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 are food-borne,
about 2 million of those instances require hospitalization.
Three thousand deaths is a sizable amount
and most of the deaths occur among elderly persons.
And if you tally the cost, it's 6 billion in medical care
and lost productivity every year.
So, if you're talking about organisms per 100.000 population,
Salmonella leads the list, followed by Campylobacter,
shiga toxin-producing E. coli, Vibrio and Yersinia. So Salmonella
is quite a big problem in the United States. More about that later.
Then as far as the causes of acute bacterial diarrhea,
if you're talking about international travel,
we're talking about these organisms. E. coli, the cause of Turista.
Some people call it Montezuma's revenge,
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 abdominal pain,
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 Clostridium 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.
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 unusual treatment.
So, more about the clinical features that we need to discern
what medications the patient may be receiving.
For example, chemotherapy itself.
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.
The enterotoxins of 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 the characteristics.
Is the patient having small volume stools containing
blood and mucus? That suggest an invasive pathogen.
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, for example, 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 orthostatic hypotension
and rather significant volume depletion.
Obviously, 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 have peritonitis. Just a little trick for evaluating toddlers.
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 immunocompromised patients, 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.
Healthcare workers 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.