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Flashcards in Travel Associated Illnesses Deck (79)
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1

Describe the structure of Vibrios

Gram -
Comma Shaped
Polar Flagellum

2

How does the DNA of vibrios appear?

2 circular chromosomes

3

Vibrio pH happy place?

Highly alkali tolerent, but acid sensitive

4

How do vibrio feel about salinity?

Halotolerant, some halophilic

5

How are Vibrio cholerae classified?

Capsule, Biotypes, Serotypes

6

Disease state Vibrio cholerae has what capsule type?

O1 (no capsule)

7

Disease state Vibrio cholerae has what biotypes?

Classical
El Tor

8

What serotypes are associated with both biotypes? With One?

Both -- Ogawa, Inaba
Only El Tor -- O139

9

What medication is prone to promote Vibrio cholerae growth?

Antacid
Normally 10^6 needed, with AA only 10^3

10

Vibrio cholerae presents in what part of the body?

Small Intestine

11

Clinical presentation of Vibrio cholerae infection?

1-4 day incubation
Nausea, Vomiting, 1-2 loose stools
Acute, Profuse diarrhea -- "Rice Water Stool"
No Pain, Fever

12

Describe the "Rice Water Stools" seen in Vibrio cholerae infection.

Contains lots of mucus
10^8 vibrios/mL
No Blood

13

How does Vibrio cholerae tend to become a fatal disease?

Dehydration and Electrolyte loss

14

Vibrio cholerae is distributed where?

Around the world in water supplies via copepods

15

Hosts of Vibrio cholerae?

Only humans

16

What do we know about chronic Vibrio cholerae?

Very rare
"Cholera Delores"

17

Explain the pathogenesis of Vibrio cholerae.

Fibriae bind gut epithelium
AB5 Toxin expressed (Toxin/Pilus regulated by riboswitch)
B binds to receptor ganglioside G-m1 of epithelial cells
A-A's SS bond is reduced
A1 uses NAS to ADP-Ribosylate a Gs Protein

18

How does ADP-ribosylating a Gs protein influence host function?

Activates adenylyl cyclase
Increased cAMP causes ion secretion into gut
Water follows ions

19

Relationship between pertussis and cholera?

Similar mechanism
Per. blocks the inhibitor
Cholera locks in active state

20

Explain how the Vibrio cholerae riboswitch works

The switch weakly blocks the genes for toxin and pilus at low temperatures (ocean). When moved to higher temperatures (stomach), unstable base pairings fall apart, allowing transcription of the toxin and pilus

21

Most important component of treatment for Vibrio cholerae?

Rehydration and Electrolyte Replacement

22

An Oral Rehydration Salts (ORS) formula contains...

NaCl (3.5g/L)
KCl (1.5g/L)
NaHCO3 (2.5g/L)
Glucose (20g/L)

23

What medicinal treatment might be used for Vibrio cholerae?

Doxycycline can limit shedding, but can't stop the diarrhea

24

Describe Vibrio cholerae vaccines.

not very effective -- about 6 months
Use heat-killed O1 Classical Strain
Few doses available, used in outbreaks

25

Clinical presentation of Vibrio parahemolyticus

- 12-24 hour incubation
- Nausea, vomiting, watery-bloody diarrhea, maybe gastroenteritis

26

Where can Vibrio parahemolyticus be found? How is it typically spread?

Worldwide in Oceans
Raw/Undercooked Seafood

27

Pathogenesis of Vibrio parahemolyticus?

Biofilms
Type 3 and 6 Secretion Systems
Hemolytic/Cytotoxic Enterotoxin

28

How is Vibrio parahemolyticus treated?

Rehydration and electrolyte replacement
Doxycycline if necessary

29

Typical origin of Vibrio vulnificus infection?

Infected would from handling contaminated seafood
Bacteremia from eating raw oysters

30

Symptoms of Vibrio vulnificus infection?

Infected wounds from handling
Within hours, cellulitis and necrosis
Eventual liver damage
50% Fatal

31

What is cellulitis?

Inflammation of subcutaneous connective tissue

32

Vibrio vulnificus is always associated with contaminated ________ or _______.

Seawater or Seafood

33

Vibrio vulnificus has foci in what three US states?

TX
LA
AL

34

Describe the pathogenesis of Vibrio vulnificus

Antiphagocytotic capsule prevents control
Necrotizing cytotoxin release

35

What do you do if you suspect a patient has Vibrio vulnificus infection?

Doxycycline immediately
Takes 18 hours to get culture -- too late.

36

Describe the structure of campylobacter

G-
Curved, Helical, or Gul-Winged
Polar Flagella

37

What oxygen tolerance is campylobacter?

Microaerophile

38

How can you differentiate different campylobacter species?

Growth temperature

39

Temperature campylobacter jejuni can grow in?

42C, but not 25C

40

Clinical presentation of Campylobacter jejuni infection?

Abdominal Pain, Cramps, Fever
Very Bloody Diarrhea (Sometimes Blood Red)
May invade bloodstream and cause enteric fever in IC

41

Campylobacter jejuni is a disease of what part of the body?

Large Intestine

42

Secondary concern that may arise 1-4 weeks after Campylobacter jejuni infection?

Guillain-Barre syndrome

43

What is Guillain-Barre Syndrome?

A demyelinating neural disease
Causes Progressive flaccid paralysis
Causes by molecular mimicry/autoantibodies to G-M1

44

Campylobacter jejuni is primarily spread through what two methods?

Fecal-Oral Route
Contaminated Poultry and Milk

45

When do people tend to get Campylobacter jejuni in the US?

Summer

46

Who is most prone to suffer from Campylobacter jejuni ?

Infants and Young Adults

47

Top two bacterial causes of gastroenteritis?

Salmonella
Campylobacter jejuni

48

Campylobacter jejuni pathogenesis?

Inflammatory enterotoxin
Bacteremia indicates invasive potential

49

How is Campylobacter jejuni treated?

Rehydration therapy
Tetracycline, Quinolones, Clarithromycin if systemic infections

50

What temperature does Campylobacter fetus grow at?

Grows at 25C, but not at 42C

51

Clinical presentation of Campylobacter fetus?

Systemic infections, septicemia

52

How is Campylobacter fetus typically acquired?

Eating contaminated/Undercooked Beef

53

Who is most susceptible to Campylobacter fetus?

Elderly, Ill, IC

54

Pathogenesis of Campylobacter fetus?

S-layer protein inhibits complement fixation --> Less Phagocytosis

55

How is Campylobacter fetus controlled?

Tetracyclines, Macrolides, and Quinolones

56

Describe the Helicobacter pylori organizm structure.

Gram-
Spirillum (Lazy S)

57

Oxygen sensitivity of Helicobacter pylori?

Microaerophile

58

Helicobacter pylori produces huge amounts of ______

Urease
Detectable within minutes-hours

59

Is Helicobacter pylori infection typically acute or chronic?

Chronic

60

Helicobacter pylori colonizes where? How?

Gastric Mucosa esp. antrum
via Lewis Blood Group Adhesin

61

Helicobacter pylori is associates with what two pathologies?

Gastric/Duodenal Ulcers
Gastric Adenocarcinoma

62

How is Helicobacter pylori detected?

Serological Test
Gram Stain/Culture of Gastric Biopsy
Urea Breath Test

63

Which test for Helicobacter pylori is most effective?

Urea Breath Test

64

How does a Urea Breath Test work?

C14 Urea is fed, detection of 14-CO2 in breath indicates urease activity of the stomach

65

___% of people are Helicobacter pylori carriers

Approx. 50%

66

Helicobacter pylori infection is most commonly seen in which patients?

Middle-aged and older

67

What may mask Helicobacter pylori infection?

Long-term proton pump inhibitors seen in GERD patients

68

Helicobacter pylori is heavily correlated with a particular _____ allele?

TLR1

69

Describe the pathogenesis of Helicobacter pylori.

- Bind to base of gastric mucosal cells (pH=7.4)
- Bind Lewis Antigen
- Huge amounts of urease buffer pH
- Produce VacA (Vacuolating Toxin)

70

Helicobacter pylori is especially prevalent in people with Type __ Blood.

O
Lewis Antigen = O Blood group Antigen

71

How does urease activity buffer pH in the stomach?

Forms NH3 from Urea

72

Effects of vacuolating toxin (VacA)

- Activated by stomach acid
- binds to lipid rafts of gastric epithelium
- Inserts into cell as selective anion channel
- Extensive vacuolation of epithelial cells and urea release while inhibiting immune response

73

Ulcer associated strains of Helicobacter pylori also produce what toxin...

Cytotoxin (CagA)

74

CagA is secreted by...
It has what primary effect? What potential secondary effect?

Type 4 secretion system
Induced apoptosis of host cells
It may be an oncoprotein

75

Production of VacA and CagA virulence factors of Helicobacter pylori is enhanced by ______.

Salt

76

How are Helicobacter pylori ulcers treated?

Bismuth subsalicylate

77

How is Helicobacter pylori infection treated?

Tetracycline (or)
Macrolide+Metronidazole

78

How is Helicobacter pylori acid treated?

PPI

79

Why is bicarbonate alone an ineffective treatment for stomach ulcers?

It allos Helicobacter pylori to spread