358 ◾ Fundamental Food Microbiology
diced, or cut prior to eating, such as vegetables used in salads, have also been involved in outbreaks. Shellfish harvested from sewage-polluted water and eaten raw have been associated with
shigellosis. Many foods support their growth. As the infective dose is very low, growth in food is
probably not an important factor for the disease.
Prevention
Foodborne shigellosis, at least in the developed countries, is caused by contamination of foods by
food handlers shedding the pathogen in the feces and having poor personal hygiene. To prevent
contamination of ready-to-eat food by such individuals, it is necessary to forbid them to handle
such foods. Quite often, this is impossible, especially if the individual is a carrier. Proper education
of the food handlers about the importance of good personal hygiene and the need to not handle
food if one suspects having a digestive disorder is important. Use of rigid sanitary standards to
prevent cross-contamination of ready-to-eat food, use of properly chlorinated water to wash vegetables to be used for salads, and refrigeration of foods are necessary to reduce foodborne shigellosis. Vaccination of children in developing countries to control Shigellosis have been proposed. 30
Campylobacter Species 31
Importance
Genus Campylobacter contains 16 species and six subspecies, and many of them cause human gastroenteritis; however, Cam. jejuni and Cam. coli are considered the most common causative agents
of human diarrheal disease in many countries worldwide. In many countries, the number of cases
of campylobacteriosis probably far exceeds the combined number of salmonellosis and shigellosis
cases. Epidemiological data have confirmed this in Canada, the U.K., and Scotland. Isolation
of Campylobacter spp. from a suspected sample requires specific methods. After developing the
method and incorporating it to isolate suspected foodborne pathogens, Cam. jejuni has been confirmed as a causative agent in many foodborne illnesses. Since it was first recognized as the cause
of an outbreak in 1979, Cam. jejuni has been implicated in 53 foodborne outbreaks in the United
States between 1979 and 1987, affecting 1547 individuals and resulting in two deaths. In 2009
and 2010, Campylobacter spp. was responsible for 13 and 21 outbreaks, respectively, in the United
States, resulting in 600 illnesses. 32 It is now estimated that Campylobacter causes about 845,000
cases with 76 deaths annually in the United States. 29 The foods implicated most often in campylobacteriosis were raw milk and improperly cooked chicken. Although several Campylobacter spp.
have been associated with foodborne campylobacteriosis, Cam. jejuni has been isolated in most
incidents; the discussion here is on Cam. jejuni.
Characteristics
Cam. jejuni is a gram-negative, motile, nonsporulating, rod-shaped bacterium. The cells are small,
fragile, and spirally curved. The strains are microaerophilic and catalase and oxidase positive. The
strains require a microaerophilic environment of approximately 5% oxygen, 8% CO 2 , and 87%
N 2 for growth. Growth temperature ranges between 32°C and 45°C with optimum approximately
42°C. They grow better in amino acids than in carbohydrates. They generally grow slowly and are
not good competitors while growing with other bacteria. They generally do not grow well in many
diced, or cut prior to eating, such as vegetables used in salads, have also been involved in outbreaks. Shellfish harvested from sewage-polluted water and eaten raw have been associated with
shigellosis. Many foods support their growth. As the infective dose is very low, growth in food is
probably not an important factor for the disease.
Prevention
Foodborne shigellosis, at least in the developed countries, is caused by contamination of foods by
food handlers shedding the pathogen in the feces and having poor personal hygiene. To prevent
contamination of ready-to-eat food by such individuals, it is necessary to forbid them to handle
such foods. Quite often, this is impossible, especially if the individual is a carrier. Proper education
of the food handlers about the importance of good personal hygiene and the need to not handle
food if one suspects having a digestive disorder is important. Use of rigid sanitary standards to
prevent cross-contamination of ready-to-eat food, use of properly chlorinated water to wash vegetables to be used for salads, and refrigeration of foods are necessary to reduce foodborne shigellosis. Vaccination of children in developing countries to control Shigellosis have been proposed. 30
Campylobacter Species 31
Importance
Genus Campylobacter contains 16 species and six subspecies, and many of them cause human gastroenteritis; however, Cam. jejuni and Cam. coli are considered the most common causative agents
of human diarrheal disease in many countries worldwide. In many countries, the number of cases
of campylobacteriosis probably far exceeds the combined number of salmonellosis and shigellosis
cases. Epidemiological data have confirmed this in Canada, the U.K., and Scotland. Isolation
of Campylobacter spp. from a suspected sample requires specific methods. After developing the
method and incorporating it to isolate suspected foodborne pathogens, Cam. jejuni has been confirmed as a causative agent in many foodborne illnesses. Since it was first recognized as the cause
of an outbreak in 1979, Cam. jejuni has been implicated in 53 foodborne outbreaks in the United
States between 1979 and 1987, affecting 1547 individuals and resulting in two deaths. In 2009
and 2010, Campylobacter spp. was responsible for 13 and 21 outbreaks, respectively, in the United
States, resulting in 600 illnesses. 32 It is now estimated that Campylobacter causes about 845,000
cases with 76 deaths annually in the United States. 29 The foods implicated most often in campylobacteriosis were raw milk and improperly cooked chicken. Although several Campylobacter spp.
have been associated with foodborne campylobacteriosis, Cam. jejuni has been isolated in most
incidents; the discussion here is on Cam. jejuni.
Characteristics
Cam. jejuni is a gram-negative, motile, nonsporulating, rod-shaped bacterium. The cells are small,
fragile, and spirally curved. The strains are microaerophilic and catalase and oxidase positive. The
strains require a microaerophilic environment of approximately 5% oxygen, 8% CO 2 , and 87%
N 2 for growth. Growth temperature ranges between 32°C and 45°C with optimum approximately
42°C. They grow better in amino acids than in carbohydrates. They generally grow slowly and are
not good competitors while growing with other bacteria. They generally do not grow well in many