Exam 3 Lecture 22 Flashcards by Aditi Iyer

Describe the gram stain of Campylobacter and Helicobacter

gram-negative helical rods

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Campylobacter and Helicobacter are part of which broad group?

Epsilonproteobacteria

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True or false: though they were discovered in the last 50 years, Campylobacter and Helicobacter are common bacterial pathogens

True

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Campylobacter and Helicobacter are _____ and ____

microaerophilic; fastidious

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Campylobacter and Helicobacter infect the __ ___ of humans and other animals

GI tract

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True or false: Campylobacter and Helicobacter do not have flagellar motility

False

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C. jejuni has ____ flagella, which contributes to what kind of motility?

bipolar; darting motility

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Lophotrichous flagella

Multiple flagella found at one end of the bacterium

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H. pylori has ____ flagella, which allows for:

lophotrichous; penetration of mucus (which likely attributes to its ability to get into the tissue and cause infection)

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How do Campylobacter and Helicobacter have molecular mimicry?

Their LPS/LOS structures mimic host glycosylation, which can induce autoantibodies (those that mistakenly target the host)

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How many species of Campylobacter do we know of? How many subspecies?

32 species; 9 subspecies

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True or false: Campylobacter is the major cause of foodborne bacterial infections in developed nations

True (more than Salmonella, E. coli, Shigella combined)

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Does Campylobacter cause disease via low or high inoculum?

Low (400-500 sufficient to cause infection)

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Most Campylobacter infections are caused by:

C. jejuni

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C. coli attributes to -% of Campylobacter infections

1-25%

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True or false: Campylobacter can commonly colonize domestic animals where it doesn’t cause much disease.

True

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C. jejuni causes ____, which consists of what symptoms?

Enteritis; symptoms = diarrhea; sometimes bloody, fever, abdominal pain, inflammation

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C. jejuni symptoms usually appear in __-__ hours. The range is - days.

24-48 hours; 1-7 days

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True or false: C. jejuni enteritis usually is self-limiting and resolves within a week

True

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Sometimes, C. jejuni infection can become _____, which can lead to other diseases, such as:

extraintestinal; biliary tract, bacteremia, meningitis, others

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How is C. jejuni infection treated?

fluids and electrolytes, antibiotics for severe infections

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True or false: antibiotic resistance is a problem when treating C. jejuni

True - presumably due to resistance having developed in livestock

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Which antibiotics are used for treating C. jejuni?

Azithromycin, Ciprofloxacin

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True or false: For diagnosing C. jejuni, culture via selective media is the gold standard

True

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Besides culture, what are some other ways to diagnose C. jejuni?

1. looking for darting motility in fresh stool samples | 2. serum serology and PCR

Most cases of C. jejuni are due to ____ ____

sporadic zoonosis

You can contract C. jejuni infection through: (2; hint - one is rare)

1. contaminated/undercooked poultry | 2. (rare) pets, contact with farm animals, person to person

True or false: raw milk or untreated water can cause outbreaks in C. jejuni

True

C. jejuni cases peak during ___ ___

warmer months

What are the four steps of C. jejuni pathogenesis?

1. adheres to intestinal epithelial cells 2. induced toxin-mediated cell damage 3. uses cytolethal distending toxin to induce cell cycle arrest 4. performs endocytosis and transcytosis (which is thought to be important for immune evasion)

True or false: C. jejuni flagella are required for infection

True (darting motility)

Regarding C. jejuni flagella, FlaA and FlaB expression can be turned on or off due to ___ ____, which is controlled by ___-___ ____

phase variation; slip-strand mispairing

Which flagellin monomers make up the C. jejuni flagella?

FlaA and FlaB

True or false: generally, bacterial flagella are normally glycosylated

False

C. jejuni flagellin glycosylation is important for _______ and _____ _____

autoagglutination; microcolony formation

Besides making up the flagellar structure, what else is the basal body in C. jejuni responsible for?

Exporting other proteins, such as FlaC, Cia proteins, and FspA

Generally, flagella are made via what type of secretion system?

(Modified) T3SS

Name the C. jejuni virulence factors (7)

1. motility 2. chemotaxis 3. adhesion and invasion 4. capsule 5. iron uptake 6. biofilm formation and antibiotic resistance 7. LPS/LOS

Describe the chemotaxis of C. jejuni

attracted to mucus, glycoproteins of mucus, nutrients | repelled by bile

C. jejuni adheres to host ____ via what proteins?

CadF and FlpA

Which protein of C. jejuni binds to host heat shock protein?

JlpA

True or false: C. jejuni flagella are thought to be important for adhesion to host cells.

True

True or false: in addition to FlaA/FlaB expression, C. jejuni turns capsule biosynthesis on/off via slip-strand mispairing

True

C. jejuni capsule is important for:

survival, adherence, immune evasion

How many serotypes exist in C. jejuni?

over 100

What serotypes are associated with GBS?

Serotypes O19 and O41

What type of toxin is CDT?

AB2

CdtB gene codes for? And what functions does this protein product have?

A subunit of the CDT toxin; has DNase and phospholipase activity

What do CdtA and CdtC genes code for?

binding subunits of the AB2 CDT toxin

CdtA and CdtC bind to ____-rich regions on the host cell membrane and drives internalization of the toxin via _____-____ __

cholesterol; clathrin-coated pits

True or false: the CDT toxin is unique solely in C. jejuni

False - found in many Gram negative organisms, such as E. coli, H. ducreyi, Helicobacter spp, S. Typhi, Shigella

How does C. jejuni CDT cause cell cycle arrest/apoptosis?

B subunit migrates into the nucleus, induces double strand breaks; also activates ATM, p53

What does GBS syndrome cause?

ascending paralysis

Approximately _/___ patients develop GBS after C. jejuni infection

1/1000

True or false: GBS correlates with presence of anti-GM1, anti-GD1a, IgG (antibodies against host proteins)

True - this attributes to paralysis

In GBS, antibodies that are produced attack the ___ and assemble complement, essentially destroying the ___

nerves

In addition to causing GBS, C. jejuni can also cause ____ ____

reactive arthritis

C. fetus major reservoir

animals such as cattle, sheep, reptiles

C. fetus grows optimally at __ºC

37ºC

C. fetus can cause ____ and ___ ___

diarrhea; fetus loss

True or false: C. fetus was the first Campylobacter characterized

True

____ grows more slowly than Campylobacter

Helicobacter

True or false: there is a correlation between H. pylori and peptic cancer

True

H. pylori infection occurs ___ in life and can ____ for life

early; persist

What is the H. pylori reservoir?

stomach

H. pylori is ____ transmitted within families. As such, there is a strong ____ ____ to the genetic variation of Helicobacter spp.

vertically; ethnogeographic signature

Most cases of H. pylori are ____ ____

asymptomatic gastritis

H. pylori can cause what type of ulcers?

gastric and duodenal ulcers

H. pylori can also cause ___ ___ ___ ___, which resolves upon eradication of infection.

Mucosa Associated Lymphoid Tissue

Asymptomatic gastritis is characterized by? (3)

1. neutrophil infiltration 2. proinflammatory cytokines (increases acid) 3. can progress to atrophic gastritis (loss of parietal cells, less acid)

Parietal cells

epithelial cells that line the stomach and secrete HCl

What does H. pylori gastritis look like?

bumpy lining, hyperplasia, loss of parietal cells, immune cells infiltrate, inflammation

How does H. pylori survive the acidic environment of the stomach?

secretes urease

True or false: patients with gastric cancer know early on that they have it

False - often is silent until tumor grows so large that it becomes hard to eat

True or false: MALT lymphoma is rare

True

H. pylori gastric cancer ___ doesn't match ___. Ex: China

incidence; prevalence

H. pylori diagnosis (4)

1. urea breath test (carbon isotope) 2. stool antigen test 3. serological test (anti-H. pylori IgG) 4. endoscopy and biopsy (for culture and histology purposes)

Do we treat H. pylori if there are no symptoms?

If there are symptoms or cancer risk, treat H. pylori with:

Combination therapy - 2 antibiotics - drug to reduce acid - bismuth to promote mucosal healing

True or false: H. pylori treatments rarely fail

False- it can happen so we are wary of it due to resistance, pH effect on drugs, non-compliance due to long course of treatment

Majority of H. pylori live in:

mucus layer overlying the gastric epithelium

Urease has two main functions, which are:

1. buffers stomach acid via cleaving urease to make NH3 | 2. changes rheological properties of mucin to make it easier to swim through

H. pylori uses ___ ___ and ____ __ __ to get to epithelium

flagellar motility; helical cell shape

H. pylori toxins (3)

VacA, Nap, CagA

VacA

vacuolating cytotoxin

Nap

recruit immune cells

CagA

subvert host cell signaling

H. pylori uses adhesins __ and __ to bind to? (respectively)

BabA and SabA; lewis antigens; sialyl-lewis antigens

True or false: there is molecular mimicry with H. pylori due to Lewis antigens on LPS

true

VacA has different ___ ___ ___ which can lead to higher/lower levels of its expression and binding ability

signal sequence polymorphisms

VacA induces cells to fill up with big ____, which is ____. It also increases the ____ of the epithelium

vacuoles; cytostatic; permeability

VacA can induce apoptosis via interaction with?

mitochondria

VacA can inhibit _-___

T- cells

Cag is coded within _____ ___

pathogenicity island

Cag is associated with ___ and ___

ulcer and cancer

Cag is displaced into a host cell via what secretion system?

T4SS

Cag induces _____ ___

proinflammatory cytokines

translocation of CagA into host does what two things?

1. activate growth receptor signaling pathways | 2. induce cell shape changes and motility

True or false: Cag pathogenicity island is found in all strains of H. pylori

False - only in some strains, but found in those associated with causing ulcers/cancer

CagA has ___ motifs. East Asians in particular have the _ motif which binds ___ much more tightly.

EPIYA; D; SHP-2

SHP-2 binds to what specifically?

Phosphorylated Y within EPIYA

True or false: Kids who have H. pylori are much more likely to have asthma and other allergic conditions

False: less likely

Regarding H. pylori, protection against allergies/chronic inflammatory disorders is mediated through ____ _ ___

regulatory T cells