00:01
In our discussion of
gastrointestinal tract infections,
we come to the
very large topic of
infectious diarrhea
and food poisoning.
00:13
We would certainly
define it as the acute onset
of excessive bowel
movements caused either directly
or indirectly by
microbial pathogens.
00:25
It's got a tremendous
impact on the world.
00:29
It's the second leading
cause of morbidity
and mortality with 3
million deaths a year.
00:37
And that's more
than 8,400 a day.
00:42
And unfortunately,
it affects our
young children in
developing countries.
00:47
And the main reason
for that is that they
don't have a lot
of fluid to start with.
00:52
And so if they start
losing a lot of fluid,
they lose a lot of blood volume
and they can get sick in a hurry.
01:01
Diarrhea is 1000 fold
higher in developing
countries than in
the United States.
01:08
But it still is a problem
in the United States
with 179 million cases a year,
17 million of which
are food-borne.
01:18
About 2 million of those
instances require hospitalization.
01:25
3000 deaths is a sizable amount,
and most of the deaths
occur among elderly persons.
01:33
In the United States,
the cost of food-borne illnesses
is estimated to be
as high as $90 billion
in medical care and lost
productivity every year.
01:41
The annual incidents
per 100,000 people
of domestically acquired
bacterial and parasitic infections
in 2019 in 10 US sights
is shown in this histogram.
01:52
Campylobacter leads the list
followed closely by salmonella,
then Shiga-toxin
producing E. coli or STEC,
Shigella, Cyclospora, a parasite,
Yersinia, Vibrio and Listeria.
02:05
Then, as far as the causes
of acute bacterial diarrhea,
if you're talking about
international travel,
we're talking about
these organisms.
02:16
E. coli, the cause of turista.
02:19
Some people call it
Montezuma's revenge.
02:23
Some people call it the
Green Apple Quickstep.
02:26
There are many names for it.
02:27
One of my colleagues says,
travel broadens the mind
and loosens the bowels.
02:35
And then it's a problem in people
who work in daycare centers.
02:40
And obviously,
it's a problem among food handlers.
02:44
Well, of course, diarrhea is a
pretty common disorder in everybody.
02:49
Most everybody gets an occasional
episode of diarrhea every year.
02:55
And we don't need
medical evaluation for that.
02:59
So when does a
person with diarrhea
actually need to
see a physician?
Well,
that would certainly be for profuse,
watery diarrhea
with hypovolemia.
03:10
In other words,
the patient has such volume depletion,
that when they stand up,
they feel dizzy,
or feel like they're
going to faint.
03:19
Certainly somebody
who has diarrhea along
with definite fever,
say greater than 38.5°C,
or if they've had diarrhea that's
been lasting more than 48 hours,
they probably need
to be evaluated.
03:34
A baby with diarrhea
because they
have such little
blood volume anyway,
need to be evaluated
as do elderly folks.
03:43
And let's say a patient
who has Crohn's disease
or ulcerative colitis,
and they often have diarrhea.
03:50
Let's say they get another
episode of diarrhea.
03:53
Is it the underlying illness?
Or is it some infectious
disease problem,
we need to know and
they need to be evaluated.
04:02
Somebody with
severe abdominal pain,
that is not common in most
benign causes of diarrhea.
04:11
And then someone who has
had recent antibiotic treatment
for any reason there's a concern
for this organism called C. difficile,
which can cause a very severe
form of antibiotic-associated diarrhea,
which can progress to
colitis which can even
progress to toxic
megacolon and death.
04:32
So we need to know if that's there
and that's causing the diarrhea.
04:37
And then the
immunocompromised patient,
the classic example
would be the AIDS patient
with diarrhea because
they may have an
unusual organism
causing their diarrhea,
which requires rather
unusual treatment.
04:52
So more about the clinical
features that we need to discern
what medications the
patient may be receiving.
05:01
For example,
chemotherapy itself.
05:04
If you know about
cancer chemotherapy,
it goes after rapidly
proliferating tissue.
05:11
While the GI tract has
a rapid turnover rate.
05:14
So you can imagine
that diarrhea is a
common complication
of cancer chemotherapy.
05:20
So we need to know
about that kind of history.
05:24
We need to know
about the sexual history.
05:27
We talked about some
of the sexually transmitted
diseases which can be
associated with GI symptoms.
05:35
And we need to know about
whether patients have pets.
05:38
There are some
zoonotic infections
that can be spread
from pets to humans.
05:44
And we need to
know whether patients
are receiving any
kind of medications.
05:49
Now, to figure out what
the cause of the diarrhea is,
it's useful to know
about the onset.
05:58
So if we're talking
about food poisoning,
that usually comes
on pretty rapidly,
usually within 2-7
hours and vomiting
is predominant
in food poisoning.
06:12
And the classic one,
perhaps the most rapid one
is that caused by
staphylococcus,
the enterotoxins
of staphylococcus
comes on faster than about
any form of food poisoning.
06:26
So we need to know about
the recent consumption
of things that might have
staphylococci in them like
chocolate eclairs, like mayonnaise,
like chicken salad,
a t picnics and
things of that nature.
06:43
We need to know about
the duration of symptoms.
06:47
The stool frequency
and the characteristics.
06:50
Is the patient having small volume
stools containing blood and mucus?
That suggests an invasive pathogen.
06:58
We need to know
about the presence of
severe abdominal
pain as we mentioned.
07:03
On physical examination,
we want to look for
evidence of volume depletion.
07:09
For example,
decreased skin turgor,
sometimes it can
be pretty subtle.
07:15
And so what you want to do
with a typical patient is grasp,
say, a centimeter of their skin,
pinch it together
a little gently and
see if it stays up.
07:28
If it sort of tense
that would be
evidence of
decreased skin turgor,
we need to look at the mucous
membranes, are they dry?
The other thing that
a lot of people forget
to check for is
orthostatic hypotension.
07:42
Patient may come in to the emergency
room and they're on a stretcher.
07:46
Well,
we take their blood pressure,
and it might read
120/80 on a stretcher.
07:52
But if you crank the
head of the stretcher up,
say 30°, you may find that the
blood pressure then drops to 90/70,
which is an indication of
orthostatic hypotension,
and rather significant
volume depletion.
08:11
Obviously,
we'll check their temperature.
08:14
And we would hate
to miss something like
acute appendicitis or
other peritoneal signs.
08:21
And by the way, it's hard to
evaluate children for peritonitis.
08:25
But if a child comes in
to the emergency room,
and they won't let
you examine them,
sometimes if you have them
simply jump off a small step.
08:37
If that causes belly pain,
when they jump down one step,
that child may well
have peritonitis.
08:44
Just a little trick for
evaluating toddlers.
08:50
So if they have fever and
peritoneal signs and diarrhea,
then that's usually
indicating invasive bugs
and invasive enteric pathogen.
09:06
So when should you go
ahead and culture the stool?
Well, as I mentioned in
immunocompromised patients,
for example, AIDS, we would want
to know what is growing in the stool.
09:19
Patients who have other
comorbidities particularly diabetics,
patients with ulcerative
colitis or Crohn's disease.
09:28
We need to distinguish
as I mentioned
infection from a
flare of their disease.
09:33
Food handlers may be
required to get a stool culture
to prove that the
pathogen is no longer there,
so that they can return to work.
09:45
Healthcare workers
for the same reason,
it would be sad for a health
care worker to pass on
a cause of diarrhea to
one of their sick patients.
09:56
Same thing goes for daycare
attendees or employees.
10:01
And institutionalized persons
because there are certain
causes of diarrhea that
run rampant in institutions.
10:11
Now, if a physician decides
that a stool culture is indicated.
10:16
It is very helpful to the
laboratory if the physician
will specifically request
culturing for a suspected
pathogen that helps the
lab isolate the right bug.