Microbiology: A Systems Approach, 2nd ed'

1
Microbiology A Systems Approach, 2nd ed.

• Chapter 22 The Gastrointestinal Tract and Its
  Defenses

2
Acute Diarrhea Caused by E.coli O157H7 (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

3
Figure 22.12
4
Acute Diarrhea Caused by Other E. coli

• Four other categories
• Enterotoxigenic
• Enteroinvasive
• Enteropathogenic
• Enteroaggregative

5
Enterotoxigenic E. coli (ETEC)

• Presentation varies depending on which type of E.
  coli is causing the disease
• Travelers diarrhea watery diarrhea, low-grade
  fever, nausea, and vomiting

6
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

7
Enteropathogenic E. coli (EPEC)

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

8
Enteroaggregative E. coli (EAEC)

• Can cause chronic diarrhea in young children and
  in AIDS patients

9
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)

10
Figure 22.13
11
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

12
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

13
Figure 22.14
14
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

15
Figure 22.15
16
Acute Diarrhea Caused by Cryptosporidium

• Headache, sweating, vomiting, severe abdominal
  cramps, and diarrhea
• In AIDS patients may develop into chronic
  persistent cryptosporidial diarrhea

17
Figure 22.16
18
Figure 22.17
19
Acute Diarrhea Caused by Rotavirus

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

20
Figure 22.18
21
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

22
(No Transcript)
23
(No Transcript)
24
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

25
Food Poisoning by Staphylococus aureus Exotoxin

• Associated with food such as custards, sauces,
  cream pastries, processed meats, chcken salad, or
  ham that have been contaminated and then left
  unrefrigerated for a few hours
• Toxins do not noticeably alter the foods 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

26
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 cook mats or
  vegetables that are held at a warm temperature
  for long periods of time

27
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

28
(No Transcript)