00:01
Bordetella Pertussis, a bacteria. Bordetella Pertussis is a
gram-negative, encapsulated coccobacillus,
meaning that it is part rod-shaped and part coccus-shaped
and you can see a picture of that on the right side of the
screen.
00:16
Perhaps the best way to describe the shape itself is as an
oval-shaped.
00:20
When growing, it is a facultative aerobe and it does require
growth within cells.
00:27
It also is oxidase-positive and it grows best if it grows at
all on specialized agar as you see listed there.
00:35
How does the disease occur in terms of pathogenesis?
And this is interesting because Bordetella Pertussis has
several different toxins,
all which have the ultimate function of poisoning the
ciliated epithelial cells
and causing the body to hypersecrete both mucus and
inflammation
so that it creates excessive respiratory secretions and
poisons the ability to clear them.
01:04
So, as you can see here, the first step is for Bordetella
Pertussis to bind to ciliated epithelial cells.
01:12
On the bottom part of the slide, you see fully functional
respiratory epithelium standing in the line
On the bottom part of the slide, you see fully functional
respiratory epithelium standing in the line
On the bottom part of the slide, you see fully functional
ciliated epithelium standing in line
and the cilia normally would be waving under ATP generation
creating
what’s called the mucociliary elevator to elevate mucus from
the lower respiratory portions
up to the higher part of the trachea where it can be cleared
by a normal expressive cough or swallowed normally.
01:37
However, if Bordetella Pertussis binds to the ciliated
cells,
then, ultimately, it poisons those ciliary functions,
hypersecretes inflammatory secretions
and then, causes downstream effects which we’ll talk about
very shortly.
01:54
In addition to being effective at creating this
pathogenesis,
it also is very effective at surviving and because
Bordetella Pertussis is an intracellular organism,
it can evade many parts of the immune system quite
successfully.
02:10
Now, let’s look at those pathogenic factors.
02:14
The first is the pertussis exotoxin which acts by inhibiting
the G protein.
02:20
G protein’s major responsibility is to suppress or control
production of cyclic AMP.
02:27
So, if one inhibits the off switch or inhibits the
inhibitor,
then, cyclic AMP can be expressed without much suppression
within the respiratory cells.
02:40
This causes extreme overchange of fluids followed by mucous
secretions
and that buildup of inflammatory mass within the respiratory
tree.
02:49
Bordetella Pertussis also has hemagglutinin which has
effects on coagulation and also on vascular permeability
and it creates an adenylate cyclase toxin which also impacts
the function of cyclic AMP
and in this case, has downstream effects on blocking
effector function within the immune system.
03:11
However, the key part of Bordetella Pertussis’ function is
the tracheal cytotoxin
which is managed and mentioned before,
which was mentioned before,
damages the ciliated tracheal cells. Research has
demonstrated that organisms,
Bordetella organisms in which the specific function of
tracheal cytotoxin is removed or blocked
are unable to cause the disease we know of as Pertussis, as
whooping cough.
03:39
But if one restores function to the tracheal cytotoxin,
then, the entire pathogenicity is restored.
03:46
So, critical, necessarily, and sufficient is the tracheal
cytotoxin to the disease expressed by Bordetella Pertussis.
03:54
And in addition, it has an endotoxin which is part of what
induces the pyrogenic or the fever responses.
04:02
So, what does Pertussis look like?
First of all, the organism itself is transmitted through
aspiration and inhalation of respiratory droplets
and these are the fine respiratory droplets such as can
persist in midair for quite long distances and for quite
long times.
04:20
Patients at risk for developing Pertussis actually can be
anybody.
04:25
However, if one has some amount of seroprotection from
vaccination
or immunomodulatory effects, then, one can avoid disease.
04:35
Therefore, those at risk for getting Pertussis are those who
are unvaccinated, under-vaccinated,
meaning immunity has waned, and those who are
immunosuppressed
which may be children and adults, or even newborn babies.
04:49
In fact, the highest risk of Pertussis is in babies up to
age two months
prior to their very first Pertussis vaccine if they are
exposed to other family members who themselves have
Pertussis.
05:02
The incubation period, seven to 10 days, typically, about a
week.
05:06
And then, when infection develops, it is associated with
very prominent lymphocytosis.
05:12
This by itself although not unique, is certainly part of the
reason that Pertussis can be mistaken for a viral
infection,
therefore, limiting its evaluation, its diagnosis, and its
potential treatment and support.
05:27
Disease progression for Pertussis is quite unique as it
occurs in three stages,
each of which has a different phenotype, a different
appearance.
05:37
Stage one is so called the catarrhal stage and this may last
one to two weeks.
05:42
When you think catarrhal stage, think really bad cold.
05:47
So, runny nose, low grade fevers, maybe a bit of the cough
but not the classic cough and it is at this time this
non-specific I might just have a virus stage,
the patients are the most contagious and they are truly
really contagious.
06:02
Attack rate for a family exposed to one family member with
Pertussis is well over 50, 5-0 percent.
06:11
The next stage, stage two is the paroxysmal stage.
06:15
This may be anywhere from just one week if one is lucky or
up to six weeks,
it could even go up to 10 weeks or so. This is the stage in
which the classic cough,
the Pertussis paroxysmal or whooping cough may occur
and although I won’t demonstrate here to preserve your ears,
the whoop is really quite unique.
06:35
Paroxysmal coughing meaning cough, cough, cough, cough,
cough, cough, cough, running out of breath,
and then, a whoop of inspired air trying to catch the breath
back.
06:44
As you can imagine, an incredibly unpleasant experience to
go through
because one feels as if one is about to drown and the
coughing sometimes is so severe that people break ribs
and they certainly may vomit during the cough and after the
cough.
07:00
So, what’s called a post-pertussive or a post-paroxysmal
cough, cough, cough, cough, throw up,
then, whoop also increases extreme discomfort and also
allows the patient to feel just miserable.
07:15
So, this is a really nasty part of Pertussis and
unfortunately as I mentioned, it can go up to 10 weeks.
07:21
The third stage, this is the convalescent stage, so called
when recovery occurs.
07:27
However, that may be a bit of a misnomer because that
horrible cough
I mentioned may still be persistent for many of these weeks.
07:35
In fact, Pertussis or whooping cough has been called the 100
days cough
because the cough may last exactly that.
07:45
I’m not even including the catarrhal stage.
07:47
I’m talking 100 days of that horrible breaking ribs
post-coughing emesis cough, 100 days.
07:56
So, eventually after this, the recovery occurs and the
patient,
if they have survived and done quite well can go on about
their business.
08:04
Treatment, of course, treatment of Pertussis as with all
other things is best accomplished by prevention
and prevention does exist in the form of vaccines,
several different type products, either acellular or an
inactivated whole cell vaccines exist.
08:21
This is one of the primary series of vaccines for children
beginning at age two months,
again, at four, six, and 12 to 15 months with a booster but
adults, young adults,
and middle-aged children also require boosters as well
because as we’re discovering, immunity may wane.
08:37
For those patients whose immunity is unknown or not
established
and who have close contact with a patient with active
Pertussis, prophylactic antibiotics are indicated
and those antibiotics are most typically the macrolides such
as erythromycin or azithromycin.
08:58
For patients who cannot tolerate those antibiotics and GI or
gastrointestinal effects are quite prominent,
then, the sulphonamides may be appropriate.
09:07
Importantly, it is not possible to treat Pertussis with an
antibiotic.
09:12
One is simply treating to minimize the contagious period.
09:16
There will be no impact on length of symptoms or that 100
days cough that we just talked about.
09:23
So, antibiotics while we do administer them, are only to
help with the contagiousness period
and to be used for prophylaxis for those at risk.
09:32
So, Bordetella Pertussis is quite a nasty. It is a long
disease associated with that and the morbidity,
the extreme effect associated with that are quite
significant.
09:45
Keep in mind and most importantly, vaccines and prevention
is the most appropriate way to intervene
and prophylactic antibiotics while effective for those
exposed do not affect the treatment
or the cure rate of the Pertussis itself.