Food Poisoning Caused by Gram-Positive Sporeforming Bacteria
583
This syndrome is diagnosed by demonstrating botulinal toxins in infant stools and by the use of the
mouse lethality test. Because Clostridium difficile produces mouse-lethal toxins in the intestinal tract
of infants, it is necessary to differentiate between these toxins and that of C. botulinum.
35
Infants get viable spores from infant foods and possibly from their environment. Vehicle foods are
those that do not undergo heat processing to destroy endospores; the two most common products are
syrup and honey. Of 90 samples of honey examined, 9 contained viable spores. Six of these had been
fed to babies who developed infant botulism.
83 Of the nine, seven were type B and two were type A.
Of 910 infant foods from 10 product classes, only 2 classes were positive for spores: honey and corn
syrup.
59 Of 100 honey samples, 2 contained type A, and 8 of 40 corn syrup samples yielded type B.
In Canada, only 1 of 150 samples of honey contained viable botulinal spores (type A), 1 of 40 dry
cereal samples (type B), whereas 43 syrup samples were negative.
56 Reported cases in the United
States through 1997 revealed 62 cases for 1982, which occurred among infants aged 2–48 weeks, and
involved type A and B toxins equally. The first two cases reported in Rome, Italy, were caused by
type E toxin, which was produced by Clostridium butyricum.
21 The first reported infant case caused
by type B in Japan occurred in 1995, and the toxin was found to possess a lower toxicity and possibly
a lower binding capacity than the adult form.
62
Animal models for the study of this syndrome consist of 8- to 11-day-old mice
118 and 7- to 13-dayold rats.
85 In the mouse model, botulinal toxin was found in the lumen of the large intestine, and it
was not associated with the ileum. (The sensitivity of these animal models is noted in Chapter 12.)
BACILLUS CEREUS GASTROENTERITIS
Bacillus cereus is an aerobic, spore-forming rod normally present in soil, dust, and water. It has been
associated with food poisoning in Europe since at least 1906. Among the first to report this syndrome
with precision was Plazikowski. His findings were confirmed by several other European workers in
the early 1950s. The first documented outbreak in the United States occurred in 1969, and the first in
Great Britain occurred in 1971.
Low numbers of this bacterial species can be found in a number of food products, including fresh
and processed foods. In a study of raw meats, meat products, and product additives, B. cereus was
found in 6.6% of 534, 18.3% of 820, and 39.1% of 609 samples, respectively,
61 with levels of 10
2 –
10
4 /g. It is unclear if any were enterotoxigenic. Enterotoxigenic strains were recovered from a variety
of foods in another study, with 85% of 83 strains from raw milk being positive for the diarrheagenic
toxin.
43 Other enterotoxin-producing species are listed below.
In addition to B. cereus, B. mycoides strains from milk have been shown to produce diarrheagenic
enterotoxin in nine days at temperatures between 6
◦ C and 21
◦ C.
43 Varying numbers of isolates of the
following species were found also to be enterotoxin producers: P. circulans, B. lentus, B. thuringiensis,
B. pumilus, P. polymyxa, B. carotarum, and B. pasterurii.
43 B. thuringiensis has been isolated from
foods, and it apparently produces a Vero-cell active toxin.
23
This bacterium has a minimum growth temperature around 4–5
◦ C, with a maximum around 48–
50
◦ C. Growth has been demonstrated over the pH range 4.9–9.3.
40 Its spores possess a resistance to
heat typical of other mesophiles.
B. cereus Toxins
This bacterium produces a wide variety of extracellular toxins and enzymes, including lecithinase, proteases, β-lactamase, sphingomyelinase, cereolysin (mouse lethal toxin, hemolysin I), and
583
This syndrome is diagnosed by demonstrating botulinal toxins in infant stools and by the use of the
mouse lethality test. Because Clostridium difficile produces mouse-lethal toxins in the intestinal tract
of infants, it is necessary to differentiate between these toxins and that of C. botulinum.
35
Infants get viable spores from infant foods and possibly from their environment. Vehicle foods are
those that do not undergo heat processing to destroy endospores; the two most common products are
syrup and honey. Of 90 samples of honey examined, 9 contained viable spores. Six of these had been
fed to babies who developed infant botulism.
83 Of the nine, seven were type B and two were type A.
Of 910 infant foods from 10 product classes, only 2 classes were positive for spores: honey and corn
syrup.
59 Of 100 honey samples, 2 contained type A, and 8 of 40 corn syrup samples yielded type B.
In Canada, only 1 of 150 samples of honey contained viable botulinal spores (type A), 1 of 40 dry
cereal samples (type B), whereas 43 syrup samples were negative.
56 Reported cases in the United
States through 1997 revealed 62 cases for 1982, which occurred among infants aged 2–48 weeks, and
involved type A and B toxins equally. The first two cases reported in Rome, Italy, were caused by
type E toxin, which was produced by Clostridium butyricum.
21 The first reported infant case caused
by type B in Japan occurred in 1995, and the toxin was found to possess a lower toxicity and possibly
a lower binding capacity than the adult form.
62
Animal models for the study of this syndrome consist of 8- to 11-day-old mice
118 and 7- to 13-dayold rats.
85 In the mouse model, botulinal toxin was found in the lumen of the large intestine, and it
was not associated with the ileum. (The sensitivity of these animal models is noted in Chapter 12.)
BACILLUS CEREUS GASTROENTERITIS
Bacillus cereus is an aerobic, spore-forming rod normally present in soil, dust, and water. It has been
associated with food poisoning in Europe since at least 1906. Among the first to report this syndrome
with precision was Plazikowski. His findings were confirmed by several other European workers in
the early 1950s. The first documented outbreak in the United States occurred in 1969, and the first in
Great Britain occurred in 1971.
Low numbers of this bacterial species can be found in a number of food products, including fresh
and processed foods. In a study of raw meats, meat products, and product additives, B. cereus was
found in 6.6% of 534, 18.3% of 820, and 39.1% of 609 samples, respectively,
61 with levels of 10
2 –
10
4 /g. It is unclear if any were enterotoxigenic. Enterotoxigenic strains were recovered from a variety
of foods in another study, with 85% of 83 strains from raw milk being positive for the diarrheagenic
toxin.
43 Other enterotoxin-producing species are listed below.
In addition to B. cereus, B. mycoides strains from milk have been shown to produce diarrheagenic
enterotoxin in nine days at temperatures between 6
◦ C and 21
◦ C.
43 Varying numbers of isolates of the
following species were found also to be enterotoxin producers: P. circulans, B. lentus, B. thuringiensis,
B. pumilus, P. polymyxa, B. carotarum, and B. pasterurii.
43 B. thuringiensis has been isolated from
foods, and it apparently produces a Vero-cell active toxin.
23
This bacterium has a minimum growth temperature around 4–5
◦ C, with a maximum around 48–
50
◦ C. Growth has been demonstrated over the pH range 4.9–9.3.
40 Its spores possess a resistance to
heat typical of other mesophiles.
B. cereus Toxins
This bacterium produces a wide variety of extracellular toxins and enzymes, including lecithinase, proteases, β-lactamase, sphingomyelinase, cereolysin (mouse lethal toxin, hemolysin I), and