660 Modern Food Microbiology
tdh gene has been determined,
94 and a specific tdh gene probe constructed, which consists of a 406base pair.
93 Employing this probe, 141 V. parahaemolyticus strains were tested. All K
+ strains were
gene-positive—86% of them were weak positives—and 16% of K
− strains reacted with the probe. All
gene-positive strains produced TDH as assessed by an enzyme-linked immunosorbent assay (ELISA).
Of 129 other vibrios tested with the gene probe, including 19 named Vibrio spp., only V. hollisae was
positive.
93 The transfer of R plasmids from E. coli to V. parahaemolyticus has been demonstrated.
48
Some clinical isolates that lack TDH contain the TDH-related hemolysin TRH (encoded by trh). Most
isolates of V. parahaemolyticus from coastal waters of the United States contained both tdh and trh
along with urease.
37
At least 12 O antigens and 59 K antigens have been identified, but no correlations have been made
between these and K
+ and K
− strains, and the value of serotyping as an epidemiological aid has been
minimal.
Because not all K
+ strains produce positive responses in the rabbit ileal loop assay and because some
K
− strains are associated with gastroenteritis and sometimes are the only strains isolated, the precise
virulence mechanisms are unclear. In the U.S. Pacific Northwest, K
− but urease-positive strains are
associated with the syndrome.
69 Of 45 human fecal isolates in California and Mexico, 71% of 45 were
urease positive, 91% were K
+ , and the serovar was 04:K12.
1
Adherence to epithelial cells is an important virulence property of Gram-negative bacteria, and it appears that V. parahaemolyticus produces cell-associated hemagglutinins that correlate with adherence
to intestinal mucosa.
141 Pili (fimbriae) also play a role in intestinal tract colonization.
90
Gastroenteritis Syndrome and Vehicle Foods
The identity of V. parahaemolyticus as a foodborne gastroenteritis agent was made first by Fujino in
1951.
45 Whereas the incidence of this illness is low in the United States and some European countries,
it is high in Japan, accounting for 24% of bacterial food poisoning between 1965 and 1974.
13,110 The
1951 outbreak in Japan was traced to a boiled and semidried young sardines preparation, with 272
victims and 20 deaths.
110 The next two outbreaks occurred in Japan in 1956 and 1960.
110 In Korea and
Japan, vibriosis accounted for 13.5% and 23.2%, respectively of all cases of foodborne illness during
the years 1981–1995.
76 The respective percent of outbreaks were 17.4 and 32.3 in the two countries.
The first outbreak in the United States occurred in 1971.
86 Steamed crabs and crab salad were the
vehicle foods, and 425 of approximately 745 persons at risk became ill. The isolate from victims was
K
+ and serotype 04:K11. Synopses of several outbreaks are presented below.
1. 1998. V. parahaemolyticus was the etiological agent among 23 persons living in Connecticut,
New Jersey, and New York who ate raw oysters and clams harvested at Long Island Sound, NY.
23
2. 1997. Raw oysters were the source of Vibrio parahaemolyticus in this outbreak in British
Columbia, Washington, Oregon, and California, and there were 209 victims.
25
3. 1981–1994. A study of raw oyster-associated infections in Florida between 1981 and 1994
included 237 (70%) with gastroenteritis and two deaths, and 102 (30%) who developed primary
septicemia. Of the latter, 49% died and 80% of these were caused by Vibrio vulnificus.
55 Regarding
species, 29% of the infections were caused by V. parahaemolyticus, 28% by V. cholerae non-01,
15% by V. hollisae, and 12% by V. mimicus.
55
In regard to symptomatology, findings from a 1978 outbreak in Louisiana illustrate the typical
features. The mean incubation period was 16.7 hours (range, 3–76 hours); symptoms lasted from 1
tdh gene has been determined,
94 and a specific tdh gene probe constructed, which consists of a 406base pair.
93 Employing this probe, 141 V. parahaemolyticus strains were tested. All K
+ strains were
gene-positive—86% of them were weak positives—and 16% of K
− strains reacted with the probe. All
gene-positive strains produced TDH as assessed by an enzyme-linked immunosorbent assay (ELISA).
Of 129 other vibrios tested with the gene probe, including 19 named Vibrio spp., only V. hollisae was
positive.
93 The transfer of R plasmids from E. coli to V. parahaemolyticus has been demonstrated.
48
Some clinical isolates that lack TDH contain the TDH-related hemolysin TRH (encoded by trh). Most
isolates of V. parahaemolyticus from coastal waters of the United States contained both tdh and trh
along with urease.
37
At least 12 O antigens and 59 K antigens have been identified, but no correlations have been made
between these and K
+ and K
− strains, and the value of serotyping as an epidemiological aid has been
minimal.
Because not all K
+ strains produce positive responses in the rabbit ileal loop assay and because some
K
− strains are associated with gastroenteritis and sometimes are the only strains isolated, the precise
virulence mechanisms are unclear. In the U.S. Pacific Northwest, K
− but urease-positive strains are
associated with the syndrome.
69 Of 45 human fecal isolates in California and Mexico, 71% of 45 were
urease positive, 91% were K
+ , and the serovar was 04:K12.
1
Adherence to epithelial cells is an important virulence property of Gram-negative bacteria, and it appears that V. parahaemolyticus produces cell-associated hemagglutinins that correlate with adherence
to intestinal mucosa.
141 Pili (fimbriae) also play a role in intestinal tract colonization.
90
Gastroenteritis Syndrome and Vehicle Foods
The identity of V. parahaemolyticus as a foodborne gastroenteritis agent was made first by Fujino in
1951.
45 Whereas the incidence of this illness is low in the United States and some European countries,
it is high in Japan, accounting for 24% of bacterial food poisoning between 1965 and 1974.
13,110 The
1951 outbreak in Japan was traced to a boiled and semidried young sardines preparation, with 272
victims and 20 deaths.
110 The next two outbreaks occurred in Japan in 1956 and 1960.
110 In Korea and
Japan, vibriosis accounted for 13.5% and 23.2%, respectively of all cases of foodborne illness during
the years 1981–1995.
76 The respective percent of outbreaks were 17.4 and 32.3 in the two countries.
The first outbreak in the United States occurred in 1971.
86 Steamed crabs and crab salad were the
vehicle foods, and 425 of approximately 745 persons at risk became ill. The isolate from victims was
K
+ and serotype 04:K11. Synopses of several outbreaks are presented below.
1. 1998. V. parahaemolyticus was the etiological agent among 23 persons living in Connecticut,
New Jersey, and New York who ate raw oysters and clams harvested at Long Island Sound, NY.
23
2. 1997. Raw oysters were the source of Vibrio parahaemolyticus in this outbreak in British
Columbia, Washington, Oregon, and California, and there were 209 victims.
25
3. 1981–1994. A study of raw oyster-associated infections in Florida between 1981 and 1994
included 237 (70%) with gastroenteritis and two deaths, and 102 (30%) who developed primary
septicemia. Of the latter, 49% died and 80% of these were caused by Vibrio vulnificus.
55 Regarding
species, 29% of the infections were caused by V. parahaemolyticus, 28% by V. cholerae non-01,
15% by V. hollisae, and 12% by V. mimicus.
55
In regard to symptomatology, findings from a 1978 outbreak in Louisiana illustrate the typical
features. The mean incubation period was 16.7 hours (range, 3–76 hours); symptoms lasted from 1