Viruses and Some Other Proven and Suspected Foodborne Biohazards 735
With regard to growth temperature and habitat, 7 of 13 strains displayed growth at 0–5
◦ C, 4 of
13 at 10
◦ C, and 1 at a minimum of 15
◦ C.
93 The psychrotrophs had optimum growth between 15
◦ C
and 20
◦ C. The maximum growth temperature for some strains was 40–45
◦ C with optimum at 35
◦ C.
46
Regarding distribution, the organism was found in all but 12 of 147 lotic and lentic habitats.
46 Four
of those habitats that did not yield the organism were either hypersaline lakes or geothermal springs.
Some waters contained up to 9,000/ml. An ecological study of A. hydrophila in the Chesapeake Bay
revealed numbers ranging from < 0.3/l–5 × 10
3 /ml in the water column, and about 4.6 × 10
2 /g of
sediment.
56 The presence of this organism correlated with total, aerobic, viable, and heterotrophic
bacterial counts, and its presence was inversely related to dissolved O 2 and salinity, with the upper
salt level being about 15%. Fewer were found during the winter than during the summer months. For
reviews, see references 2, 52. Their occurrence in some ready-to-eat foods is presented in Chapter 9
(Table 9–3).
Plesiomonas
P. shigelloides is found in surface waters and soil and has been recovered from fish, shellfish, other
aquatic animals, as well as from terrestrial meat animals. It differs from A. hydrophila in having G + C
content of DNA of 51%, versus 58–62% for A. hydrophila. It has been isolated by many investigators
from patients with diarrhea and is associated with other general infections in humans. It produces a
heat-stable enterotoxin, and serogroup 0:17 strains react with Shigella group D antisera.
1 In a study
of 16 strains from humans with intestinal illness, P. shigelloides did not always bind Congo red, the
strains were noninvasive in HEp-2 cells, and they did not produce Shiga-like toxin on Vero cells.
1
Although a low-level cytolysin was produced consistently, the mean LD 50 for outbred Swiss mice
was 3.5 × 10
8 cfu. Heat-stable enterotoxin was not produced by any of the 16 strains, and it was the
conclusion of these investigators that this organism possesses a low pathogenic potential.
1
P. shigelloides was recovered by Zajc-Satler et al.
118 from the stools of six diarrheal patients. It
was believed to be the etiological agent, although salmonellae were recovered from two patients. Two
outbreaks of acute diarrheal disease occurred in Osaka, Japan, in 1973 and 1974, and the only bacterial
pathogen recovered from stools was P. shigelloides. In the 1973 outbreak, 978 of 2,141 persons became
ill, with 88% complaining of diarrhea, 82% of abdominal pain, 22% of fever, and 13% of headaches.
107
The symptoms lasted 2 to 3 days. Of 124 stools examined, 21 yielded P. shigelloides 017:H2. The
same serovar was recovered from tap water. In the 1974 outbreak, 24 of 35 persons became ill with
symptoms similar to those noted. P. shigelloides serovar 024:H5 was recovered from three of eight
stools “virtually in pure culture.”
107 The organism was recovered from 39% of 342 water and mud
samples, as well as from fish, shellfish, and newts.
A 15-year-old female contracted gastroenteritis, and 6 hours after she took one tablet of
trimethoprim-sulfadiazine, P. shigelloides could be recovered from her blood.
87 The latter investigators noted that 10 of the previously known 12 cases of P. shigelloides bacteremia were in patients
who were either immunocompromised or presented with other similar conditions. The 15-year-old
had a temperature of 39
◦ C and passed up to 10 watery stools daily. The isolated strain reacted with
S. dysenteriae serotype 7 antiserum, placing it in O group 22 of P. shigelloides.
83
Growth of P. shigelloides has been observed at 10
◦ C,
93 and 59% of 59 fish from Zaire waters
contained the organism.
111 In the latter study, the organism was found more in river fish than lake fish. It
appeared not to produce an enterotoxin since only 4 of 29 isolates produced positive responses in rabbit
ileal loops.
95 Foodborne cases have not been documented, but the organism has been incriminated in
at least two outbreaks.
73
With regard to growth temperature and habitat, 7 of 13 strains displayed growth at 0–5
◦ C, 4 of
13 at 10
◦ C, and 1 at a minimum of 15
◦ C.
93 The psychrotrophs had optimum growth between 15
◦ C
and 20
◦ C. The maximum growth temperature for some strains was 40–45
◦ C with optimum at 35
◦ C.
46
Regarding distribution, the organism was found in all but 12 of 147 lotic and lentic habitats.
46 Four
of those habitats that did not yield the organism were either hypersaline lakes or geothermal springs.
Some waters contained up to 9,000/ml. An ecological study of A. hydrophila in the Chesapeake Bay
revealed numbers ranging from < 0.3/l–5 × 10
3 /ml in the water column, and about 4.6 × 10
2 /g of
sediment.
56 The presence of this organism correlated with total, aerobic, viable, and heterotrophic
bacterial counts, and its presence was inversely related to dissolved O 2 and salinity, with the upper
salt level being about 15%. Fewer were found during the winter than during the summer months. For
reviews, see references 2, 52. Their occurrence in some ready-to-eat foods is presented in Chapter 9
(Table 9–3).
Plesiomonas
P. shigelloides is found in surface waters and soil and has been recovered from fish, shellfish, other
aquatic animals, as well as from terrestrial meat animals. It differs from A. hydrophila in having G + C
content of DNA of 51%, versus 58–62% for A. hydrophila. It has been isolated by many investigators
from patients with diarrhea and is associated with other general infections in humans. It produces a
heat-stable enterotoxin, and serogroup 0:17 strains react with Shigella group D antisera.
1 In a study
of 16 strains from humans with intestinal illness, P. shigelloides did not always bind Congo red, the
strains were noninvasive in HEp-2 cells, and they did not produce Shiga-like toxin on Vero cells.
1
Although a low-level cytolysin was produced consistently, the mean LD 50 for outbred Swiss mice
was 3.5 × 10
8 cfu. Heat-stable enterotoxin was not produced by any of the 16 strains, and it was the
conclusion of these investigators that this organism possesses a low pathogenic potential.
1
P. shigelloides was recovered by Zajc-Satler et al.
118 from the stools of six diarrheal patients. It
was believed to be the etiological agent, although salmonellae were recovered from two patients. Two
outbreaks of acute diarrheal disease occurred in Osaka, Japan, in 1973 and 1974, and the only bacterial
pathogen recovered from stools was P. shigelloides. In the 1973 outbreak, 978 of 2,141 persons became
ill, with 88% complaining of diarrhea, 82% of abdominal pain, 22% of fever, and 13% of headaches.
107
The symptoms lasted 2 to 3 days. Of 124 stools examined, 21 yielded P. shigelloides 017:H2. The
same serovar was recovered from tap water. In the 1974 outbreak, 24 of 35 persons became ill with
symptoms similar to those noted. P. shigelloides serovar 024:H5 was recovered from three of eight
stools “virtually in pure culture.”
107 The organism was recovered from 39% of 342 water and mud
samples, as well as from fish, shellfish, and newts.
A 15-year-old female contracted gastroenteritis, and 6 hours after she took one tablet of
trimethoprim-sulfadiazine, P. shigelloides could be recovered from her blood.
87 The latter investigators noted that 10 of the previously known 12 cases of P. shigelloides bacteremia were in patients
who were either immunocompromised or presented with other similar conditions. The 15-year-old
had a temperature of 39
◦ C and passed up to 10 watery stools daily. The isolated strain reacted with
S. dysenteriae serotype 7 antiserum, placing it in O group 22 of P. shigelloides.
83
Growth of P. shigelloides has been observed at 10
◦ C,
93 and 59% of 59 fish from Zaire waters
contained the organism.
111 In the latter study, the organism was found more in river fish than lake fish. It
appeared not to produce an enterotoxin since only 4 of 29 isolates produced positive responses in rabbit
ileal loops.
95 Foodborne cases have not been documented, but the organism has been incriminated in
at least two outbreaks.
73