Vibrio, Campylobacter, Helicobacter

Question 1

What virulence factors of V. cholerae helps the organism adhere to the intestinal tract and causes the body to dump water into the intestinal lumen, which may lead to dehydration and death?

Answer 1

• Adhesins
  
  • Single polar flagella
  • Toxin co-regulated pili (TCP Type IV)
  • Hemagglutinin protease

Question 2

Cholera toxin binds to _____ found on many different cell types.

Answer 2

Ganglioside

Question 3

How does Cholera toxin cause net excretion of electrolytes then water from cells?

Answer 3

• A1 subunit ADP ribosylates protein Gsa →
  
  • ​Locks adenylyl cyclase into perpetual on cycle →
  • Increase cAMP →
  • Net excretion

Question 4

T/F Cholera toxin is enoded in V. cholerae’s chromosome

Answer 4

FALSE

Cholera toxin is phage encoded

Question 5

V. cholerae _____ (a virulence factor) directly correlates with its virulence. Its presence indicates more severe symptoms. What serological group of this factor causes the majority of disease?

Answer 5

• O1 antigen
• Serogroup Inaba (El Tor) causes majority of disease

Question 6

What is the only non-O1 derivative that does not produce milder illness by V. cholerae?

Answer 6

O139

Question 7

The serious form of Cholera is acquired by _____

Answer 7

Consumption of contaminated seafood

Question 8

Patients with cholera produce massive amounts (10-15L) of stool *without fever* that has a characteristic _____ appearance

Answer 8

Rice water stool

Question 9

T/F V. cholerae invades host cells

Answer 9

FALSE

No invasion → no direct tissue damage → no fever

Question 10

V. cholerae is sensitive to _____ and _____

Answer 10

• Drying
• Acidic pH
  
  • Pts. with achlorhydria or those taking antacids are more susceptible

Question 11

When cultured on ____ agar, V. cholerae grows as _____ colonies that ferment _____ and _____

Answer 11

• TCBS agar
• Grows as yellow colonies
• Ferment sucrose and citrate

Question 12

Upon gram staining, V. cholerae appear as _____

Answer 12

• Comma shaped gram negative rods
  
  • Look like seagulls in pairs

Question 13

What is the treatment for Cholera?

Answer 13

• IV fluid/electrolyte replacement
• Tetracycline
  
  • Reduces severity/length

Question 14

In contrast to V. cholerae, V. parahemolyticus _____ intestinal epithelium with _____

Answer 14

Invades with invasins

Question 15

In contrast to V. cholerae, the diarrhea caused by V. parahemolyticus is _____

Answer 15

Inflammatory (V. cholerae diarrhea is secretory)

Question 16

What is the name of the hemolysin produced by V. parahemolyticus?

Answer 16

Kanagawa toxin

Question 17

V. parahemolyticus is acquired via _____

Answer 17

Consumption of contaminated seafood

Question 18

In healthy individuals, V. parahemolyticus infection presents as a _____, but immunocompromised patients may develop _____

Answer 18

• Healthy: Self limiting diarrhea
• Immunocompromised: May develop septicemia

Question 19

How is infection by V. parahemolyticus treated?

Answer 19

• Fluid/electrolyte replacement
• Tetracycline

Question 20

Infection by V. vulnificus causes a severe _____ and is associated with _____

Answer 20

• Severe cellulitis (“Marsh Death”)
• Assd. w/ raw or undercooked seafood

Question 21

What are the four virulence factors of V. vulnificus?

Answer 21

• Acidic capsule - Makes phagocytosis difficult
• Exotoxin
• Proteases - Most serious, causes necrotizing cellulitis
• Siderophores - Hunt for iron, bring it back to organism

Question 22

What groups are at risk for V. vulnificus infection?

Answer 22

• Older males
• Pts. w/Liver disease or iron storage disease
• Classic exam question: Alcoholic shrimper/fisherman

Question 23

How is V. vulnificus ID’d clinically?

Answer 23

• Collect blood/wound exudates
  
  • Enrich for growth with alkaline peptone broth
• Culture on TCBS agar
  
  • Green colonies (vs. yellow V. cholerae colonies)

Question 24

How is V. vulnificus infection treated?

Answer 24

• Tetracyclines
• Fluoroquinolones
• If damage done: Debridement or amputation

Question 25

What organism is the leading cause of diarrhea in the US and developed world (besided Norovirus)

Answer 25

Campylobacter jejuni

Question 26

What adhesins are expressed by C. jejuni, allowing it to adhere to intestinal lining?

Answer 26

* CadF * PEB1

Question 27

T/F: C. jejuni is a microaerophile that grows at low temps (four degrees Celsius)

Answer 27

TRUE

Question 28

How is C. jejuni acquired?

Answer 28

* Eating/drinking contaminated foods and beverages * Unpasteurized milk, undercooked meats * Fecal-orally from pets * Dog feces

Question 29

T/F: Like V. cholerae, C. jejuni does not invade the intestinal epithelium

Answer 29

FALSE C. jejuni DOES invade and cause damage to the intestinal lining

Question 30

What three symptoms appear within 2-4 days after acquiring a C. jejuni infection?

Answer 30

* Little/no vomiting * Intense cramps * Inflammatory diarrhea * Lasts 1-2 weeks

Question 31

T/F C. jejuni infection follows a self-limiting course

Answer 31

TRUE

Question 32

Antibody to lipooligosaccharide cross-reating with host gangliosides (in myelin) results in the development of _____ 2-3 weeks after infection

Answer 32

Guillain-Barre Syndrome

Question 33

How is C. jejuni identified clinically?

Answer 33

* Enrich loose stool sample by incubating in cold storage * Requires microaerophilic environment * Culture on CAMPY blood agar * Contains selecting abx * Oxidase +, Gram -, curved organism

Question 34

Treatment for C. jejuni infection?

Answer 34

* Erythromycin or Ciprofloxacin * Reduces severity, does not eliminate symptoms

Question 35

The virulence factors of H. pylori destroy the protective layer of the stomach leading to \_\_\_\_\_

Answer 35

Further damage of stomach cells by acid leading to *ulcers*

Question 36

What virulence factor of H. pylori neutralizes stomach acid, providing a protective buffer for the organism?

Answer 36

* Urease * Converts urea to ammonia

Question 37

The natural mode of H. pylori transmission is most likely \_\_\_\_\_

Answer 37

Fecal-oral

Question 38

What virulence factor of H. pylori induces host cyclooxygenase, triggering apoptosis?

Answer 38

Vacuolating toxin (VacA)

Question 39

What is the most characteristic symptoms of H. pylori infection?

Answer 39

Gnawing or burning pain with an empty stomach that is less obvious when full (Less commonly: Nausea, vomiting, loss of appetite, anemia from blood loss)

Question 40

What cancers are linked to H. pylori infection?

Answer 40

Adenocarcinoma and MALT B-cell lymphoma

Question 41

How does H. pylori adhere to the stomach mucosa?

Answer 41

Via pili & glycocalyx

Question 42

What are the three B's of H. pylori clinical ID?

Answer 42

* Blood * Serology for Abs * Breath * Measures amount of radioactive CO2 * From urease converting tagged urea to CO2 + NH3 * Biopsy * Curly rod looking organism * *Urease test positive*

Question 43

What are the treatment options for H. pylori infection?

Answer 43

* Amoxicillin * Tetracycline * Metronidazole * Bismuth salts * Proton pump inhibitor