Microbiology: A Systems Approach, 2nd ed'

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Microbiology A Systems Approach, 2nd ed.

• Chapter 22 The Gastrointestinal Tract and Its
  Defenses

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Chronic Diarrhea

• Lasting longer than 14 days
• Infectious or noninfectious
• AIDS patients suffer from it due to opportunistic
  infections
• Several microbes can be responsible

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Chronic Diarrhea by Enteroaggregative E. Coli
(EAEC)

• Adheres to human cells in aggregates rather than
  as single cells
• Stimulates large amounts of mucus in the gut

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Figure 22.19
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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

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Figure 22.20
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Chronic Diarrhea by Giardia

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

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Figure 22.21
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Chronic Diarrhea by Entamoeba

• Clinical amoebiasis exists in intestinal and
  extraintestinal forms
• Intestinal targets cecum, appendix, colon, and
  rectum
• Secretes enzymes that dissolve tissues
• Leaves erosive ulcerations as it penetrates deper
  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

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Figure 22.22
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Figure 22.23
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Figure 22.24
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Hepatitis

• Inflammatory disease marked by necrosis of
  hepatocytes and a mononuclear response that
  swells and disrupts the liver architecture
• Occurs when certain viruses infect the liver
• Causes jaundice when bilirubin accumulates in the
  blood and tissues

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Hepatitis A Virus (HAV)

• In general, far milder and shorter term than the
  other forms
• Either subclinical or vague, flulike symptoms
• In some cases, may include jaundice and swollen
  liver
• Darkened urine often seen
• Not oncogenic
• Complete uncomplicated recovery

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Hepatitis B Virus (HBV)

• May include fever, chills, malaise, anorexia,
  abdominal discomfort, diarrhea, and nausea
• Rashes may appear
• Arthritis may occur
• Can be serious and life-threatening
• Some patients develop glomerulonephritis and
  arterial inflammation
• Complete liver regeneration and restored function
  occur in most patients
• Small number of patients develop chronic liver
  disease (necrosis or cirrhosis)

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Hepatitis C Virus (HCV)

• silent epidemic
• Takes many years to cause noticeable symptoms
• Shares many symptoms of HAB but is more likely to
  become chronic
• Cancer may also result

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