362 ◾ Fundamental Food Microbiology
does the Yst enterotoxin cause fluid secretion in the intestine. The pathogenic strains vary in serological characteristics. In the United States, the most common serovar implicated in yersiniosis is 0:8.
Disease and Symptoms 34,37
Foods that are incriminated for yersiniosis are generally cycled through refrigeration. Thus, the
bacterium has to adapt in the human host (37°C) prior to initiating infection. Generally, a high
dose (>10 4 cells) is required for the disease. Once ingested, the bacterium adheres and colonizes
in the small intestine using adhesion factor YadA and is taken up by M cells in the Peyer’s patch.
Engulfed bacteria are then released from the M cells in the basal layer and invade epithelial
cells using the Invasin protein and YadA. Bacteria survive inside the macrophages and spread to
the regional lymph nodes, liver, and spleen. In the intestine, the enterotoxin Yst promotes fluid
secretion, resulting in diarrhea. Young children are more susceptible to foodborne yersiniosis.
Symptoms are severe abdominal pain at the lower quadrant of the abdomen mimicking appendicitis, diarrhea, nausea, vomiting, and fever. Yersinia multiplies in mesenteric lymph nodes leading
to lymphadenitis, which can lead to appendicitis. Symptoms generally appear 24–30 hours following consumption of a contaminated food and last two to three days. The disease can be fatal
in rare cases. Severity of infection is pronounced in immunocompromised hosts as septicemia,
pneumonia, meningitis, endocarditis, and so forth. Long-term sequelae of yersiniosis is manifested
as reactive arthritis and erythema nodosum.
Food Association 38,39
Yer. enterocolitica strains are found in the environment; thus many foods can harbor the organism. However, pork products are the most common source for this organism. It has been isolated
from raw milk, processed dairy products, raw and improperly cooked meats, chitterling, fresh
vegetables, and improperly chlorinated water. Foods implicated in yersiniosis include raw and
pasteurized milk, ice cream, and improperly cooked meats. Because the cells are heat sensitive, a
properly pasteurized or heated food can have this pathogen from recontamination following heat
treatment. A food can also be contaminated from a human carrier or a pet. As the cells can grow
at refrigerated temperatures, even a low initial load can reach a high level during extended storage
of refrigerated foods.
Prevention
Because the strains are psychrotrophs, refrigeration cannot be used to control their growth. Good
sanitation at all phases of handling and processing and proper heat treatment are important to
control the occurrence of yersiniosis. Consumption of raw milk or meat cooked at low temperatures should be avoided.
Vibrio Species
The genus Vibrio is comprised of 30 species, and four species have been implicated in foodborne
illnesses: Vibrio cholerae (O1 and non-O1 serogroups), Vib. mimicus, Vib. parahaemolyticus, and
Vib. vulnificus. Vib. parahaemolyticus and Vib. vulnificus are discussed in this section, and Vib.
cholera and Vib. mimicus are included in the toxico-infection section (Chapter 27). Although there
does the Yst enterotoxin cause fluid secretion in the intestine. The pathogenic strains vary in serological characteristics. In the United States, the most common serovar implicated in yersiniosis is 0:8.
Disease and Symptoms 34,37
Foods that are incriminated for yersiniosis are generally cycled through refrigeration. Thus, the
bacterium has to adapt in the human host (37°C) prior to initiating infection. Generally, a high
dose (>10 4 cells) is required for the disease. Once ingested, the bacterium adheres and colonizes
in the small intestine using adhesion factor YadA and is taken up by M cells in the Peyer’s patch.
Engulfed bacteria are then released from the M cells in the basal layer and invade epithelial
cells using the Invasin protein and YadA. Bacteria survive inside the macrophages and spread to
the regional lymph nodes, liver, and spleen. In the intestine, the enterotoxin Yst promotes fluid
secretion, resulting in diarrhea. Young children are more susceptible to foodborne yersiniosis.
Symptoms are severe abdominal pain at the lower quadrant of the abdomen mimicking appendicitis, diarrhea, nausea, vomiting, and fever. Yersinia multiplies in mesenteric lymph nodes leading
to lymphadenitis, which can lead to appendicitis. Symptoms generally appear 24–30 hours following consumption of a contaminated food and last two to three days. The disease can be fatal
in rare cases. Severity of infection is pronounced in immunocompromised hosts as septicemia,
pneumonia, meningitis, endocarditis, and so forth. Long-term sequelae of yersiniosis is manifested
as reactive arthritis and erythema nodosum.
Food Association 38,39
Yer. enterocolitica strains are found in the environment; thus many foods can harbor the organism. However, pork products are the most common source for this organism. It has been isolated
from raw milk, processed dairy products, raw and improperly cooked meats, chitterling, fresh
vegetables, and improperly chlorinated water. Foods implicated in yersiniosis include raw and
pasteurized milk, ice cream, and improperly cooked meats. Because the cells are heat sensitive, a
properly pasteurized or heated food can have this pathogen from recontamination following heat
treatment. A food can also be contaminated from a human carrier or a pet. As the cells can grow
at refrigerated temperatures, even a low initial load can reach a high level during extended storage
of refrigerated foods.
Prevention
Because the strains are psychrotrophs, refrigeration cannot be used to control their growth. Good
sanitation at all phases of handling and processing and proper heat treatment are important to
control the occurrence of yersiniosis. Consumption of raw milk or meat cooked at low temperatures should be avoided.
Vibrio Species
The genus Vibrio is comprised of 30 species, and four species have been implicated in foodborne
illnesses: Vibrio cholerae (O1 and non-O1 serogroups), Vib. mimicus, Vib. parahaemolyticus, and
Vib. vulnificus. Vib. parahaemolyticus and Vib. vulnificus are discussed in this section, and Vib.
cholera and Vib. mimicus are included in the toxico-infection section (Chapter 27). Although there