Staphylococcus aureus
Staphylococcal enteritis
Streptococcus
Vibrio cholerae, including O1 and non-O1
Vibrio parahaemolyticus
Vibrio vulnificus
Yersinia enterocolitica and Yersinia pseudotuberculosisLess common bacterial agents:
Brucella spp. Corynebacterium ulcerans
Coxiella burnetii or Q fever
Plesiomonas shigelloides

Enterotoxins
In addition to disease caused by direct bacterial infection, some foodborne illnesses are caused by enterotoxins (exotoxins targeting the intestines). Enterotoxins can produce illness even when the microbes that produced them have been killed. Symptom appearance varies with the toxin but may be rapid in onset, as in the case of enterotoxins of Staphylococcus aureus in which symptoms appear in one to six hours. This causes intense vomiting including or not including diarrhea (resulting in staphylococcal enteritis), and staphylococcal enterotoxins (most commonly staphylococcal enterotoxin A but also including staphylococcal enterotoxin B) are the most commonly reported enterotoxins although cases of poisoning are likely underestimated. It occurs mainly in cooked and processed foods due to competition with other biota in raw foods, and humans are the main cause of contamination as a substantial percentage of humans are persistent carriers of S. aureus. The CDC has estimated about 240,000 cases per year in the United States. Clostridium botulinum
Clostridium perfringens
Bacillus cereusThe rare but potentially deadly disease botulism occurs when the anaerobic bacterium Clostridium botulinum grows in improperly canned low-acid foods and produces botulin, a powerful paralytic toxin. Pseudoalteromonas tetraodonis, certain species of Pseudomonas and Vibrio, and some other bacteria, produce the lethal tetrodotoxin, which is present in the tissues of some living animal species rather than being a product of decomposition.
Infectious dose
The infectious dose is the amount of agent that must be consumed to give rise to symptoms of foodborne illness, and varies according to the agent and the consumers age and overall health. Pathogens vary in minimum infectious dose; for example, Shigella sonnei has a low estimated minimum dose of < 500 colony-forming units (CFU) while Staphylococcus aureus has a relatively high estimate.In the case of Salmonella a relatively large inoculum of 1 million to 1 billion organisms is necessary to produce symptoms in healthy human volunteers, as Salmonellae are very sensitive to acid. An unusually high stomach pH level (low acidity) greatly reduces the number of bacteria required to cause symptoms by a factor of between 10 and 100. Gut microbiota unaccustomed to endemic organisms
Foodborne illness often occurs as travelers diarrhea in persons whose gut microbiota is unaccustomed to organisms endemic to the visited region. This effect of microbiologic naivete is compounded by any food safety lapses in the foods preparation. Epidemiology
Asymptomatic subclinical infection may help spread these diseases, particularly Staphylococcus aureus, Campylobacter, Salmonella, Shigella, Enterobacter, Vibrio cholerae, and Yersinia. For example, as of 1984 it was estimated that in the United States, 200,000 people were asymptomatic carriers of Salmonella. Infants
Globally, infants are a group that is especially vulnerable to foodborne disease. The World Health Organization has issued recommendations for the preparation, use and storage of prepared formulas. Breastfeeding remains the best preventive measure for protection from foodborne infections in infants.