Microbiology - Vibrio, Campylobacter, Helicobacter - Rebecca Greenblatt Flashcards Preview

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Flashcards in Microbiology - Vibrio, Campylobacter, Helicobacter - Rebecca Greenblatt Deck (30):
1

Phlyogeny: vibrio cholera

gram negative rod;
oxidase positive
facultative anaerobe

2

What strains of vibrio cholera cause epidemic disease?

O1 and O139 - O cell wall antigen indicates pathogenicity

3

Transmission: Vibrio cholera

Fecal-oral;
Usually killed by stomach acid;
High IU

4

Virulence factor: Vibrio cholera

Mucinase to clear brush border, attach with toxin-coregulated pilus;
Growing bacteria secrete cholera toxin

5

What kind of toxin is cholera toxin?

Enterotoxin
AB subunit structure
B binds ganglioside receptor GM1 on intestinal lining

Toxin carried by lysogenic bacteriophage CTX

6

Persistent activation of adenylate cyclase leads to what in the pathogenesis of vibrio cholera?

Loss of water and ions;
no absorption by microvilli, only secretion from crypts;
Massive watery diarrhea

7

What are the complications of v. cholera?

Acidosis and hypokalemia from severe dehydration

loss of bicarbonate and K

8

Culture V. cholera on:

Salt agar ("halophile");
Buffered media (ox pos, ferments sucrose);
acid-rxn on triple sugar iron agar

9

Phylogeny: V. Parahaemolyticus

Gram neg
Oxidase pos
Curved and motile
Halophile

more common than V. vulnificus

10

How does V. parahaemolyticus usually present?

Mild gastroenteritis

found in shellfish

11

Phylogeny: Vibrio vulnificus

Gram neg
Oxidase pos
Curved and motile
some are encapsulated
Halophile
Produces siderophores - infection exacerbated by iron overload

Warm ocean water

12

Wounds contaminated by shellfish or ocean water causes:

Severe cellulitis if contaminated by V. Vulnificus
Septicemia with hemorrhagic bullae

13

What toxins are used by V. Vulnificus?

Protease exotoxin;
Hemolysin

14

Phylogeny: Campylobacter

Gram neg
Comma or S shaped
Ox pos
Cat pos
*microaerophilic*

15

Transmission: Campylobacter

fecal-oral (raw milk, undercooked chicken), sexual contact, sick pets (puppies)

16

Reservoir: Campylobacter

guts of domestic animals: ~100% poultry asymptomatically infected

17

What is the IU for Campylobacter?

About 500 IU (very low)

18

Symptoms: Campylobactor

Bloody diarrhea with pus, crypt ulcerations (can have watery diarrhea also)
About 3-5 days
Self-limited but complications possible

19

What kind of Campylobacter is strongly predisposing for Guillan-Barre syndrome?

Campylobacter jejuni

Serotype O:19 antigenic cross-reactivity with neural glycosphingolipids

20

What are two less common complications of C. jejuni?

Reactive arthritis;
HUS

21

Does Campylobacter use M cells to cross the intestinal wall?

No; attaches directly

T4SS also

22

How do you culture Campylobacter?

Stool sample culture at high and low temp (growth fails at low temp)

23

"Seagull" appearance on microscopy is associated with what bug?

Campylobacter

24

Treat the immunocomprimised adult with Campylobacter infection with:

Azithromycin

25

Treat children with Campylobacter infection with:

Erithromycin

26

Phylogeny: H. Pylori

Gram negative rods
Curved
LPS
Strongly Urease pos

27

How can you tell a vibrio infection from a heliobacter infection?

Heliobacter can survive stomach acid

28

Virulence: H. pylori

Bacteria attach to mucus-secreting cells of stomach w/ flagella virulence factor;
Break down urea into ammonia w/ urease;
Ammonia **neutralizes stomach pH**, allowing bacterial growth and irritating stomach lining

29

What infiltrate is caused by H. pylori?

infiltrate by neutrophils, T and B lymphocytes, macrophages and mast cells

30

What is the old testing modality for H. Pylori?

Urea breath test - Swallow radiolabeled urea, exhale radiolabeled CO2