The Gastrointestinal Tract and Its Defenses Lecture Two

The Gastrointestinal Tract and Its Defenses Lecture Two

Acute Diarrhea Caused by E. coli O 157: H 7 (EHEC) • • • 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

Acute Diarrhea Caused by Other E. coli • Four other categories: Enterotoxigenic Enteroinvasive Enteropathogenic Enteroaggregative

Enterotoxigenic E. coli (ETEC) Presentation varies depending on which type of E. coli is causing the disease Traveler’s diarrhea: watery diarrhea, lowgrade fever, nausea, and vomiting

Enteroinvasive E. coli (EIEC) Cause a disease similar to Shigella dysentery Invade gut mucosa and cause widespread destruction Blood and pus found in stool Significant fever

Enteropathogenic E. coli (EPEC) Profuse, watery diarrhea Fever and vomiting also common Produce effacement of gut surfaces

Enteroaggregative E. coli (EAEC) Can cause chronic diarrhea in young children and in AIDS patients

Acute Diarrhea Caused by Campylobacter • • • 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)

Acute Diarrhea Caused by Yersinia Species 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

Acute Diarrhea Caused by Clostridium difficile • • • 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

Acute Diarrhea Caused by Vibrio cholera 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

Acute Diarrhea Caused by Cryptosporidium Headache, sweating, vomiting, severe abdominal cramps, and diarrhea In AIDS patients may develop into chronic persistent cryptosporidial diarrhea

Acute Diarrhea Caused by Rotavirus • Effects of infection vary with age, nutritional state, general health, and living conditions of the patient

Acute Diarrhea Caused by Other Viruses 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

Acute Diarrhea with Vomiting (Food Poisoning) 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

Food Poisoning by Staphylococus aureus Exotoxin • • • 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 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

Food Poisoning by Bacillus cereus Exotoxin • • 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

Food Poisoning by Clostridum perfringens Exotoxin 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

Chronic Diarrhea by Cyclospora Incubation period of about 1 week Watery diarrhea, stomach cramps, bloating, fever, and muscle aches If prolonged, also experience anorexia and weight loss

Chronic Diarrhea by Giardia Diarrhea of long duration, abdominal pain, and flatulence Stools have a greasy, malodorous quality Fever usually not present

Chronic Diarrhea by Entamoeba • • 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