Vibrio, Camphylobacter, Helicobacter

Question 1

Vibrio shape and genome

Answer 1

Gram negative

Comma shaped rod with a Polar Flagellum

2 circular chromosomes

Question 2

Vibrio are ____ tolerant and ______ -tolerant

Answer 2

alkali-tolerant

Halo-tolerant

Question 3

Vibrio can reside on _____. This allows….

Answer 3

Copepods

–> we can filter the copepods through a folded cloth

Question 4

Vibrio antigens (and types)

Answer 4

Strains share H antigens, but have different O antigens

2 of the O antigens cause cholera

Question 5

Vibrio are sensitive to…

Answer 5

acid

(pH less than 6)

Question 6

Two strains of vibrio cholerae

Answer 6

O1 and O139

O1 (no capsule) = causes the majority of outbreaks

O139 (polysaccharide capsule)

Question 7

Two biotypes of O1 V. cholerae

Answer 7

classical + El Tor

Question 8

Two serotypes of V. cholerae

Answer 8

Ogawa + Inaba

Question 9

V. cholerae - El Tor characteristics (3)

Answer 9

1. Polymixin resistant
2. produces hemolysin
3. LESS toxin is produced –> better colonization (less cytotoxicity)

Question 10

Classical O1 vibrio cholerae is responsible for…

Answer 10

6 pandemics

Question 11

V. cholerae requires ___________ to colonize

Answer 11

LARGE numbers of bacteria (10^6)

** This can be reduced to 10^3 if an antacid is being used

Question 12

V. cholerae is essentially a _____ disease

Answer 12

small intestine

Question 13

V. cholera timeline of symptoms

Answer 13

1. 1-4 days incubation
2. nausea, vomiting, 1-2 loose stools
3. 20L/day ricewater stool (contains high numbers of vibrios but no blood)

*no fever/pain

*dehydration and electrolyte loss causes circulatory collapse and death

Question 14

V. cholerae present in ________

Answer 14

water (especially estuarine water), carried by copepods

Question 15

V. cholerae hosts?

Answer 15

humans only natural host

Question 16

Vibrio spread via…

Answer 16

fecal-oral

Question 17

V. cholerae long-term carriers are ______

Answer 17

rare

Question 18

V. cholerae pathogenic factors

Answer 18

• Fimbriae bind to gut epithelium
• Toxin

Question 19

V. cholerae toxin:

• Genetics/structure?
• How does it function? (steps)

Answer 19

• AB5 toxin
  
  • expressed by ctxAB operon on PAI on chromosome 1
  • Toxin and pilus genes regulated by ToxT (temperature-sensitive riboswitch)
  • A is in two subunits joined by disulfide bond
  • B binds as pentamer to ganglioside Gm1 (epithelial cells)
• The Disulfide bond is reduced, and A1 uses NAD to ADP ribosylate a stimulatory G protein (G_s) = ACTIVATES adenyl cyclase, which increases cAMP-mediated ion secretion into the gut lumen (with water following)

Question 20

V. cholerae treatment and antibiotics

Answer 20

Oral rehydration Salts formula

Doxycycline can limit shedding but not diarrhea

• WHO recommends only use if more than 10% dehydrated
• CDC recommends one dose for all hospitalized cases
• AZITHROMYCIN for pregnant patients!

Question 21

V. cholerae vaccine?

Answer 21

(not very effective)

–3 oral vaccines using heat-killed O1 classical strain

(Dukoral, Shanchol, mORC-VAX)

Question 22

V. parahemolyticus is a ________ organism

Answer 22

halophilic

Question 23

V. parahemolyticus infection sequence

From where does someone get this infection?

Answer 23

Self limiting infection

nausea > watery > bloody (w/ or w/o gastroenteritis) > resolution in 1-4 days

Ocean waters, consumed in contaminated undercooked seafood

Question 24

V. parahemolyticus pahtogenic factors (3)

Answer 24

1. Biofilms
2. Type 3 and 6 secretion systems
3. Hemolytic/cytotoxic enterotoxin

Question 25

V. parahemolyticus control measures (Tx and antibiotics)

Answer 25

Rehydration Doxy if necessary

Question 26

V. vulnificus is a ______ organism

Answer 26

halophilic

Question 27

Where do you get V. vulnificus? What kind of infection does it cause?

Answer 27

* From handling contaminated seafood (shellfish).... Bacteremia from eating raw oysters * VERY rapid cellulitis and necrotic infection, eventual liver damage. 50% fatal

Question 28

V. vulnificus especially associated with \_\_\_\_\_\_. In the United States, endemic foci are in \_\_\_, \_\_\_,and \_\_\_\_

Answer 28

Oysters Texas, Louisiana, Alabama

Question 29

The two pathogenic factors for V. vulnificus

Answer 29

1. Antiphagocytic capsule 2. necrotizing cytotoxin

Question 30

V. vulnificus Treatment

Answer 30

**Doxy** right away! ---*Cipro if pregnant* DO NOT CULTURE -- it takes too long, will be too late by the time results come back

Question 31

Camphylobacter organism and shape

Answer 31

Gram negative Curved, helical, or gull-winged Polar flagella (sometimes bipolar)

Question 32

Two camphylobacters that cause infection, and their growth characteristics

Answer 32

jejuni = high temp fetus = low temp (much more serious infection)

Question 33

Camphylobacter organism is a \_\_\_\_\_\_\_\_\_\_\_

Answer 33

microaerophile

Question 34

C jejuni grows at \_\_\_\_\_\_. It requires ____ ingestion of ______ organisms to grow. It is a disease of the \_\_\_\_\_\_\_\_

Answer 34

42 degrees, but NOT at 25 degrees orally ingest 10^4 organisms disease of the large intestine

Question 35

C jejuni presentation

Answer 35

* Gastroenteritis - abdominal pain * Cramps, fever, VERY _bloody_ diarrhea (INVASIVE organism) * Self limiting within a week * May result in GBS because of Molecular mimicry (**antibodies to GM1 gangliosides**)

Question 36

C jejuni source, transmission, and epidemiology

Answer 36

Zoonosis from chickens and turkey **Fecal-oral** transmission (consumption of contaminated **poultry** or milk) Peaks in **summer**

Question 37

C. jejuni pathogenic factor? What does bacteremia indicate with this organism?

Answer 37

* Pathogenic factor = inflammatory enterotoxin * Bacteremia indicates an invasive potential

Question 38

C.jejuni treatment? When are antibiotics used, and which ones?

Answer 38

Oral rehydration Systemic infections: * Tetracycline * Quinolones * Clarithromycin

Question 39

C. fetus grows at...

Answer 39

25 degrees, but not at 42

Question 40

C. fetus usually causes ____ infections. It rarely causes \_\_\_\_\_\_\_

Answer 40

Systemic Diarrhea

Question 41

C. fetus source? Who does it infect?

Answer 41

Undercooked/contaminated beef Infects elderly & immunocompromised patients

Question 42

C. fetus major virulence factor?

Answer 42

S-layer protein \*\*inhibits complement fixation by C3b = less opsonization Lowered CMIR

Question 43

C. fetus antibiotics?

Answer 43

Tetracyclines, macrolides, quinolones

Question 44

H. Pylori appearance? Motile/nonmotile?

Answer 44

gram negative spirillum --- "Lazy S" motile at 37 degrees?

Question 45

H. Pylori growth characteristics (plates)

Answer 45

**Oxidase +** and **catalase +** Microaerophile _acid sensitive at pH 4.0_

Question 46

Major virulence factor of H. Pylori

Answer 46

Huge amounts of **_urease_** (Urease test positive in minutes to hours)

Question 47

H. pylori usually considered a ____ infection

Answer 47

**chronic,** **non-invasive**

Question 48

Colonization of H. Pylori is associated with

Answer 48

Lewis blood group adhesin --\> stimulation of GASTRIN production, which stimulates ACID production in fundus

Question 49

H. Pylori infection is associated with...

Answer 49

* gastric/duodenal ulcers * gastric adenocarcinoma

Question 50

Detection of H. Pylori (methods?)

Answer 50

Serology, Gram stain, culture **_Urea breath test_** = most effective * ¹⁴C urea is fed -\>\> detect ¹⁴CO2 in breath (can happen within minutes)

Question 51

H. Pylori carrier rate?

Answer 51

50% (80% in ulcer patients)

Question 52

H. Pylori has a strong corrleation with ___ allele

Answer 52

TLR1

Question 53

What doyou have to look out for regarding H. Pylori infections?

Answer 53

They may be masked by PPI's in patients undergoing long term GERD treatment

Question 54

H. Pylori Pathogenic steps

Answer 54

1. Binds to _base_ of mucosal cells (pH is 7.4 instead of 2) 2. Binds to _Lewis antigen_ (O) 3. Urease _buffers pH_ by forming NH3 from urea 4. Produce **_vacuolating toxin VacA_**

Question 55

What is the VacA toxin?

Answer 55

1. activated by stomach acid 2. binds to lipid rafts (sphingomyelin) in epithelial cells 3. inserts into cell as **_selective anion channel_** 4. causes vacuolation and urea release, and inhibits antigen presentation (and thus T cells activation)

Question 56

Ulcer strains of H. Pylori produce \_\_\_\_\_\_. What is it (three things)?

Answer 56

_CagA_ * secreted by T4SS * **induces apoptosis** * Potential _oncoprotein_

Question 57

Treatment of H. Pylori?

Answer 57

Three-pronged approach 1. Treat ULCER with **bismuth subsalicylate** 2. Treat INFECTION with **Tetracycline** or **Macrolide+Mzole** 3. Treat ACID with **PPI**

Question 58

H pylori ulcer only recovers if...

Answer 58

The infection is treated (bicarbonate only allows H. pylori to spread)