7.2 Bacillus cereus and other Bacillus Species
7.2.1 Introduction
An early report associating food poisoning withBacillusspp. was made
in 1906 when Lubenau described an outbreak in a sanatorium where 300
inmates and staff developed symptoms of profuse diarrhoea, stomach
cramps and vomiting. A spore forming bacillus was isolated from
meatballs from the incriminated meal. Although Lubenau named the
organism Bacillus peptonificans, the properties he described resemble
those ofB. cereus. Subsequently, aerobic spore formers were implicated
in a number of outbreaks in Europe and between 1936 and 1943 they
were suspected of causing 117 of 367 cases investigated by the Stockholm
Board of Health.
Bacillus cereuswas not conclusively established as a cause of food
poisoning until 1950, after the taxonomy of the genus had been clarified.
Hauge described four outbreaks in Norway involving 600 people. The
food vehicle was a vanilla sauce which had been prepared a day in
advance and stored at room temperature before serving. Samples of the
sauce later tested contained from 2.5 107 to 1.1 108 B.cereusml^1.
This classic report and many of the early ones from Europe described an
illness in which diarrhoea was the predominant symptom. It is now
known thatB. cereusis responsible for two distinct types of foodborne
illness: a relatively late-onset, ‘diarrhoeal syndrome’ and a rapid-onset,
‘emetic syndrome’, first described in 1971 in the UK.
Since 1975 a number of otherBacillusspecies have been associated
with foodborne illness. In these episodes, tests have failed to find known
pathogens but food remnants and/or clinical specimens have yielded
high numbers ofBacillusspp. Far less common than outbreaks featuring
B. cereus, they usually involve very closely related species such as
B. licheniformisandB. pumilisorB. subtilis. B. thuringiensishas also
been reported as causing an outbreak in Canada.
Overall, the reported number of cases of foodborne illness due to
Bacillusspp. in the UK is much lower than those forSalmonella. Since
1992 there have been up to 10 outbreaks each year involving a total of 67
cases. Such statistics though, are likely to underestimate the true level far
more than those forSalmonellasince the data come only from outbreaks
and there is no estimate of sporadic cases. In some Northern European
countries however the organism appears to have far greater importance.
It accounted for 33% of total bacterial food poisoning cases in Norway
between 1988 and 1993, 47% in Iceland (1985–1992), 22% in Finland
(1992) and 8.5% in the Netherlands (1991). In Denmark, England
and Wales, Japan, the USA and Canada the figure ranges between 0.7
and 5.0%.
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