1. Microbiology: A Systems Approach
PowerPoint to accompany
Microbiology: A Systems Approach
Cowan/Talaro
Chapter 22
Infectious Diseases Affecting the Gastrointestinal Tract
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2. Chapter 22
Topics
- Defenses
- Diseases

3. Defenses
Gastrointestinal tract
Normal flora
Protection

4. Gastrointestinal tract
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus

5. The main sections of the gastrointestinal tract.
Fig Major organs of the digestive system.

6. Normal flora Numerous species present Oral cavity
Bacteria
Fungi
Protozoa
Oral cavity
more than 550 species of bacteria
Stomach and small intestine
sparsely populated
Large intestine
more than 1011 per gram of contents

7. Protection Intestinal surfaces - layer of mucus Secretory IgA
Muscular walls (peristalsis)
Saliva
Stomach acid
Bile
Gut-associated lymphoid tissue (GALT)
Commensal or normal flora

8. Diseases Tooth and gum infections Mumps Gastritis and ulcers
Acute Infectious Diarrhea
Acute diarrhea with vomiting
Chronic diarrhea
Hepatitis
Helminthic intestinal infections
Liver and intestinal disease
Muscle and Neurological Symptoms
Liver disease

9. Tooth and gum infections
Dental caries
Periodontal diseases

10. Dental caries Bacterial infection Most common infection
Dissolution of solid tooth surface
Carbohydrates are fermented by bacteria and produce acids

11. A cross section of a tooth showing all the major structures associated with the crown and root.
Fig The anatomy of a tooth.

12. The different stages of plaque development, and the degrees of cariogenesis.
Fig stages in plaque development and cariogenesis.

13. Vegetable dye staining tablets enables macroscopic detection of plaque, while microscopic detection by SEM reveals a mixed bacterial aggregate.
Fig The macroscopic and microscopic appearance
of plaque.

14. Features of dental caries.
Checkpoint 22.1 Dental caries

15. Periodontal diseases Periodontitis
Necrotizing ulcerative gingivitis and periodontitis

16. Periodontitis Communities of different bacterial species
Gingivitus – early infection
Periodontitis – late or more serious infection
Plaque
Caculus

17. The stages involved in the formation of periodontitis.
Fig Stages in soft-tissue infection, gingivitis, and
Peroidontitis.

18. A radiograph of teeth showing calculus, caries, and bone destruction.
Fig The nature of calculus.

19. Necrotizing ulcerative gingivitis and periodontitis
Community of different bacterial species
Severe condition
Synergistic
At risk - poor hygiene, AIDS patients, diabetes, smoking

20. Features of periodontal diseases.
Checkpoint 22.2 Periodontal diseases

21. Mumps Viral infection Classic gopherlike swelling of the cheeks
Humans are exclusive natural host
Parotitis
Syncytium
Vaccine
Complications

22. The classic swelling of the cheeks or parotitis.
Fig The external appearance of swollen parotid glands in
Mumps.

23. Paramyxoviruses infect host cells, cause multinucleated cells or syncytia, which enable viruses to pass from an infected cell to noninfected cells.
Fig The effects of paramyxoviruses.

24. Features of mumps.
Checkpoint 22.3 mumps

25. Gastritis and gastric ulcers
Bacterial infection
Pain and lesions (peptic ulcers) in the abdomen
Common for blood type O individuals
Bacteria neutralizes stomach acid environment
Immune response damages epithelium
Possibly zoonotic

26. An endoscope is used to visualize the lesions caused by Helicobacter pylori, causative agent of peptic ulcers.
Fig endoscopy

27. Acute infectious diarrhea
Bacterial infection
Common nonbacterial infection
HKO antigens
Common among population – particular day care centers
Developing countries – serious health effects, fatal
In the U.S., 1/3 due to contaminated food

28. HKO antigens H = flagellar antigen K= capsular antigen
O= cell wall antigen
Ex. E. coli O157:H7

29. Bacterial Salmonella Shigella Shiga-toxin producing Escherichia coli
Non-shiga-toxin E. coli
Campylobacter
Yersinia
Clostridium difficile
Vibrio cholerae

30. Salmonella Contaminated animal products Salmonellosis - mild
Typhoid fever – severe
Normal flora in animals

31. Cases of typhoid fever and salmonelloses.
Fig Data on the prevalence of typhoid fever and
other salmonelloses

32. Shigella Primarily a human parasite Infects the large intestine
No perforation of intestine
Dysentery
Exotoxin (shiga-toxin)
Enterotoxin

33. Infection of the large intestine by Shigella dysenteriae.
Fig The appearance of the large intestional mucosa
In Shigella dysentery.

34. Shiga-toxin (E. coli) O157:H7 Enterohemorrhagic E. coli (EHEC)
Serious manifestations – hemolytic uremic syndrome, neurologic symptoms
Shiga-toxin gene present on bacteriophage genome
Type III secretion system

35. The Type III secretion is a complex bridge formed by the bacteria, enabling binding to the host cell, thereby allowing the bacteria to insert its products in the host cell.
Fig Type III secretion system.

36. Non-shiga-toxin (E. coli)
Enterotoxigenic – traveler’s diarrhea
Enteroinvasive – no exotoxin
Enteropathogenic – similar to EHEC
Enteroaggregative – chronic diarrhea

37. Campylobacter Most common bacterial cause of diarrhea
Related to Guillain-Barre syndrome (GBS) – paralysis

38. Campylobacter jejuni has a unique S-shaped and spiral morphology, and is closely related to H. pylori.
Fig Scanning micrograph of Campylobacter jejuni,
Showing comma, S, and spiral forms.

39. Yersinia High degree of abdominal pain Mistaken for appendicitis
Infects the small intestine
Some can affect the lymphatic system (intracellular)

40. Clostridium difficile
Pseudomembranous colitis or antibiotic associated colitis
Capable of superinfecting the large intestine due to drug treatments
Enterotoxins

41. A mild and more severe case of antibiotic-associated colitis.
Fig Antibiotic-associated colitis.

42. Vibrio cholerae Cholera Unique O and H antigens
Cholera toxin (CT) – A-B toxin
Bacteria never enter host cells
Heavy lost of fluid “rice-water stool”
Untreated cases can be fatal

43. Vibrio cholerae has a unique curved shaped and single polar flagellum.
Fig Vibrio cholerae

44. Common nonbacterial
Cryptosporidium
Rotavirus

45. Cryptosporidium Protozoan infection Zoonotic Oocysts Intracellular
AIDS patients are at risk
Associated with fresh water outbreaks

46. A SEM of Cryptosporidium shows attachment to the intestinal epithelium, prior to intracellular invasion.
Fig Scanning electron micrograph of Cryptosporidium

47. Acid-fast staining enables oocysts to be identified, as they stain red or purple.
Fig Acid-fast stain in Cryptosporidium

48. Rotavirus Responsible for most morbidity and mortality from diarrhea
Babies lacking maternal antibodies are at risk
Unique morphological appearance

49. A feces sample containing Rotavirus, which has a unique “spoked-wheel” appearance.
Fig Rotavirus visible in a sample of feces from
A child with gastroenteritis.

50. Features of acute diarrhea.
Checkpoint 22.5 Acute diarrhea

51. Acute diarrhea with vomiting
Food poisoning - toxin
Staphylococcus aureus
Bacillus cereus
Clostridium perfringens

52. Features of acute diarrhea with vomiting.
Checkpoint 22.6 Acute diarrhea with vomiting

53. Chronic diarrhea Enteroaggregative (EAEC) E. coli
Cyclospora cayetanensis
Giardia lamblia
Entamoeba histolytica

54. EAEC E. coli can be identified by its ability to adhere to human cells in aggregates.
Fig Enteroaggregative E. coli adhering to epithelial cells.

55. The protozoan Cyclospora can be identified by the acid-fast stain, in which large cysts stain pink to red and have a wrinkled outer wall.
Fig An acid-fast stain of Cyclospora in a human
Fecal sample.

56. The protozoan Giardia is typically transmitted by its cysts, which eventually germinates into the trophozoite and damages the jejunum.
Fig The “face” of a Giardia lamblia trophozoite.

57. Entamoeba histolytica have different cellular forms, which includes a trophozoite that contains a karyosome and hosts cells (rbc) and bacteria, and a mature cyst which undergoes excystment.
Fig Cellular forms of Entamoeba hystolytic

58. Features of chronic diarrhea.
Checkpoint 22.7 Chronic diarrhea.

59. Hepatitis Viral infection Inflammation of the liver Jaundice
Hepatitis A
Hepatitis B
Hepatitis C
Inflammation of the liver
Jaundice
Noninfectious conditions can cause hepatitis

60. Hepatitis A virus Low virulence Poor hygiene – fecal-oral
Developed countries – adult
Developing countries- child
Vaccine
Similar to Hepatitis E – pregnant women are at risk

61. Hepatitis B virus High virulence Serum hepatitis Cirrhosis
Dane particle
S antigen
Chronic infection – particularly children
Associated with hepatocellular carcinoma

62. Hepatitis C virus “Silent epidemic” – symptoms not seen for years
Blood contact
Chronic
No vaccine
Liver transplants
Associated with cancer

63. Features of Hepatitis.
Checkpoint 22.8 Hepatitis

64. Helminthic intestinal infections
Various parasites
Small roundworms to large tapeworms
Eosinophilia
Four major life cycles
Definitive host
Intermediate host
Antihelminthic therapy
Intestinal distress
Intestinal distress with migratory symptoms

65. Examples of some antihelminthic therapeutic agents and their effects.
Table 22.1 Antihelminthic therapeutic agents and their effects.

66. Examples of four basic helminth life and transmission cycles.
Fig Four basic helminth life and transmission cycles.

67. An example of the unique morphology of tapeworms, which includes a sucker and hooklets, and the extensive length.
Fig Tapeworm characteristics.

68. Features of intestinal distress.
Checkpoint 22.9 Intestinal distress.

69. Migration of some helminths is due to their hook or oral cutting plates which anchors it to the host intestinal villi.
Fig Cutting teeth on the mouths

70. An example of the migratory nature of Strongyloides.
Fig A patient with disseminated
Strongyloides infection.

71. Features of intestinal distress plus migratory symptoms.
Checkpoint Intestinal distress plus migratory symptoms.

72. Liver and intestinal disease
Helminth infection
Begins in the intestine and migrates to the liver
Liver flukes
Definitive and intermediate host

73. An example of the sheep live fluke Fasciola hepatica.
Fig Fasciola heepatica, the sheep liver fluke

74. Features of liver and intestinal diseases.
Checkpoint Liver and intestinal disease.

75. Muscle and neurological disease
Protozoan infection
Trichinosis
Life spent entirely in mammal host
Common to the U.S. and Europe
Pork, bear meat

76. Features of muscle and neurological symptoms.
Checkpoint Muscle and neurological symptoms

77. Liver disease Helminth infection Schistosomiasis Blood flukes
Evades host immune system by coating itself with proteins from the host bloodstream
Endemic

78. The life of Schistosoma is complex.
Fig Stages in the life cycle of Schistosoma.

79. Features of liver disease caused by blood flukes.
Checkpoint Liver disease

80. Summary of the diseases in the gastrointestinal tract.
Taxomonic organization of microorganisms causing
Disease in the GI tract.

81. Infectious Diseases Affecting the Gastrointestinal Tract.
Fig. 22.p730