure. All four
other children were affected, although to different degrees
(Table
1). The 9-year-old boy (B9) was transferred to the pediatric
intensive care unit, where mechanical ventilation and invasive
hemodynamic monitoring were continued. After fluid resuscitation,
his blood lactate levels gradually went down. Basic treatment
for liver failure consisted of vitamin K supplementation, oral
and rectal lactulose, oral neomycin, and high-dose acetylcysteine.
At 24 h after the start of the treatment his aspartate transaminase
and alanine transaminase levels peaked at 12,254 U/liter and
8,656 U/liter, respectively; his prothrombin time went down
to 21.5%. Thereafter, the hepatic function recovered. He gradually
recovered consciousness, and he was successfully extubated.
Two sisters (G9 and G10) were treated with fluid resuscitation
and bicarbonate substitution. Both gradually recovered. The
14-year-old brother (B14) was kept under observation. Subsequent
blood samples showed no deterioration of hepatic function. The
surviving children could leave the hospital within 8 days.
In six food samples and the vomit of the deceased girl
B. cereus was detected. The samples were not heat treated before analysis.
After 24 h of incubation, the colonies were pink (mannitol negative)
with a precipitation zone (lecithinase positive) on MYP agar
(Oxoid Ltd., Basingstoke, England), beta-hemolytic on Columbia
agar (Oxoid), and positive in motility agar. Gram staining on
Columbia agar-grown colonies showed gram-positive rods with
nondeforming subterminal spores. The highest
B. cereus count
(10
7 to 10
8 CFU/g) was found in the pasta salad, the lowest
count in the vomit (2.0
x 10
2 CFU/g). From each positive sample,
three (or four) isolates were phenotypically confirmed as
B. cereus by use of the API 50 gallery. Further characterization
of the 22 isolates obtained consisted of repetitive sequence-based
PCR (rep-PCR) (
6), pulsed-field gel electrophoresis (PFGE) of
genomic DNA (
5), and PCR analysis of a marker for emetic toxin
(
1). Rep-PCR has been shown before to be useful for outbreak
investigation (
8).
The typing of the isolates was focused on the food and vomit isolates, because the postmortem spleen isolate was not available at that moment. With rep-PCR these isolates could be divided into four groups representing rep types 1 to 4 (Fig. 1); all isolates obtained from the vomit, together with one isolate obtained from the pasta salad and one from the pasta bowl, were clustered within rep type 1. Rep type 4 consisted of 11 isolates, obtained from the pasta salad but also from another type of boiled pasta, chocolate milk, and semiskimmed milk, which indicates cross-contamination during handling of the food. PFGE revealed four distinct restriction patterns (PFGE types A to D) (Fig. 1 and 2). The majority of the isolates (n = 16) were classified as PFGE type C, which included isolates from the boiled pasta, the pasta salad, chocolate milk, vomit, semiskimmed milk, and the bowl. All these PFGE type C isolates corresponded to rep type 1 or 4 (Fig. 1), indicating a high discriminatory potential of rep-PCR. The above-described data indicate that more than one strain was present in this intoxication case, and they illustrate the importance of obtaining multiple isolates from even one food sample (Fig. 1). Detection of B. cereus emetic and enterotoxin production was performed with cytotoxicity assays (2, 4). Both tested isolates of rep type 1 (vomit and pasta salad) and the three tested isolates from rep type 4 produced the emetic toxin and were also positive in the emetic toxin-specific PCR assay (Fig. 1).
Although
Bacillus cereus is a well-known cause of food-borne
illness it is not commonly reported because of its usually mild
symptoms. It can cause two types of food poisoning known as
the emetic and the diarrheal types. The emetic type is caused
by a heat-stable toxin, named cereulide, preformed in the food.
Only one fatal case has been reported up to now (
9). The present
results provided evidence for
B. cereus food poisoning of five
children of one Belgian family. The clinical data and the rapid
onset of symptoms, together with the microbiological and molecular
study, pointed to
B. cereus as the causative agent. It has been
demonstrated that
B. cereus from the pasta salad, the vomit
of the deceased girl, and the pasta bowl produced identical
patterns on the basis of both analyses (rep type 1 and PFGE
type C).
Although the presence of cereulide in the pasta salad was not directly demonstrated, its production at a high level was indirectly proven in the cytotoxicity test of the isolates. These results were confirmed by PCR (1), which amplifies a DNA fragment whose presence is specific for cereulide-producing strains. All the isolates classified as PFGE type C and rep type 1 reacted positively with these primers, indicating the presence of cereulide-related genes. Also, the rest of the isolates of PFGE type C but pertaining to rep type 4 harbored the cereulide genetic determinants. Thus, although no isolate of rep type 4 was detected in the vomit, these isolates could also have produced the toxin in the pasta salad.
The present case illustrates the possible severity of the emetic syndrome and the importance of adequate refrigeration of prepared food. Because the emetic toxin is preformed in the food and not inactivated by heat treatment (7) it is important to prevent growth and the production of cereulide during storage. Some B. cereus strains are known to be psychrotrophic and to have the highest emetic toxin production between 12- and 15°C (3). In this case, the temperature of the fridge where the pasta salad was stored was 14°C. This allowed B. cereus to grow to a count of more than 108 CFU/g in 3 days with a probably very high toxin production that may explain the fatal outcome.

FOOTNOTES
* Corresponding author. Mailing address: Institute of Public Health, 14 Juliette Wijtsman Str., B-1050 Brussels, Belgium. Phone: 00 32 2 642 51 53. Fax: 00 32 2 642 53 27. E-mail:
Katelijne.Dierick{at}iph.fgov.be.


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Journal of Clinical Microbiology, August 2005, p. 4277-4279, Vol. 43, No. 8
0095-1137/05/$08.00+0 doi:10.1128/JCM.43.8.4277-4279.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
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