668 Modern Food Microbiology
of nonenterocolitica species, including Y. intermedia and Y. kristensenii, were positive for ST in two
other studies.
129,136 Y. bercovieri produces a heatstable enterotoxin (YbST), and detectable levels are
produced at 4
◦ C after 144–168 hours.
122
Although pathogenic strains of Y. enterocolitica produce ST, it appears that this agent is not critical
to virulence. Some evidence for the lack of importance of ST was provided by Schiemann,
112 who
demonstrated positive HeLa-cell and Sereny-test responses, with a 0:3 strain that did not produce
enterotoxin. On the other hand, each of 49 isolates belonging to serovar 0:3 and the other four virulent
serovars produced ST.
88 In addition to the diminished role of ST in Y. enterocolitica virulence, some
other properties now seem less important.
22,81 The Yop virulon is the most significant virulence factor
for yersiniae, and it along with some of the more recent findings on the pathogenesis of these organisms
is discussed in Chapter 22.
Incidence of Y. enterocolitica in Foods
This organism has been isolated from cakes, vacuum-packaged meats, seafood, vegetables, milk,
and other food products. It has been isolated also from beef, lamb, and pork.
77 Of all sources, swine
appears to be the major source of strains pathogenic for humans. More specifically, pig tonsils have
been found to be the primary sources of contamination of liver, heart, and kidneys.
43 The incidence
and growth of Y. enterocolitica in milk are presented in Chapter 7, and for meats in Chapter 4.
Gastroenteritis Syndrome and Incidence
In addition to gastroenteritis, this organism has been associated with human pseudoappendicitis,
mesenteric lymphadenitis, terminal ileitis, reactive arthritis, peritonitis, colon and neck abscesses,
cholecystis, and erythema nodosum. It has been recovered from urine, blood, cerebrospinal fluid, and
the eyes of infected individuals. It is, of course, recovered from the stools of gastroenteritis victims.
Only the gastroenteritis syndrome is addressed below.
There is a seasonal incidence associated with this syndrome, with the fewest outbreaks occurring
during the spring and the greatest number in October and November. The incidence is highest in the
very young and the old. In an outbreak studied by Gutman et al.,
49 the symptoms (and percentage
complaining of them) were fever (87), diarrhea (69), severe abdominal pain (62), vomiting (56),
pharyngitis (31), and headache (18). The outbreak led to two appendectomies and two deaths.
Milk (raw, improperly pasteurized, or recontaminated) is a common vehicle food. The first documented outbreak in the United States occurred in 1976 in New York State, with serovar 0:8 as the
responsible strain, and chocolate milk prepared by adding chocolate syrup to previously pasteurized
milk was the vehicle food.
12 An outbreak of serotype 0:3 among 15 children occurred in Georgia in
1988–1989; the vehicle food was raw chitterlings.
30
Symptoms of the gastroenteritis syndrome develop several days following ingestion of contaminated
foods and are characterized by abdominal pain and diarrhea. Children appear to be more susceptible
than adults, and the organisms may be present in stools for up to 40 days following illness.
4 A variety
of systemic involvements may occur as a consequence of the gastroenteritis syndrome.
CAMPYLOBACTERIOSIS (Campylobacter jejuni
ampylobacter jejuni)
The genus Campylobacter consists of at least species, and the one of primary importance in foods
is C. jejuni subsp. jejuni. Unlike C. jejuni subsp. doylei, it is resistant to cephalothin, can grow at
42
◦ C, and can reduce nitrates. Throughout this text, C. jejuni subsp. jejuni is referred to as C. jejuni.
of nonenterocolitica species, including Y. intermedia and Y. kristensenii, were positive for ST in two
other studies.
129,136 Y. bercovieri produces a heatstable enterotoxin (YbST), and detectable levels are
produced at 4
◦ C after 144–168 hours.
122
Although pathogenic strains of Y. enterocolitica produce ST, it appears that this agent is not critical
to virulence. Some evidence for the lack of importance of ST was provided by Schiemann,
112 who
demonstrated positive HeLa-cell and Sereny-test responses, with a 0:3 strain that did not produce
enterotoxin. On the other hand, each of 49 isolates belonging to serovar 0:3 and the other four virulent
serovars produced ST.
88 In addition to the diminished role of ST in Y. enterocolitica virulence, some
other properties now seem less important.
22,81 The Yop virulon is the most significant virulence factor
for yersiniae, and it along with some of the more recent findings on the pathogenesis of these organisms
is discussed in Chapter 22.
Incidence of Y. enterocolitica in Foods
This organism has been isolated from cakes, vacuum-packaged meats, seafood, vegetables, milk,
and other food products. It has been isolated also from beef, lamb, and pork.
77 Of all sources, swine
appears to be the major source of strains pathogenic for humans. More specifically, pig tonsils have
been found to be the primary sources of contamination of liver, heart, and kidneys.
43 The incidence
and growth of Y. enterocolitica in milk are presented in Chapter 7, and for meats in Chapter 4.
Gastroenteritis Syndrome and Incidence
In addition to gastroenteritis, this organism has been associated with human pseudoappendicitis,
mesenteric lymphadenitis, terminal ileitis, reactive arthritis, peritonitis, colon and neck abscesses,
cholecystis, and erythema nodosum. It has been recovered from urine, blood, cerebrospinal fluid, and
the eyes of infected individuals. It is, of course, recovered from the stools of gastroenteritis victims.
Only the gastroenteritis syndrome is addressed below.
There is a seasonal incidence associated with this syndrome, with the fewest outbreaks occurring
during the spring and the greatest number in October and November. The incidence is highest in the
very young and the old. In an outbreak studied by Gutman et al.,
49 the symptoms (and percentage
complaining of them) were fever (87), diarrhea (69), severe abdominal pain (62), vomiting (56),
pharyngitis (31), and headache (18). The outbreak led to two appendectomies and two deaths.
Milk (raw, improperly pasteurized, or recontaminated) is a common vehicle food. The first documented outbreak in the United States occurred in 1976 in New York State, with serovar 0:8 as the
responsible strain, and chocolate milk prepared by adding chocolate syrup to previously pasteurized
milk was the vehicle food.
12 An outbreak of serotype 0:3 among 15 children occurred in Georgia in
1988–1989; the vehicle food was raw chitterlings.
30
Symptoms of the gastroenteritis syndrome develop several days following ingestion of contaminated
foods and are characterized by abdominal pain and diarrhea. Children appear to be more susceptible
than adults, and the organisms may be present in stools for up to 40 days following illness.
4 A variety
of systemic involvements may occur as a consequence of the gastroenteritis syndrome.
CAMPYLOBACTERIOSIS (Campylobacter jejuni
ampylobacter jejuni)
The genus Campylobacter consists of at least species, and the one of primary importance in foods
is C. jejuni subsp. jejuni. Unlike C. jejuni subsp. doylei, it is resistant to cephalothin, can grow at
42
◦ C, and can reduce nitrates. Throughout this text, C. jejuni subsp. jejuni is referred to as C. jejuni.