Lecture 16 and 17: GI Infections (!) Flashcards
Which family of gram (-) facultative, anaerobic, rod-shaped bacteria are commonly found in the GI?
Enterobacteria
Three ways the GI infections can be transmitted?
- Fecal oral
- Fomites
- Food and water borne
What’s the difference between Diarrhea and Dysentery–both of which are symptoms of GI infections?
True or False: C. perfringes, B. cereus, and S. aureus are associated with food BORNE DIARRHEAS
True
V. cholerae and ETEC cause infection by adherence to ___ and release of ___
A. enterocytes; toxoid
B. intestinal mucosa; toxoid
C. intestinal mucosa; toxin
C. intestinal mucosa; toxin
C. dif and EHEC cause infection by adherence to ___ and release of toxin resulting in destruction of ___ or ___
intestinal mucosa
brush border/mucosa
___ is the only pathogen to cause infection via mucosal invasion and proliferation within enterocytes
A. Salmonella
B. C. dif
C. EHEC
D. Campylobacter
E. Shigella
E. Shigella
Which three pathogens cause diarrheal disease via: mucosal translocation + proliferation within lamina propria and lymph nodes?
Salmonella
C. jejuni
Yersinia enterocolitica
Which two viruses can cause infection + destruction of enterocytes, resulting in osmotic diarrhea?
Rotavirus
Norwalk Virus
Which pathogen causes Gastritis?
H. pylori
H. pylori is…
- Gram (+) or (-)?
- Shape?
- Acid Intolerant/Tolerant?
- Gram (-)
- Curved Rod
- Motile
- Acid Tolerant
- Microaerophilic
- Non-invasive
Which enzyme does H. pylori have that permits it to be acid tolerant?
Urease
___: Most common virulence factor of H. pylori, which damages gastric epithelial cells by inducing vacuoles + is responsible for gastric ulcers (!!!)
A. Vacuolating Cytotoxin
(Vac A)
B. Cytotoxin Associated Gene A (CagA)
C. Urease
A. Vacuolating Cytotoxin
(Vac A)
___ is not found in all strains of H. pylori and increases virulence. Further, it induces inflammation + destruction of mucosa + is responsible for gastric cancer
A. Vacuolating Cytotoxin
(Vac A)
B. Cytotoxin Associated Gene A (CagA)
C. Urease
B. Cytotoxin Associated Gene A (CagA)
Clinical significance of Urease?
Degrades Urea to Ammonia and Bicarbonate
NH3 raises stomach acid, making it more basic, so that H. pylori can grow!
How do diagnose H. pylori?
Which two pathogens can cause watery diarrhea but no fever (afebrile)
A. ETEC
B. V. cholerae
C. E. coli
D. Cutibacterium acnes
A. ETEC (Enterotoxigenic E. coli)
B. V. cholerae
True or False: ETEC/E.coli are leading cause of Traveler’s Diarrhea
True
Features of E. Coli?
- Gram (+)/(-)
- Shape
- Aerobe? Anaerobe?
- Coliform?
E.coli
- Gram (-)
- Rod
- Facultative anaerobe
- Coliform: ferments lactose, produces gas + acid
ETEC (Enterotoxigenic E. coli) causes afebrile state + watery diarrhea by attaching to SMALL INTESTINES and secreting which two enterotoxins?
1) Heat Labile (LT): Antigenic, activates adenylyl cyclase and increases cAMP
2) Heat Stable (ST): Non-antigenic, activates guanylyl cyclase and increases cGMP
True or False: Both the toxins secreted by ETEC and the Cholera Toxin (similar to LT) cause mucosal cells to secrete fluid and electrolytes
True
True or False: E.coli is lactose positive (+)
True
___ is a high dose organism/pathogen that causes watery diarrhea without fever that uses saltwater or contaminated food (e.g shellfish) as a vehicle
A. E.coli
B. ETEC
C. V. cholerae
C. V. cholerae
True or False: V. cholerae are halophilic, non-invasive, gram negative curved rods
True
V. cholerae produces _____ toxin – which is similar to _____ of ETEC – and causes mucosal cells to secrete fluids + electrolytes. This secretion is responsible for disease manifestation
Cholera Toxin (CT);
Heat Labile (LT)
electrolytes and fluids
True or False: Heat Labile Toxin (LT) of ETEC is encoded on a bacteriophage
False - Cholera Toxin of V. cholerae is!
True or False: Cholera Toxin (CT) is an AB5 toxin that is heat-labile, just like Heat Labile Toxin (LT) of ___
ETEC
Which subunit of the cholera toxin binds to ganglioside (GM1) on the intestinal epithelial cells
A. Alpha
B. B subunit
C. A subunit
D. Beta subunit
B. B subunit
How do you diagnose V. cholera?
Which three pathogens are food borne diseases associated with Afebrile watery diarrhea (intoxication)?
- S. aureus
- Bacillus cereus
- Clostridium perfringens (Type A)
What are four features that are shared by: S. aureus, Bacillus cereus, and C. perfringens have in common (food borne pathogens - associated w/afebrile watery diarrhea)?
- Abx don’t help
- No RBC/WBC in stool
- Cause: inadequate cooking, holding temp
- Not transmissible
True or False: In the staphylococcal and emetic forms of Bacillus cereus, the food borne diseases are pre-formed in food
True
The diarrheal forms of ___ and ___ (type A) are associated with toxin released in gut from ingested bacteria – in food borne disease commonalities
C. perfringens (type A) and B.cereus
True or False: The emetic form of B. cereus is a toxin released in the gut from ingested bacteria while the diarrheal form is preformed in food
False
1) Emetic form of B. cereus = preformed in food
2) Diarrheal form of B. cereus = toxin release in gut from ingested bacteria
Features of S. aureus?
- Gram (+) or (-)
- Shape?
- Coagulase (+) or (-)
Gram (+)
Cocci
Coagulase (+)
What is the toxin produced by some S. aureus known as? Features?
SET (staph entertoxin)
- heat stable
- acute emetic and diarrheal disease when toxin consumed via foods
Which of the following pathogens may be found in processed meats, canned foots, potato salads, or boston cremes :c ????
A. S. aureus
B. Bacillus cereus
C. C. perfringens
A. S. aureus
True or False: When S. aureus produces its enterotoxin, it is ingested, absorbed in the gut, and acts on the vomiting center in the CNS
True
___ is a gram (+), aerobic, spore forming rod that can lead to food borne disease, particular if one eats potatoes, rice, or veggies
Bacillus cereus
Bacillus cereus produces two enterotoxins: a heat stable (emetic) form and a heat labile (diarrheal) form – which is preformed in food? which proliferates in small intestines?
Emetic form
- heat stable
- pre-formed in food
diarrheal form
- organism proliferates in small intestine => heat labile enterotoxin => s/s