Exam 3 Lecture 22 Flashcards
Describe the gram stain of Campylobacter and Helicobacter
gram-negative helical rods
Campylobacter and Helicobacter are part of which broad group?
Epsilonproteobacteria
True or false: though they were discovered in the last 50 years, Campylobacter and Helicobacter are common bacterial pathogens
True
Campylobacter and Helicobacter are _____ and ____
microaerophilic; fastidious
Campylobacter and Helicobacter infect the __ ___ of humans and other animals
GI tract
True or false: Campylobacter and Helicobacter do not have flagellar motility
False
C. jejuni has ____ flagella, which contributes to what kind of motility?
bipolar; darting motility
Lophotrichous flagella
Multiple flagella found at one end of the bacterium
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)
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)
How many species of Campylobacter do we know of? How many subspecies?
32 species; 9 subspecies
True or false: Campylobacter is the major cause of foodborne bacterial infections in developed nations
True (more than Salmonella, E. coli, Shigella combined)
Does Campylobacter cause disease via low or high inoculum?
Low (400-500 sufficient to cause infection)
Most Campylobacter infections are caused by:
C. jejuni
C. coli attributes to -% of Campylobacter infections
1-25%
True or false: Campylobacter can commonly colonize domestic animals where it doesn’t cause much disease.
True
C. jejuni causes ____, which consists of what symptoms?
Enteritis; symptoms = diarrhea; sometimes bloody, fever, abdominal pain, inflammation
C. jejuni symptoms usually appear in __-__ hours. The range is - days.
24-48 hours; 1-7 days
True or false: C. jejuni enteritis usually is self-limiting and resolves within a week
True
Sometimes, C. jejuni infection can become _____, which can lead to other diseases, such as:
extraintestinal; biliary tract, bacteremia, meningitis, others
How is C. jejuni infection treated?
fluids and electrolytes, antibiotics for severe infections
True or false: antibiotic resistance is a problem when treating C. jejuni
True - presumably due to resistance having developed in livestock
Which antibiotics are used for treating C. jejuni?
Azithromycin, Ciprofloxacin
True or false: For diagnosing C. jejuni, culture via selective media is the gold standard
True
Besides culture, what are some other ways to diagnose C. jejuni?
- 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)
- 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?
- adheres to intestinal epithelial cells
- induced toxin-mediated cell damage
- uses cytolethal distending toxin to induce cell cycle arrest
- 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)
- motility
- chemotaxis
- adhesion and invasion
- capsule
- iron uptake
- biofilm formation and antibiotic resistance
- 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)
- neutrophil infiltration
- proinflammatory cytokines (increases acid)
- 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)
- urea breath test (carbon isotope)
- stool antigen test
- serological test (anti-H. pylori IgG)
- endoscopy and biopsy (for culture and histology purposes)
Do we treat H. pylori if there are no symptoms?
No
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:
- 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?
- 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
