Helicobacter, Pseudomonas, Bordetella Corynebacterium - Exam III Flashcards
Describe the gram stain, and shape of helicopter pylori:
Gram negative, vibrio- curved-spiral rod
Curved spiral-rod shape that some bacteria take on:
vibrio
List the virulence factors of helicobacter pylori:
- Urease
- VacA
- CagA
- Mucinase
- Flagella
Describe the role of the virulence factor “urease” in helicobacter pylori infection:
Urease breaks down urea into ammonia which causes a pH increase leading to the neutralization of stomach acid
Describe the role of the virulence factor “VacA” in helicobacter pylori infection:
This is a protein that acts on gastric mucosal epithelia an promotes the flow of urea into the stomach
Describe the role of the virulence factor “CagA” in helicobacter pylori infection:
This is a protein that is injected into host epithelia that causes cell changes (prelude to cancer)
Describe the role of the virulence factor “mucinase” in helicobacter pylori infection:
This is an enzyme that degrades the mucus layer allowing for the bacteria to penetrate
Describe the role of the virulence function of “flagella” in helicobacter pylori infection:
very important for the colonization on the epithelial surface of the stomach
This is a protein that acts on gastric mucosal epithelia an promotes the flow of urea into the stomach in helicobacter pylori
VacA
breaks down urea into ammonia which causes a pH increase leading to the neutralization of stomach acid in helicobacter pylori
Urease
breaks down urea into ammonia which causes a pH increase leading to the neutralization of stomach acid in helicobacter pylori
Urease
This is a protein that is injected into host epithelia that causes cell changes (prelude to cancer) in helicobacter pylori
CagA
This is an enzyme that degrades the mucus layer allowing for the bacteria to penetrate in helicobacter pylori:
mucinase
VacA is also a ____ that induces damage to cells
cytotoxin
What allows helicobacter pylori organisms to survive the acidity of the stomach juices
urease
Once the helicobacter pylori reach the mucous layer, they penetrate the epithelial surface causing:
inflammatory response
Helicobacter Pylori’s ability to thin the mucus lining will cause:
ulcers in 10-20% of infected individuals
Only a small percentage of individuals infected with helicobacter pylori will develop cancer however:
more than 90% of individuals with stomach cancer are infected with H. Pylori
In most people with helicobacter pylori infections, they present:
symptom free
Describe the shape and gram stain of pseudomonas aeruginosa:
gram NEGATIVE; short rods
Describe the flagella on pseudomonas:
polar; one or more; high mobility
Describe the oxygen requirements for pseudomonas aeruginosa:
obligate aerobes
Describe the nutrient requirements of pseudomonas aeruginosa:
simple nutrient requirements and able to grow on hundreds of carbon sources (acetate for example)
What is the temperature range in which pseudomonas aeruginosa can grow and multiply:
broad temperature range 20-43 degrees celcius
List the virulence factors of pseudomonas aeruginosa:
- alginate
- LPS
What is the function of the virulence factor “alginate” in pseudomonas aeruginosa:
adherence; protection from dehydration; immune invasion, biofilm formation
What is the function of the virulence factor “LPS” in pseudomonas aeruginosa:
- Lipid A is endotoxic
- core interacts with cystic fibrosis transmembrane conductance regulator (CFTR)
- O-antigen protects from compliment/mediated killing
CFTR=
Cystic fibrosis transmembrane regulator
Pseudomonas Aeruginosa is considered a ____ pathogen
opportunistic
Give an example of when pseudomonas aerguinosa might cause opportunistic infection:
- cancer
- cystic fibrosis
- disease or weakened immunity
Pseudomonas aeruginosa is common in the:
environment (water + soil)
What is an example of a perfect culture condition for pseudomonas aeruginosa?
Hot tub
Why might a hot tub be a great environment to grow pseudomonas aeruginosa?
Pseudomonas are heat tolerant
Pseudomonas aeruginosa are resistant to:
- many chemical disinfectants (like iodine)
- many antibiotics
What allows for pseudomonas aeruginoas to be resistant to many antibiotics?
R-plasmid
What allows pseudomonas aeruginosa to be resistant to many chemical disinfectants?
capsule + alginate
Pseudomonas aeruginosa are a major problem in:
Hospitals (due to nosocomial infections)
Give examples of when pseudomonas aeruginosa may cause infections in a hospital setting:
- lungs - ventilators & CF patients
- skin- burn victims
- bladder infections
- ear infections
- eye infections - contact lenses
What strains of pseudomonas aeruginosa may affect the lungs in patients on a vent or with CF:
mucoid strains
Swimmers ear is also called ____ and may be caused by ___.
Otitis externa; pseudomonas aeruginosa
What bacteria has a characteristic green sheen?
pseudomonas aeruginosa
What are two characteristic factors of pseudomonas aeruginosa that are also virulence factors?
soluble blue green dyes pyocyanin and pyoverdin
one major clinical feature in which pseudomonas causes infection is in:
pulmonary tract (CF patients)
What is the major epidemiology of pseudomonas aeruginosa?
Nosocomial infection
Describe the gram stain and shape of bordetella pertussis:
Gram negative; coccobacilli
Describe “coccobacilli”
Not quite quite rods, not quite cocci
What are the oxygen requirements of bodetella pertussis?
strict aerobe
Because bordetella pertussis lack a flagella, they are:
non-motile
Bordetella pertussis contain a ____ that serves as a virulence factor:
capsule
Describe the growth and location of B. Pertussis:
They show dense growth in the lower respiratory tract (bronchi & bronchioli) but without cell invasion and induce strong mucus secretion
What is the only known reservoir of B. Pertussis and why is this significant?
Humans- adult humans are the reservoir and pass it on to children who show disease symptoms
Whooping cough is a childhood illness caused by:
Bordetella pertussis
Bordetella pertussis is able to adhere to ___ but does NOT ____.
Ciliary respiratory tract cells; invade
What is the main cause of illness with B. Pertussis?
The toxins associated
What are the toxins of B. Pertussis?
- pertussis toxin (ptx)
- Secreted invasive adenylate cyclase/ hemolysin
- tracheal cytotoxin
Describe the mechanism of pertussis toxin (ptx):
ADP-ribosylation of G-protein leading to increased cAMP which results in increased mucus and other secretions
Describe the mechanism of the secreted invasive adenylate cyclase/ hemolysin toxin of B. Pertussis:
invades epithelial cells and further increases cAMP production = even more mucus
Describe the mechanism of the tracheal cytotoxin produced by B. Pertussis:
induces nitric oxide release that ends up killing ciliated cells
_____ is a toxin of B. pertussis that is actually not a protein, rather just a component of the peptidoglycan layer:
tracheal cytotoxin
Describe the structure of tracheal cytotoxin (in B. Pertussis)
disaccharide-tetrapeptide
The the tracheal cytotoxin in B. Pertussis causes:
nitric oxide release (NO)
Most gram negative bacteria keep tracheal cytotoxin (TCT) within the cell wall by using a transporter preotin to recycle it, however, B. Pertussis:
is not capable of recycling TCT and is escapes to the surrounding environment where it has devastating effects on ciliated cells
What is the treatment of B. Pertussis?
DTaP vaccine (Diphtheria Tetanus acellular Pertussis)
What is important about the Pertussis component of the DTaP vaccine?
Important that the pertussis is ACELLULAR
Describe the epidemiology of B. pertussis:
aerosol transmission- children’s disease (but mild symptoms in adults who are the reservoir)
Describe the gram stain and shape of corynebacterium diphtheriae:
gram positive; pleomorphic (often club-shaped rods)
What does pleiomorphic mean?
doesn’t have a particular set shape
Corynebacterium diphtheriae can be part of our normal oral flora but can cause infection, it is considered:
an opportunistic pathogen
Describe the location of effects caused by infection of corynebacterium diphtheriae:
oral pathogen with systemic effects
Describe the cytotoxin of corynebacterium diphtheriae:
Diphtheria toxin; phage-beta encoded; AB toxin
What is the diphtheria toxin responsible for?
Pseudomembrane in throat; and heart & kidney damage
How does the diphtheria toxin produced by corynebacterium diphtheriae function:
Inhibits protein synthesis by inactivating an elongation factor of eukaryotic cells. This results in the killing of local cells (in the throat) but can also be carried in the blood stream to various organs
Describe the mechanism of the diphtheria toxin:
NAD + EF-2 —-> ADP ribose-EF2 (inactivated) + nicotinamide
The diphtheria toxin is a ___ toxin
AB
The diphtheria toxin binds to a receptor via the ___ component
B component
How does the diphtheria toxin get into the cell?
endocytosis (endosomes)
What happens when the endosome containing the diphtheria toxin matures?
Results in cleavage of the A component from the B component
Describe the A component of the diphtheria toxin and its function:
The A component is an ADP ribosylase; It will add an ADP ribose group to the translation factor EF2
What happens when the A component of the diphtheria toxin adds and ADP ribose group to the translation factor EF2?
This stops translation causing local cell death (throat)
What virulence factor does corynebacterium diphtheriae contain?
- throat adhesion
- diptheriae toxin
Ultimately the diptheria toxin causes:
ADP-ribosylation of EF2 causing translation to stop (cell death & pseudomembrane)
What toxin is responsible for ADP-ribosylation of EF2 causing termination of translation?
Diphtheria toxin
What is the significance of the pseudomembrane caused by the diphtheria toxin?
can cause blockage of airway
What is the pseudomembrane caused by diphtheria toxin comprised of?
- C. diphtheriae cells
- damaged host cells
- blood
List the LOCAL disease risks from the diphtheria toxin:
- paralysis (impaired swallowing & peripheral neuritis)
- suffocation (due to blockage)
List the SYSTEMIC disease risks from the diphtheria toxin:
- cardiac arrythmia
- kidney failure
Discuss the treatment to infection with corynebacterium diphtheriae:
prevent toxoid by vaccination
Describe the epidemiology of the corynebacterium diphtheriae:
Spread by saliva droplets
What vaccination is diphtheria a part of?
DTaP
Being vaccinated against diphtheria is part of:
childhood vaccine protocol
What does DPT stand for?
Diphtheria, pertussis, and tetanus