Unit 9.4: Diseases of the Gastrointestinal System
Outline
Part 1: Anatomy and Normal Microbiota of the Digestive System
Part 2: Bacterial Infections of the Digestive System
- Staphylococcal Food Poisoning
- Shigellosis (Bacillary Dysentery)
- Salmonellosis
- E. coli Infections
- Cholera
- Peptic Ulcers
- Clostridioides difficile
Learning Objectives
After reading the following, you should be able to:
- Describe the basic structure of the gastrointestinal system, including protective features and defenses.
- Describe any features that promote microbial growth and give one example of a bacterial species that is part of the normal flora.
- Describe any general features of infections of the gastrointestinal system.
- Describe staphylococcal food poisoning, including its causative organism and possible complications.
- Describe shigellosis, including its causative organism and possible complications.
- Describe salmonellosis, including its causative organism and possible complications.
- Describe E. coli infections and possible complications.
- Differentiate between EPEC and EHEC
- Describe cholera, including its causative organism and possible complications.
- Describe peptic ulcers, including their causative organism and possible complications.
- Describe C. difficile infections, including any possible complications.
- Describe hepatitis, including its causative organism and possible complications.
- Differentiate between HAV, HBV and HCV
- Describe giardiasis, including its causative organism and possible complications.
- For all the diseases in this section, describe mode of transmission, portal of entry, modes of detection (where discussed) and treatments (in general, e.g. antiviral medication, vaccine, etc)
Gastrointestinal (GI) diseases are so common that, unfortunately, most people have had first-hand experience with the unpleasant symptoms, such as diarrhea, vomiting, and abdominal discomfort. The causes of gastrointestinal illness can vary widely, but such diseases can be grouped into two categories: those caused by infection (the growth of a pathogen in the GI tract) or intoxication (the presence of a microbial toxin in the GI tract).
Foodborne pathogens like Escherichia coli O157:H7 are among the most common sources of gastrointestinal disease. Contaminated food and water have always posed a health risk for humans, but in today’s global economy, outbreaks can occur on a much larger scale. E. coli O157:H7 is a potentially deadly strain of E. coli with a history of contaminating meat and produce that are not properly processed. The source of an E. coli O157:H7 outbreak can be difficult to trace, especially if the contaminated food is processed in a foreign country. Once the source is identified, authorities may issue recalls of the contaminated food products, but by then there are typically numerous cases of food poisoning, some of them fatal.
Part 1: Anatomy and Normal Microbiota of the Digestive System
The human digestive system, or the gas