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biothreat agents. Bacterial pathogens share similar strategies to cause disease. They
produce toxins that either kill or highjack host cell function. They also have specialized secretory systems, akin to molecular syringes, which directly inject “effector”
proteins that change mammalian cell signaling. In this chapter we will discuss some
of the main food borne bacterial pathogens and biothreat agents, as well as focusing
in the function of their toxins, and mode of action within the host cell.
9.2 Food-borne Pathogens
Bacterial food-borne pathogens are a major cause of gastroenteritis and diarrheal
diseases worldwide. The three main species responsible for the majority of outbreaks worldwide are Salmonella enterica, Campylobacter jejuni and E. coli.
Salmonella enterica causes food poisoning and enteric fever [2]. Food poisoning
by nontyphoidal Salmonella infections leads to diarrhea, fever, nausea, and cramps.
These symptoms usually resolve without treatment in 4–7 days. However, nontyphoidal infections have a large public health impact resulting in ~1.4 million infections, 16,000 hospitalizations, and 400–600 deaths annually in the US alone. The
economic impact has been estimated to be about $2.4 billion [3]. Most food poisonings are caused by Salmonella enterica serovar Typhimurium (S. Typhimurium) or
Salmonella enterica serovar Enteritidis (S. Enteritidis). Typhoid fever is caused by
Salmonella enterica serovar Typhi (S. Typhi) and although it is rare in the US, it is
very common in developing nations. Typhoid fever leads to fever, stomach pain,
weakness, cough, loss of appetite and mild diarrhea or constipation. An important
public health concern is that people can become carriers of S. Typhi, even after they
cease to have symptoms. Moreover, they can later relapse. It is also worrisome that
Salmonella has become increasingly resistant to multiple antibiotics [4–8].
Salmonella invades intestinal epithelial cells and replicates within macrophages
travelling from Payer’s Patches to systemic organs such as spleen and liver. Its virulence repertoire includes expression of two type three secretion systems (T3SSs),
which are molecular syringes that deliver several bacterial effector proteins within
the host cells. These effectors mimic or highjack host cell function, leading to cytoskeleton rearrangement, changes in signaling and immune responses among others.
The first T3SS promotes invasion of intestinal epithelial cells, which are nonphagocytic. The second T3SS allows for survival within macrophages through modifications of the vacuole. T3SS1 is involved in the intestinal phase, while T3SS2 is
mostly involved in systemic disease [9] (Fig. 9.1).
Campylobacter jejuni is estimated to cause about 1.3 million illnesses in the US
annually. C. jejuni is a food pathogen whose main reservoir is poultry. Infections are
usually linked to consumption of raw or undercooked poultry meat. C. jejuni causes
bloody diarrhea accompanied by fever and cramps. A severe and debilitating autoimmune complication known as Guillain-Barré syndrome may occur in some
patients [10]. C. jejuni is a pathogen for humans but a commensal in poultry. Its
V. Sperandio
biothreat agents. Bacterial pathogens share similar strategies to cause disease. They
produce toxins that either kill or highjack host cell function. They also have specialized secretory systems, akin to molecular syringes, which directly inject “effector”
proteins that change mammalian cell signaling. In this chapter we will discuss some
of the main food borne bacterial pathogens and biothreat agents, as well as focusing
in the function of their toxins, and mode of action within the host cell.
9.2 Food-borne Pathogens
Bacterial food-borne pathogens are a major cause of gastroenteritis and diarrheal
diseases worldwide. The three main species responsible for the majority of outbreaks worldwide are Salmonella enterica, Campylobacter jejuni and E. coli.
Salmonella enterica causes food poisoning and enteric fever [2]. Food poisoning
by nontyphoidal Salmonella infections leads to diarrhea, fever, nausea, and cramps.
These symptoms usually resolve without treatment in 4–7 days. However, nontyphoidal infections have a large public health impact resulting in ~1.4 million infections, 16,000 hospitalizations, and 400–600 deaths annually in the US alone. The
economic impact has been estimated to be about $2.4 billion [3]. Most food poisonings are caused by Salmonella enterica serovar Typhimurium (S. Typhimurium) or
Salmonella enterica serovar Enteritidis (S. Enteritidis). Typhoid fever is caused by
Salmonella enterica serovar Typhi (S. Typhi) and although it is rare in the US, it is
very common in developing nations. Typhoid fever leads to fever, stomach pain,
weakness, cough, loss of appetite and mild diarrhea or constipation. An important
public health concern is that people can become carriers of S. Typhi, even after they
cease to have symptoms. Moreover, they can later relapse. It is also worrisome that
Salmonella has become increasingly resistant to multiple antibiotics [4–8].
Salmonella invades intestinal epithelial cells and replicates within macrophages
travelling from Payer’s Patches to systemic organs such as spleen and liver. Its virulence repertoire includes expression of two type three secretion systems (T3SSs),
which are molecular syringes that deliver several bacterial effector proteins within
the host cells. These effectors mimic or highjack host cell function, leading to cytoskeleton rearrangement, changes in signaling and immune responses among others.
The first T3SS promotes invasion of intestinal epithelial cells, which are nonphagocytic. The second T3SS allows for survival within macrophages through modifications of the vacuole. T3SS1 is involved in the intestinal phase, while T3SS2 is
mostly involved in systemic disease [9] (Fig. 9.1).
Campylobacter jejuni is estimated to cause about 1.3 million illnesses in the US
annually. C. jejuni is a food pathogen whose main reservoir is poultry. Infections are
usually linked to consumption of raw or undercooked poultry meat. C. jejuni causes
bloody diarrhea accompanied by fever and cramps. A severe and debilitating autoimmune complication known as Guillain-Barré syndrome may occur in some
patients [10]. C. jejuni is a pathogen for humans but a commensal in poultry. Its
V. Sperandio