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