Chapter 20: Infectious Diseases Affecting the Gastrointestinal Tract Flashcards
GI Tract Defenses
- intestinal surfaces coated with layer of mucus
- IgA found on most surfaces
- peristalsis
- saliva
- lysozyme and lactoferrin
- stomach acid
- bile
- appendix
- GALT
GALT
- tonsils and adenoids in the oral cavity and pharynx
- small areas of lymphoid tissue in the esophagus
How does E. coli assist with digestion?
Synthesizes vitamin K
Which of the following types of organisms are not considered normal biota of the gastrointestinal system?
A.bacteria
B.archaea
C.fungi
D.protozoa
E.None of the choices is correct.
B. archaea
Causative agents of chronic diarrhea
- E. coli
- Cyclospora
- Giardia
- Entamoeba
Causative agents of food poisoning
- Staphylococcus aureus
- Bacillus cereus
- Clostridium perfringens
Causative agents of dental carries and periodontitis
- Streptococcus mutans
- Scardovia wiggsiae
Causative agent of mumps
Paramyxovirus
Causative agent of Salmonella
- S. enteritica
- other bacteria may cause also
Properties of Salmonella
- ferment glucose; Motile
- can survive outside the host in hospitable environments, fresh water and freezing temperatures
- resistant to chemicals
- Most strains come from animals
- Salmonella are normal intestinal biota in cattle, poultry, rodents, and reptiles
Signs and Symptoms of Salmonella
- Severe forms of salmonellosis can include
- elevated body temperatures
- septicemia
- Milder forms of salmonellosis
- Vomiting
- diarrhea
- mucosal irritation
- blood can appear in the stool
- death is infrequent except in debilitated
Illnesses caused by salmonella
- Typhoid fever
- caused by the typhi variant. Salmonella typhi infects humans exclusively
- Gastroenteritis
- caused by paratyphi, hirschfeldii,
and typhimurium
Salmonella’s virulence factors
- its ability to adhere effectively to gut mucosa
- endotoxin
Prevention and Treatment of Salmonella
- Avoid contact with bacteria
- trimethoprim-sulfamethoxazole (TS)
- when disease is severe
Salmonella has a high ID50, meaning…
A lot of organisms must be ingested for disease to result
Salmonella commonly found in
milk and eggs
Shigella bacteria characteristics
- gram-negative rods
- non motile
- non-spore-forming
- primarily human parasites, but can infect Apes
Signs and symptoms of Shigella
- Frequent, watery stools
- Fever
- Intense abdominal pain
- Nausea and vomiting are common
Dysentery
- diarrhea containing blood
- Mucus from the GI tract is also present in the stools
Virulence Factors of Shigella
- Shigella invades the villus cells of the large intestine rather than the small intestine
- Causes inflammatory response
- Enterotoxin