In our discussion of
Gastrointestinal Tract Infections,
we come to the very large topic of
Infectious Diarrhea and Food Poisoning.
We would certainly define it as the
acute onset of excessive bowel movements
caused either directly or
indirectly by microbial pathogens.
It's got a tremendous
impact on the world.
It's the second leading cause
of morbidity and mortality
with 3 million deaths a year.
And that's more than 8400 a day.
And unfortunately it affects our young
children in developing countries.
And main reason for that is that they
don't have a lot of fluid to start with
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.
Diarrhea is a thousandfold
higher in developing countries
than in the United States.
But it still is a problem in the United
States with 179 million cases a year,
17 million of which
about 2 million of those
instances require hospitalization.
Three thousand deaths
is a sizable amount
and most of the deaths
occur among elderly persons.
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.
The annual incidence per 100,000 people
of domestically acquired bacterial
and parasitic infections in 2019 in 10
US sites is shown in this histogram.
Compylobacter leaves the list,
followed closely by Salmonella,
then Shiga toxin-producing E.
Coli or STEC, Shigella,
Cylospora a parasite,
Yersinia, Vibrio and Listeria.
Then as far as the causes
of acute bacterial diarrhea,
if you're talking about
we're talking about
E. coli, the cause of Turista.
Some people call it
some people call it the
green apple quick step.
There are many names for it.
One of my colleagues says,
"Travel broadens the mind
and loosens the bowels."
And then it's a problem in people
who work in daycare centers
and obviously it's a
problem among food handlers.
Well, of course, diarrhea is a
pretty common disorder in everybody.
Most everybody gets an occasional
episode of diarrhea every year
and we don't need medical
evaluation for that.
So when does a person with diarrhea
actually need to see a physician?
Well, that would certainly be for
perfused watery diarrhea with hypovolemia.
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.
Certainly, somebody who has
diarrhea along with definite fever,
say greater than 38.5 Celsius
or if they've had diarrhea that's
been lasting more than 48 hours,
they probably need
to be evaluated.
A baby with diarrhea because they
have such little blood volume anyway,
need to be evaluated
as do elderly folks.
Let's say a patient who has Crohn's
disease or ulcerative colitis
and they often have diarrhea,
let's say they get another
episode of diarrhea.
Is it the underlying illness or is
it some infectious disease problem?
We need to know and they
need to be evaluated.
Somebody with severe
that is not common in most
benign causes of diarrhea.
And then someone who has had
recent antibiotic treatment
for any reason
there is a concern
for this organism called
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.
So we need to know if that's there
and that's causing the diarrhea.
And then the immunocompromised patient,
a classic example would be the AIDS patient
with diarrhea because they may have an
unusual organism causing their diarrhea
which requires rather
So, more about the clinical
features that we need to discern
what medications the
patient may be receiving.
If you know about cancer chemotherapy,
it goes after rapidly proliferating tissue.
Well, the GI tract has
a rapid turnover rate.
So you can imagine that diarrhea is a
common complication of cancer chemotherapy.
So we need to know about
that kind of history.
We need to know about
the sexual history.
We talked about some of the
sexually transmitted diseases
which can be associated
with GI symptoms.
And we need to know about
whether patients have pets.
There are some zoonotic infections
that can be spread from pets to humans.
And we need to know whether patients
are receiving any kind of medications.
Now, to figure out what the
cause of the diarrhea is,
it's useful to know
about the onset.
So if we're talking
about food poisoning,
that usually comes on pretty
rapidly, usually within 2 to 7 hours.
And vomiting is predominant
in food poisoning.
And in classic one, perhaps the most rapid
one, is that caused by Staphylococcus.
comes on faster than about
any form of food poisoning.
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
at picnics and things of that nature.
We need to know about
the duration of symptoms,
the stool frequency and
Is the patient having small volume
stools containing blood and mucus?
That suggest an
We need to know about the presence of
severe abdominal pain as we mention.
On physical examination, we want to
look for evidence of volume depletion,
decreased skin turgor.
Sometimes it can
be pretty subtle,
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.
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.
Patient may come in to the emergency
room and they're on a stretcher.
Well, we take their blood pressure and
it might read 120/80 on a stretcher.
But if you crank the head of the
stretcher up, say 30 degrees,
you may find that the blood
pressure then drops to 90/70,
which is an indication of
and rather significant
we'll check their temperature
and we would hate to miss
something like acute appendicitis
or other peritoneal signs.
And by the way it's hard to
evaluate children for peritonitis.
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.
If that causes belly pain
when they jump down 1 step,
that child may well
Just a little trick for
So, if they have fever and
peritoneal signs and diarrhea,
then that's usually
indicating invasive bugs
and invasive enteric pathogen.
So when should you go ahead
and culture the stool?
Well as I mention in
for example AIDS, we would want to
know what is growing in the stool.
Patients who have other
comorbidities particularly diabetics,
patients with ulcerative
colitis or Crohn's disease,
we need to distinguish, as I mention,
infection from a flare of their disease.
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.
for the same reason.
It would be sad for
a healthcare worker
to pass on a cause of diarrhea
to one of their sick patients.
Same thing goes for daycare attendees or
employees and institutionalized persons
because there are certain causes of
diarrhea that run rampant in institutions.
Now, if a physician decides that
a stool culture is indicated,
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.