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  1. What are the three most common bacterial causes of infectious diarrhea, and how are these infections contracted?

  2. Which test is useful for differentiating viral from bacterial diarrhea?

  3. How does Clostridium difficile cause diarrhea, and how is pseudomembranous colitis diagnosed?

  4. What are the findings that suggest the development of spontaneous peritonitis?

  5. How do abdominal abscesses usually form, and how are they best managed?

  6. Which pathogen most commonly causes peptic ulcer disease?

  7. How do hepatic abscesses usually develop, and which bacteria are most commonly cultured?

  8. What are the three most common forms of viral hepatitis, and how are they contracted?

  9. What are the major complications of viral hepatitis?



Can be life-threatening in infants, young children, and elderly people. Most individuals with this illness can be managed as outpatients.

Diarrheal illness is one of the leading causes of death among children <5 years of age worldwide accounting for 525,000 deaths annually and reflecting the limited resources in developing countries. Diarrhea is a less serious problem in the United States and other developed countries. However, despite higher levels of hygiene the incidence of diarrhea in the United States has been estimated to be one episode per person per year emphasizing the large worldwide burden of diarrheal disease.

With appropriate medical care, these infections are rarely fatal. The pathogens that cause diarrhea can be transmitted through food, through water, or through person-to-person spread. Differences in these modes of transmission reflect differences in the ability of each pathogen to survive in the environment. They also reflect the inoculum size required for a given pathogen to cause disease.


Bacterial Diarrhea


These disorders are usually self-limiting, but can be fatal in infants, elderly people, and people who develop enteric fever.

The three most common bacterial causes of acute infectious diarrhea are Salmonella, Shigella, and Campylobacter. Other important bacterial pathogens include Escherichia coli, Vibrio parahaemolyticus, and Yersinia enterocolitica. Each of these pathogens has unique life cycle and virulence characteristics. The various causes of acute bacterial diarrhea are usually not distinguishable clinically, and diagnosis requires isolation of the organism on stool culture.

CASE 8-1

A 52-year-old woman with rheumatoid arthritis for 24 years was admitted to the hospital with complaints of fever and diarrhea for the preceding 3 days.

One month earlier she had been hospitalized for neck surgery. She was doing well in a rehabilitation hospital until 3 days before admission, when she developed a fever of 38.9°C associated with shaking chills and persistent severe watery diarrhea (25–30 bowel movements daily). One day before admission, she noted abdominal cramps, nausea, vomiting, and anorexia. The rehabilitation nurse found the woman’s blood pressure to be 70/50 mmHg, and referred her to the emergency ...

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