• Most virulent strain of E. coli

• Enterohemorrhagic E. coli

• Symptoms range from mild gastroenteritis with fever to bloody diarrhea

• About 10% of patients develop hemolytic uremic syndrome (can cause kidney damage and failure)

• Can also cause neurological symptoms such as blindness, seizure, and stroke

• Four other categories: Enterotoxigenic Enteroinvasive Enteropathogenic Enteroaggregative

Presentation varies depending on which type of E. coli is causing the disease

Traveler’s diarrhea: watery diarrhea, low-grade fever, nausea, and vomiting

Cause a disease similar to Shigella dysentery

Invade gut mucosa and cause widespread destruction

Blood and pus found in stool Significant fever

Profuse, watery diarrhea Fever and vomiting also common Produce effacement of gut surfaces

Can cause chronic diarrhea in young children and in AIDS patients

• Most common bacterial cause of diarrhea in the U.S.

• Frequent watery stools, fever, vomiting, headaches, and severe abdominal pain

• Symptoms may last beyond 2 weeks

• Symptoms may subside then recur over a period of weeks

• In a small number of cases, can lead to a serious neuromuscular paralysis called Guillain-Barré syndrome (GBS)

Y. enterocolitica and Y. pseudotuberculosis

Uncommon in U.S. Inflammation of the

ileum and mesenteric lymph nodes gives rise to severe abdominal pain

Infection occasionally spreads to the bloodstream

• Causes pseudomembranous colitis

• Major cause of diarrhea in hospitals

• Able to superinfect the large intestine when drugs have disrupted the normal biota

• Produces two enterotoxins (toxins A and B) that cause areas of necrosis in the wall of the intestine

• Diarrhea• Severe cases exhibit

abdominal cramps, fever, and leukocytosis

Incubation period of a few hours to a few days

Symptoms begin abruptly with vomiting

Followed by copious watery feces called secretory diarrhea

Can lose up to 1 liter of fluid an hour in severe cases

Headache, sweating, vomiting, severe abdominal cramps, and diarrhea

In AIDS patients may develop into chronic persistent cryptosporidial diarrhea

• Effects of infection vary with age, nutritional state, general health, and living conditions of the patient

Many other viruses can cause gastroenteritis

For example adenoviruses, noroviruses, and astroviruses

Common in the U.S. and around the world Profuse, water diarrhea of 3 to 5 days

duration

Symptoms in the gut that are caused by a preformed toxin of some sort

If the symptoms are violent and the incubation period is very short, intoxication rather than infection should be considered

• Associated with food such as custards, sauces, cream pastries, processed meats, chicken salad, potatoe salad, or ham that have been contaminated and then left unrefrigerated for a few hours

• Toxins do not noticeably alter the food’s taste or smell

• Heating the food after toxin production may not prevent disease

• Symptoms: cramping, nausea, vomiting, and diarrhea

• Rapid recovery- usually within 24 hours

• Two exotoxins: one causes diarrheal-type disease, the other cause an emetic disease

• The type of disease that takes place is influenced by the type of food that is contaminated

• Emetic form frequently linked to fried rice, especially when cooked and kept warm for long periods of time

• Diarrheal form associated with carbohydrate dishes, cook meats or vegetables that are held at a warm temperature for long periods of time

Animal flesh and vegetables such as beans that have not been cooked thoroughly enough to destroy endospores

Acute abdominal pain, diarrhea, and nausea in 8 to 16 hours

Rapid recovery

Incubation period of about 1 week

Watery diarrhea, stomach cramps, bloating, fever, and muscle aches

If prolonged, also experience anorexia and weight loss

Diarrhea of long duration, abdominal pain, and flatulence

Stools have a greasy, malodorous quality

Fever usually not present

• Clinical amoebiasis exists in intestinal and extraintestinal forms

• Intestinal targets: ceacum, appendix, colon, and rectum– Secretes enzymes that dissolve

tissues– Leaves erosive ulcerations as it

penetrates deeper layer of mucosa– Dysentery, abdominal pain, fever,

diarrhea, weight loss– Can also manifest hemorrhage,

perforation, appendicitis, and amoebomas

• Extraintestinal: common target is the liver– Amoebic hepatitis– Rarer complication- pulmonary

amoebiasis