Helicobacter, Pseudomonas, Bordetella, Cornyebacterium (EXAM III) Flashcards
Describe the gram stain & shape of helicobacter pylori:
Gram negative; virbrio (curved-spiral rod)
Curved spiral rod shape 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 causing 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 to promote 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 mucous layer allowing for the bacteria to penetrate
Describe the role of the virulence function of flagella in helicobacter pylori:
Very important for the colonization on the epithelial surface of the stomach
In helicobacter pylori, this breaks down urea into ammonia causing a pH increase leading to the neutralization of stomach acid
Urease
In helicobacter pylori, this is a protein that acts on gastric mucosal epithelia to promote flow of urea into the stomach
VacA
In helicobacter pylori, this is a protein that is injected into host epithelia that causes cell changes (prelude to cancer)
CagA
In helicobacter pylori, this is an enzyme that degrades the mucous layer allowing for the bacteria to penetrate
Mucinase
VacA is also a _____ that induces damage to cells
Cytotoxin
What allows helicobacter pylori organisms to survive the acidity of stomach juices?
Urease
Once the helicobacter pylori reach the mucous layer they penetrate the epithelial surface causing:
An inflammatory response
Helicobacter pylori’s ability to thin the mucous 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 90% of individuals with stomach cancer are infected with H. Pylori
In most people with H. Pylori infections, they present
Symptom-free
Describe the gram stain & shape of pseudomas aeruginosa:
Gram negative; short rods
Describe the flagella on psuedomonas:
They are polar; one or more; allow high mobility
Describe the oxygen requirements for pseudomonas aeruginosa:
Obligate aerobe
Describe the nutrient requirements of pseudomonas aeruginosa:
Simple nutrient requirements- able to grow on hundreds of carbon sources for example
What is the temperature range in which pseudomonas aeruginosa can grow & multiply:
Broad temperature range; 20-43 degrees celcius
List the virulence factors of pseudomonas aeruginosa:
- Aliginate
- Lipopolysaccharide
What is the function of the virulence factor “alginate” in pseudomonas aeruginosa?
Adherence, protection from dehydration & immune invasion, a source of biofilm formation
What is the function of the virulence factor lipopolysaccharide in pseudomonas aeruginosa?
- Lipid A portion is endotoxic
- core interacts with cystic fibrosis transmembrane conductance regulator (CFTR)
- O antigen protects from complement-mediated killing
CFTR=
Cystic fibrosis transmembrane conductance regulator
Pseudomonas aeruginosa is considered a _____ pathogen
Opportunistic
Give examples of when pseudomonas aeruginosa may 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 an ideal environment to grow pseudomonas aeruginosa?
Pseudomonas are heat tolerant
Pseudomonas aeruginosa are resistant to:
- Many chemical disinfections (like iodine)
- Many antibiotics
What allows for pseudomonas aeruginosa to be resistant to many antibiotics?
R-plasmid
What allows pseudomonas aeruginosa to be resistant to many chemical disinfectants?
Capsule & alignate
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 psuedomonas aeruginosa may infect the lungs in patients with CF or on a ventilator?
Mucoid strains
Swimmer’s 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 & pyoverdin
One major clinical feature in which pseudomonas causes infection is in:
Pulmonary tract- CF patients
What is the epidemiology of pseudomonas aeruginosa?
Nosocomial infections
Describe the gram stain & shape of bordetella pertussis:
Gram negative; coccobacilli
Describe what coccobacilli means:
Not quite rods, not quite bacilli
What are the oxygen requirements of bordetella 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 & location of B. Pertussis:
Show dense growth in the lower respiratory tract (bronchi & bronchioli) without cell invasion & induce strong mucus secretion
What is the only known reservoir of B. Pertussis & why is this significant?
Humans- adult humans are the reservoir and pass it on to children who show the disease symptoms
Whooping cough is a childhood illness caused by:
Bordetella pertussis
Bordetella is able to adhere to _____ to cause infection but it does not ____
Ciliated respiratory tract cells; invade
What is the main cause of illness with bordetella pertussis?
The toxins associated with B. pertussis
What are the toxins of Bordetella 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 mucous & other secretions
Describe the mechanism of the secreted invasive adenylate cyclase/hemolysin toxin of Bordetella Pertussis:
Invades epithelial cells further increases cAMP production = even more mucus
Describe the mechanism of the tracheal cytotoxin produced Bordetella 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 peptidoglycan layer
Tracheal cytotoxin
Describe the structure of the tracheal cytotoxin (in B. Pertussis):
Disaccharide-tetrapeptide
The tracheal cytotoxin of B. Pertussis causes:
Nitric oxide release (NO)
Most gram negative bacteria keep tracheal cytotoxin (TCT) within the cell wall by using transporter protein to recycle it, however B. Pertussis:
Is not capable of recycling TCT and it escapes to the surrounding environment where it has devastating effects on ciliated cells
What is the treatment of B. Pertussis?
DTaP vaccine (Diptheria, 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- mild symptoms in adults who are the reservoirs but ultimately a children’s disease
Describe the gram stain & shape of Corynebacterium Diphtheriae:
Gram +, pleiomorphic (often club-shaped) rods
What does pleiomorphic mean?
Doesn’t have a particular set shape
Because Corrynebacterium diptheriae 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 by corynebacterium diptheriae:
Oral pathogen with systemic effects
Describe the cytotoxin of Corynebacterium Diptheriae:
Diptheriae toxin; phage-beta encoded; A-B toxin
What is the diphtheria toxin responsible for?
Psuedomembrane in throat; heart & kidney damage
How the diphtheria toxin produced by Corynebacterium Diptheriae function?
Inhibits protein synthesis by inactivating an elongation factor or 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
A-B
The diphtheria toxin binds to a receptor via the ____ component
B
How does the diphtheria toxin get into the cell?
Internalized via endocytosis pathway into endosome
What the 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 a 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 an asp-ribose group to the translation factor EF2?
This stops translation causing local cell death (throat)
What virulence factors does Corynebacterium diptheriae contain?
- Throat adhesion
- Diphtheria toxin
Ultimately the diphtheria 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 throat and inhibit airway
What is the pseudomembrane caused by diphtheria toxin comprised of?
- C. Diptheriae cells
- Damaged host cells
- Blood
List the LOCAL disease risks from the diphtheria toxins:
- 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 Diptheriae:
Prevent toxoid by vaccination
Describe the epidemiology of Corynebacterium Diptheriae:
Spread by saliva droplets
What vaccination is diphtheria a part of?
DTaP
Because vaccinated against diphtheria is part of:
Childhood vaccine protocol
What does DPT stand for?
Diptheria, Pertussis, Tetanus