Bordetella Pertussis Flashcards
How Bordetella is transmitted?
usually by aerosoles, directly from infected to susceptible individual through the respiratory tract.
At which stage the person is the most infectious?
At the catarrhal stage
Who are the only reservoir?
Humans are the only natural hosts
On which locus are present all the genes related to virulence?
On locus called BVG, Bordetella virulence gene
What it’s called the antigenic variation?
Since there is always upstream and downstream expression of some genes in an orchestrated manner
What is the phase variation?
It happens after a mutation in BVG such that none of the virulence genes are expressed
What are the virulence factors?
The capsule Pili Pertussis toxin Adenylate cyclase toxin Tracheal cytotoxin Dermonecrotic toxin Filamentous hemagglutinin LPS
To which cells pili will adhere?
Ciliated cells
Which toxin is the first to be activated?
Adenylate cyclase toxin
It works at the beginning of the infection, initiating it
What is the major virulence factor?
Pertussis toxin
What induces the tracheal cytotoxin at the beginning of the infection? At the end of the infection?
at the beginning of the infection, it induces ciliastasis (it stops the movement of cilia)
At the end of the infection, it causes extrusion of ciliated epithelial cells.
At which stage the person is infectious?
At the end of the infection when there is extrusion of ciliated epithelial cells
Which toxin is related to necrosis?
The dermonecrotic toxin
What is the importance of the filamentous hemagglutinin?
Ab directed against it inhibit attachment to susceptible cells so those proteins give protection during vaccine
What is the clinical presentation?
Whooping cough or pertussis
What is the typical manifestation for an infection with Bordetella?
Paroxysmal cough which ends up by vomiting, along with an absolute lymphocytosis in a blood test
What is the susceptible age group?
children less than 5 years old
What is the incubation period?
7 to 10 days
Can we have a bacteremia?
That is very rarely a bacteremia
What are the 3 stages of the disease?
Catarrhal stage
Paroxysmal stage
Convalescent phase
During which stage we find the highest amount of bacteria?
What happens during this stage?
During the catarrhal stage
During this stage there is only extrusion of bacteria
Why proper diagnosis and treatment should be done during this stage?
Because the person is highly infectious and later the number of bacteria will decrease rendering antibiotics less effective
What happens during the paroxysmal stage?
There is extrusion of bacteria with ciliated cells
What is the paroxysmal cough?
During a single exhalation, there is 10 to 30 repetitive, forceful and sudden coughs which are followed by a single inhalation with spasm of the larynx and glottis which is the whoop
What are the manifestations during paroxysmal stage?
The person cannot breathe properly, so there has to be vomiting after each spasm, in order to get rid of excess mucus plugs that weren’t cleared by coughing
What do we see in the blood test?
Leukocytosis
Which Ab are detected at the end of the paroxysmal stage?
Why did you not have a diagnostic value?
At the end of the stage, Ab test can detect Ab to the filamentous hemagglutinin but it is of no diagnostic value because we passed infectious phase
What do we have during the convalescent phase?
There can be a secondary complication by Strep, Staph, Hemophilus
Do patients develop permanent immunity?
Yes they do
From where the specimen should be taken?
How do we take it?
From the throat
Rather than taking it by cotton swab, we use a nasal saline wash. The saline solution is introduced inside the nose, then washing, then aspiration
Are they gram-negative or gram-positive?
Gram negative
Are they aerobic, anaerobic or facultative anaerobes?
They are strictly aerobic
Are they motile? Spore forming?
They are nonmotile, non-spore forming
What is their selective medium? What does it contain?
It is the Bordet-Gengou medium
It contains potato, glycerol, blood, antibiotics that inhibit the growth of other bacteria
At which temperature do they grow? What becomes the color of the medium?
They grow at 36°C and the medium will become black
Which test is done after the culture?
Fluorescent Ab test
Which antibiotics are used?
Erythromycin or tetracycline for at least two weeks
Which vaccine is given? From what it is made?
He triple vaccine
It contains the pertussis toxoid and the filamentous hemagglutinin
What’s the type of this toxin? What does it cause?
It is an AB toxin
It’s induces lymphocytosis, hypoglycemia since it activates islet cells and increases production of insulin
