Food Poisoning Caused by Gram-Positive Sporeforming Bacteria
585
and others.
34 Reported outbreaks between 1950 and 1978 have been summarized by Gilbert,
34 and
when plate counts on leftover foods were recorded, they ranged from 10
5 to 9.5 × 10
5 /g, with many
in the 10
7 –10
8 /g range. The first well-studied outbreaks were those investigated by Hauge
46 , which
were traced to vanilla sauce; the counts ranged from 2.5 × 10
7 to 1 × 10
8 /g. From meat loaf involved
in a U.S. outbreak in 1969, 7 × 10
7 /g were found.
81 Serovars found in diarrheal outbreaks include
types 1, 6, 8, 9, 10, and 12. Serovars 1, 8, and 12 have been associated with this as well as with the
emetic syndrome.
34
Emetic Syndrome
This form of B. cereus food poisoning is more severe and acute than the diarrheal syndrome. The
incubation period ranges from 1 to 6 hours, with 2 to 5 hours being most common.
87 Its similarity to the
staphylococcal food-poisoning syndrome has been noted.
34 It is often associated with fried or boiled
rice dishes. In addition to these, pasteurized cream, spaghetti, mashed potatoes, and vegetable sprouts
have been incriminated.
34 Outbreaks have been reported from Great Britain, Canada, Australia, the
Netherlands, Finland, Japan, and the United States. The first U.S. outbreak was reported in 1975, with
mashed potatoes as the vehicle food.
The numbers of organisms necessary to cause this syndrome seem to be higher than those for
the diarrheal syndrome, with numbers as high as 2 × 10
9 /g having been found.
34 B. cereus serovars
associated with the emetic syndrome include 1, 3, 4, 5, 8, 12, and 19.
34
The emetic (vomiting type) toxin has been determined to be cereulide, an ionophoric, water-insoluble
peptide that is closely related to the peptide antibiotic valinomycin.
1 It has a molecular weight of about
1.2 kDa. It induces the formation of vacuoles in HEp-2 cells (see Chapter 12), and neither this activity
nor the emetic is lost after heating for 30 minutes at 121
◦ C.
1,2 The house musk or shrew (Suncus
murinus) has been found to be a suitable experimental animal for the emetic activity.
2
Using 3 B. cereus strains and either tryptic soy or trypticase soy media, cereulide production commenced at the end of the log phase of growth and toxin production was independent of sporulation.
44
The strains produced 80 to 166 µg of cereulide/ml at 21
◦ C in 1 to 3 days during the stationary growth
phase when cell numbers reached 2 × 10
8 to 6 × 10
8 cfu/ml. Production at 40 and below 8
◦ C was
minimal.
44
The emetic toxin strains grow over the range 15–50
◦ C, with an optimum between 35
◦ C and 40
◦ C.
56
Whereas the emetic syndrome is most often associated with rice dishes, growth of the emetic toxin
strains in rice is not favored in general over other B. cereus strains, although higher populations and
more extensive germination have been noted in this product.
56
REFERENCES
1. Agata, N., M. Ohta, M. Mori, and M. Isobe. 1995. A novel dodecadepsipeptide, cereulide, is an emetic toxin of Bacillus
cereus. FEMS Microbiol. Lett. 129:17–20.
2. Agata, N., M. Mori, M. Ohta, S. Suwan, I. Ohtani, and M. Isobe. 1994. A novel dodecadepsipeptide, cereulide, isolated
from Bacillus cereus causes vacuole formation in HEp-2 cells. FEMS Microbiol. Lett. 121:31–34.
3. Alderton, G., K.A. Ito, and J.K. Chen. 1976. Chemical manipulation of the heat resistance of Clostridium botulinum
spores. Appl. Environ. Microbiol. 31:492–498.
4. Alderton, G., and N. Snell. 1969. Bacterial spores: Chemical sensitization to heat. Science. 163:1212–1213.
5. Anastasio, K.L., J.A. Soucheck, and H. Sugiyama. 1971. Boticinogeny and actions of the bacteriocin. J. Bacteriol.
107:143–149.
585
and others.
34 Reported outbreaks between 1950 and 1978 have been summarized by Gilbert,
34 and
when plate counts on leftover foods were recorded, they ranged from 10
5 to 9.5 × 10
5 /g, with many
in the 10
7 –10
8 /g range. The first well-studied outbreaks were those investigated by Hauge
46 , which
were traced to vanilla sauce; the counts ranged from 2.5 × 10
7 to 1 × 10
8 /g. From meat loaf involved
in a U.S. outbreak in 1969, 7 × 10
7 /g were found.
81 Serovars found in diarrheal outbreaks include
types 1, 6, 8, 9, 10, and 12. Serovars 1, 8, and 12 have been associated with this as well as with the
emetic syndrome.
34
Emetic Syndrome
This form of B. cereus food poisoning is more severe and acute than the diarrheal syndrome. The
incubation period ranges from 1 to 6 hours, with 2 to 5 hours being most common.
87 Its similarity to the
staphylococcal food-poisoning syndrome has been noted.
34 It is often associated with fried or boiled
rice dishes. In addition to these, pasteurized cream, spaghetti, mashed potatoes, and vegetable sprouts
have been incriminated.
34 Outbreaks have been reported from Great Britain, Canada, Australia, the
Netherlands, Finland, Japan, and the United States. The first U.S. outbreak was reported in 1975, with
mashed potatoes as the vehicle food.
The numbers of organisms necessary to cause this syndrome seem to be higher than those for
the diarrheal syndrome, with numbers as high as 2 × 10
9 /g having been found.
34 B. cereus serovars
associated with the emetic syndrome include 1, 3, 4, 5, 8, 12, and 19.
34
The emetic (vomiting type) toxin has been determined to be cereulide, an ionophoric, water-insoluble
peptide that is closely related to the peptide antibiotic valinomycin.
1 It has a molecular weight of about
1.2 kDa. It induces the formation of vacuoles in HEp-2 cells (see Chapter 12), and neither this activity
nor the emetic is lost after heating for 30 minutes at 121
◦ C.
1,2 The house musk or shrew (Suncus
murinus) has been found to be a suitable experimental animal for the emetic activity.
2
Using 3 B. cereus strains and either tryptic soy or trypticase soy media, cereulide production commenced at the end of the log phase of growth and toxin production was independent of sporulation.
44
The strains produced 80 to 166 µg of cereulide/ml at 21
◦ C in 1 to 3 days during the stationary growth
phase when cell numbers reached 2 × 10
8 to 6 × 10
8 cfu/ml. Production at 40 and below 8
◦ C was
minimal.
44
The emetic toxin strains grow over the range 15–50
◦ C, with an optimum between 35
◦ C and 40
◦ C.
56
Whereas the emetic syndrome is most often associated with rice dishes, growth of the emetic toxin
strains in rice is not favored in general over other B. cereus strains, although higher populations and
more extensive germination have been noted in this product.
56
REFERENCES
1. Agata, N., M. Ohta, M. Mori, and M. Isobe. 1995. A novel dodecadepsipeptide, cereulide, is an emetic toxin of Bacillus
cereus. FEMS Microbiol. Lett. 129:17–20.
2. Agata, N., M. Mori, M. Ohta, S. Suwan, I. Ohtani, and M. Isobe. 1994. A novel dodecadepsipeptide, cereulide, isolated
from Bacillus cereus causes vacuole formation in HEp-2 cells. FEMS Microbiol. Lett. 121:31–34.
3. Alderton, G., K.A. Ito, and J.K. Chen. 1976. Chemical manipulation of the heat resistance of Clostridium botulinum
spores. Appl. Environ. Microbiol. 31:492–498.
4. Alderton, G., and N. Snell. 1969. Bacterial spores: Chemical sensitization to heat. Science. 163:1212–1213.
5. Anastasio, K.L., J.A. Soucheck, and H. Sugiyama. 1971. Boticinogeny and actions of the bacteriocin. J. Bacteriol.
107:143–149.