Lecture 16 and 17: GI Infections (!) Flashcards by Katlyn Heneghan

Which family of gram (-) facultative, anaerobic, rod-shaped bacteria are commonly found in the GI?

Enterobacteria

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Three ways the GI infections can be transmitted?

Fecal oral
Fomites
Food and water borne

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What’s the difference between Diarrhea and Dysentery–both of which are symptoms of GI infections?

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True or False: C. perfringes, B. cereus, and S. aureus are associated with food BORNE DIARRHEAS

True

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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

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C. dif and EHEC cause infection by adherence to ___ and release of toxin resulting in destruction of ___ or ___

intestinal mucosa
brush border/mucosa

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___ 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

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Which three pathogens cause diarrheal disease via: mucosal translocation + proliferation within lamina propria and lymph nodes?

Salmonella
C. jejuni
Yersinia enterocolitica

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Which two viruses can cause infection + destruction of enterocytes, resulting in osmotic diarrhea?

Rotavirus
Norwalk Virus

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Which pathogen causes Gastritis?

H. pylori

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H. pylori is…
- Gram (+) or (-)?
- Shape?
- Acid Intolerant/Tolerant?

Gram (-)
Curved Rod
Motile
Acid Tolerant
Microaerophilic
Non-invasive

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Which enzyme does H. pylori have that permits it to be acid tolerant?

Urease

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___: 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)

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___ 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)

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Clinical significance of Urease?

Degrades Urea to Ammonia and Bicarbonate

NH3 raises stomach acid, making it more basic, so that H. pylori can grow!

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How do diagnose H. pylori?

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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

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True or False: ETEC/E.coli are leading cause of Traveler’s Diarrhea

True

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Features of E. Coli?
- Gram (+)/(-)
- Shape
- Aerobe? Anaerobe?
- Coliform?

E.coli
- Gram (-)
- Rod
- Facultative anaerobe
- Coliform: ferments lactose, produces gas + acid

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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

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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

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True or False: E.coli is lactose positive (+)

True

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___ 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

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True or False: V. cholerae are halophilic, non-invasive, gram negative curved rods

True

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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)?

1. S. aureus 2. Bacillus cereus 3. 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)?

1. Abx don't help 2. No RBC/WBC in stool 3. Cause: inadequate cooking, holding temp 4. 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

Which form of entertoxin, produced by Bacillus cereus, functions by stimulating adenylate cyclase (much like ETEC and CT)? A. Heat Stable (vomit) B. Heat Labile (diarrheal)

B. Heat Labile (diarrheal)

Which of the following anaerobic, gram (+), spore forming rods may be found in meat, poultry???? A. S. aureus B. Bacillus cereus C. C. perfringens

C. C. perfringens

What are two features of the entertoxin of Clostridium perfringes? A. Heat labile; acid labile B. Heat stable; acid labile C. Heat labile; base labile

A. Heat labile; acid labile

The enterotoxin made by C. perfringens (type A) functions by inhibiting ___ and ____ ion absorption

glucose; chloride

True or False: C. perfringens proliferates in the small intestines, which leads to entertoxin production, which produces s/s

True

How do you dx C. perfringens?

Detect spores in food or feces

What is an example of a Shiga-like/Verotoxin-toxin (STEC/VTEC) E.coli?

Enterohemorrhagic E.coli (EHEC, O157:H7) Note: O157:H7 = sorbitol negative fermenter (therefore: white)

True or False: EHEC and STEC/VTEC are associated with diarrheas accompanied by a fever

False - w/ or w/o fever

Virulence factor used by Enterohemorrhagic E.coli? A. Pili B. Shiga-like toxin C. Sorbital toxin

B. Shiga-like toxin (aka: verocytotoxin)

What are two effects of Shiga toxin?

1) GI Bleeds - hemorrhagic colitis 2) Hemolytic Uremic Syndromes - HUS

____: A triad that consists of hemolytic anemia + acute kidney failures + low platelet count A. HUS B. Hemorrhagic Colitis

A. Hemolytic Uremic Syndromes (HUS)

True or False: ETEC is a gram negative bacilli - most common serotype is O157:H7

False - EHEC

Why is STEC/EHEC able to be spread person to person? A. Poor hygiene and low dose organism B. Poor hygiene and high dose organism

A. Poor hygiene and low dose organism

True or False: Raw milk or apple juice could lead to STEC/EHEC

True

Two virulence factors used by STEC/EHEC?

1. Pilli (adherence in small intestines) 2. Stx (toxemia)

True or False: HUS is a bacteremia - not a toxemia

False - it is a TOXEMIA not a bacteriemia!

Are abx's an effective tx for STEC/EHEC?

No! They can increase amount of toxin produced, leading to poor outcomes

Stx of the EHEC binds to the ___ receptors, which can be found in a renal and gut endothelial cells A. Gb1 B. Gb2 C. Gb3

C. Gb3

Diagnosing STEC/EHEC?

C. dif and Clostridioides difficile-associated disease (CDAD) are associated with diarrheas that present: A. without a fever B. without or with fever C. with a fever

C. with a fever

___: Inflammation of large intestine

Colitis

___ is a gram (+), anaerobic rod, spore-form, that mostly has toxigenic strains

C. dif

C. dif can produce one or both of its toxins (Toxin _ or _) How do these toxins function?

Toxin A/B - Function as cytotoxins , disrupt protein synthesis within host cells

What are two pre-disposing factors to acquiring C. dif?

1. Hospitalization 2. Abx therapy

True or False: People on antacids or PPI have greater chance of developing C. Dif

True

True or False: C. Dif should be suspected in any patient with diarrhea who has received abx within the past two months/who have had diarrhea began 72 hrs or more after hospitalization

True

Febrile, Invasive Diarrheal Agents (Bacillary Dysentary) is associated with which pathogen?

Shigella

True or False: Shigella is a facultative, intracellular gram negative rod, non-motile. It is a lactose fermenter.

False - it is NOT a lactose fermenter (non coliform)

Bacillary dysentery (enterocolitis) --inflammation of small intestine and colon--is a clinical manifestation of ___

Shigella

How is Shigella transmitted?

1) Oral Fecal 2) Contaminated food

True or False: Shigella has very high infectious dose

False - very low infectious dose

How is Shigella classified?

By O antigen (serogroups)

S. dysenteriae, which is associated with HUS due to shiga toxin production, belongs to: A. Group A B. Group B C. Group C D. Group D

A. Group A

Taxonomy of Shigella?

True or False: Sheep and cows are the sole reservoir/host of Shigella

False - humans are sole reservoir/host

What is the most communicable bacterial diarrheal agent?

Shigella

What causes the inflammation, bleeding, abscess formation, and sloughing off of cells, as seen in Shigella?

Immune response

True or False: Shigella goes to the small intestines (diarrhea) then colon, where it escapes phagocytosed by macrophages

True

Shigella Virulence summary?

Which three pathogens are febrile, invasive diarrheal agents?

1. C. jejuni 2. Yersinia 3. Salmonella

What three features do (C. jejuni, Yersinia, Salmonella -- all of which are febrile, invasive diarrheal agents) have in common?

1. Gram (-) and non-lactose fermenting 2. Zoonosis 3. Invasive (can cause bacteremia)

True or False: Of C. jejuni, Yersinia, Salmonella -- only Yersinia and C. jejuni can survive in macrophages (facultative intracellular)

False - Yersinia and Salmonella can survive in macrophages but not C. jejuni

If a patient is infected with either: C. jejuni, Yersinia, or Salmonella and has a fever, what test should be done?

Blood culture to dx febrile, invasive diarrheal agents

___ is a gram (-) , oxidase (+) comma shaped motile rod that is NF in GIT of dogs, livestock A. C. jejuni B. Yersinia C. Salmonella

A. C. jejuni

True or False: The virulence factor LT of C. jejuni is ~ to ETEC/CT

True

True or False: C. jejuni can be transmitted via raw milk, undercooked chicken and is a high dose organism. Person to person spread is not usual.

False - it is low dose organism

True or False: C. jejuni is a intracellular pathogen that can cause inflammatory enteritis

False - extracellular pathogen that can cause inflammatory enteritis

How can you dx C. jejuni?

Look for WBC in stool

Which pathogen is an important cause of pseudoappendicitis?

Yersinia - small motile rods - safety pin

What are two ways to transmit Yersinia?

1. blood transfusion 2. food - milk - meat (canned)

Yersinia penetrates epithelial lining, specifically ___ and __. Where does it live?

Ileum + Colon Lives: lymphoid tissue

For yersinia, the ___ render killing by macrophage

OMP's

True or False: Yersinia enterotoxin is similar to ST of ETEC

True

Dx yersinia?

Special media + cold enrichment

True or False: Salmonella is a non-lactose, fermenting, motile, gram (-) rod - non-coliform

True

True or False: S. typhi causes typhoid (enter) fever

True

True or False: Salmonella is a high dose organism that usually has animals as its reservoir -- except in case of S. typhi (human host adapted)

True

Can salmonella survive in macrophages or disseminate via circulation?

Yes - can do both

Salmonella invades mucosa of which two organs?

Small Intestine and colon

How does Salmonella result in diarrhea? inflammation?

Diarrhea = stimulates fluid secretion Inflammation = penetrates epithelial cells to lamina propria

True or False: Salmonella can cause toxemia

True

True or False: Shigella is lactose negative while E.coli is lactose positive

True

Lecture 16 and 17: GI Infections (!) Flashcards

(102 cards)