Bacterial meningitis | Miscellaneous | Heatlh & Medicine | Khan Academy

SAL KHAN: We’re here at Stanford
Medical School with fourth year medical student Morgan Theis
and Dr. Charles Prober. MORGAN THEIS: OK, Dr.
Prober, what are we going to talk about today? DR. CHARLES PROBER:
So Morgan, I thought we’d talk about bacterial
meningitis in children. MORGAN THEIS: OK. DR. CHARLES PROBER:
And what I’d like to do, in reflecting
on bacterial meningitis is go back to some lessons
that we learned in “The Prudent Prescribing of
Antibiotics,” a prior video. And one of the things
that was mentioned as a general principle
in that particular video was trying to understand
where the site of infection is in a child, in order to
pick the right antibiotics and the right management. So in this case,
because I’m referring to bacterial meningitis,
a question might be, what would make you think that a
child has bacterial meningitis? That is, what are the
signs and symptoms of bacterial meningitis? MORGAN THEIS: So this is kind
of thinking about the site, knowing that
there’s an infection in the cerebrospinal
fluid or fluid around the brain
and spinal cord. You have to look for that in a
variety of ways, as a doctor. DR. CHARLES PROBER: Exactly. And one of the things which
will make a physician suspicious that there may be an infection
in the cerebrospinal fluid or that is, in the
central nervous system is, a child may not
be behaving normally. That is, they’ll have an
altered state of consciousness. They’ll be very, very sleepy. Or they’ll be very irritable. MORGAN THEIS: OK, so
I guess I would say, the signs here–
irritable children. And what was the
other one you said? DR. CHARLES PROBER:
And I mentioned they might be very sleepy. Some people might use
the word lethargic, as an altered state
of consciousness. And at the extreme of that,
the child would be in a coma. But that would be more
advanced in the infection. And then, the child
would almost invariably have a fever associated
with it, with this illness. And on examination, when the
physician examines the child, they may detect what are
called meningeal signs. And those meningeal signs
include a stiff neck, especially if the child is
over one or two years of age. MORGAN THEIS: And
how can you tell if someone has a stiff neck? DR. CHARLES PROBER: So what’s
the physician will often do is hold the child
behind the head and try to flex the head on
the next, try to flex the neck. And stiff would
be literally that. The child’s neck
would not bend, when the head is elevated
from the bed. MORGAN THEIS: Oh, wow. So it just stays really linear. You can’t really curve it well. DR. CHARLES PROBER: Exactly. The other meningeal signs that
may be present in addition to the stiff neck
are the child may have some seizures,
abnormal movements. The child might also assume an
abnormal posture, stiffening of the body, so not just
the next being stiff but the rest of the body
being stiff as well. And on examination of
the neurologic system, the nervous system,
the child may have what are referred
to as focal. signs. That is asymmetry between
the two sides of the body. MORGAN THEIS: Oh, and
what kind of things would you see that
were asymmetrical? DR. CHARLES PROBER: It could
be that one side of the body is weaker than the other. It could be that
one side of the body has different reflexes than
the other side of the body. So these are all
signs and symptoms that may be associated with
bacterial meningitis, that would make the physician
suspicious of the diagnosis of meningitis. MORGAN THEIS: OK. So we talked about
some of the things you look for as a doctor. Now, just going back
a minute, you said, we’re talking about
bacterial meningitis. Does that assume that there
are other types of meningitis that we’re not addressing
in this lecture? DR. CHARLES PROBER: That’s
a very important point. So I am focusing on
bacterial meningitis. There are other types
of organisms, that is, non-bacteria that
can cause meningitis. And the most prominent of those
other organisms are viruses. So you can have a viral
meningitis, sometimes referred to as aseptic meningitis. And that, in fact,
is more common than bacterial meningitis. So it’s very
important to consider. There are also some parasites
that can cause meningitis. And there are some fungi
that can cause meningitis. The fungi and
parasites are uncommon in the general
population, but they may occur in patients who have
an abnormal immune system. Viral meningitis,
on the other hand, is really, as I
mentioned, quite common. But for today, I’m focusing
on bacterial meningitis. So you suspect that the
infection may be present, based upon those signs
and symptoms that we’ve spoken about. And then to prove or
determine whether or not meningitis is present,
cerebral spinal fluid has to be examined. And cerebral spinal fluid, which
is typically abbreviated CSF. MORGAN THEIS: CSF is
cerebrospinal fluid. We already got that but OK. Sorry. DR. CHARLES PROBER:
And that’s obtained by doing something called a
lumbar puncture, by putting a needle in the back
to obtain fluid. MORGAN THEIS: OK. Is that also what
a spinal tap is? DR. CHARLES PROBER: And that’s
also called a spinal tap, exactly, a Lumbar
puncture or a spinal tap. When that’s obtained using a
needle into the lumber area, the fluid is then sent
to the laboratory, who will examine the fluid
in different ways. One is to look
under the microscope and determine if there are an
abnormal number of white blood cells present. MORGAN THEIS: So abnormal
meaning high or low? DR. CHARLES PROBER:
Meaning just high actually. MORGAN THEIS: OK. DR. CHARLES PROBER:
The normal number of white blood cells
in the CSF is 0. So high is something
greater than 0. MORGAN THEIS: OK. DR. CHARLES PROBER: And
with bacterial meningitis, it tends to be really quite
high, 1,000 or 2,000 or more than that. With viral meningitis, it
may not be quite as high. MORGAN THEIS: And
that’s per some unit of volume of this fluid. DR. CHARLES PROBER: Exactly. A glucose concentration
is also measured when the fluid is
sent to the lab. And with bacterial meningitis,
the glucose in the spinal fluid tends to be low, less than 40. MORGAN THEIS: Now,
why would it be low? DR. CHARLES PROBER: It’s low
because with meningitis, you have an abnormal penetrability
or lack of penetrability of the meninges, which are
the coverings of the brain, reducing the amount
of glucose that’s transported into
the spinal fluid. And then, most
importantly, the fluid is examined with
something called a Gram stain, a
special kind of stain. It’s Gram with a capital
G, named after Dr. Gram. And a Gram stain can
determine whether or not there are bacteria present. MORGAN THEIS: OK. So you’re actually
staining the bacteria. DR. CHARLES PROBER: Exactly. And if there are sufficient
bacteria present, the Gram stain will
reveal those bacteria. And so with
bacterial meningitis, the second prudent principle
is to know the usual pathogens. So if a spinal
fluid is obtained, there are lots of white
cells, the glucose is low. Even with a negative
Gram stain, one can guess the usual
pathogens, because the list is short in normal children. And those bacteria, the short
list includes a bacteria called Haemophilus
influenzae, type B. MORGAN THEIS: Is
there an A on that? I mean, an E at the end? DR. CHARLES PROBER:
There is an E on the end. A second bacteria is
the new pnuemococcus. MORGAN THEIS: Now, that’s funny. It sounds like it
causes pneumonia. DR. CHARLES PROBER: And it does
indeed cause pneumonia as well. But it also causes
bacterial meningitis. And a third bacteria is
called meningicoccus. And those are the
prominent bacteria in normal children with
bacterial meningitis. The reason though,
we’re not seen as much bacterial meningitis
in 2011 as we were seeing 10 and 20 years ago is,
we now have vaccination against each of those
three different pathogens. MORGAN THEIS: All of them? DR. CHARLES PROBER: We do. We vaccinate against
Haemophilus influenzae, type B, starting at two months of age. And by the time the child
is about a year and a half, they’re completely
protected against that particular bacteria. The pneumococcus, we
also vaccinate against. And it’s very successful. The vaccine is very
successful at reducing the frequency of
pneumococcal meningitis. It also starts at
two months of age. And meningicoccus, the
vaccine is relatively new and is used in children
who are a bit older. They’re over two years of age,
under special circumstances. So that means that
we still can see, and do see, cases of
meningicoccal meningitis, because it occurs in children
under two years of age. MORGAN THEIS: I see. DR. CHARLES PROBER: But those
are the usual pathogens. And when you go to other
parts of the world who don’t use vaccines,
those are the pathogens that will be prominent in
causing bacterial meningitis. And knowing those pathogens,
we go to the third principle of antibiotic prescribing, which
is knowing what antibiotics typically kill those bacteria. MORGAN THEIS: OK. So what should I call that
category, like matching? DR. CHARLES PROBER:
That’s called the pathogen sensitivity, knowing
what antibiotics work against the likely bug,
so pathogen sensitivity. MORGAN THEIS: Pathogen
sensitivity, OK, great. DR. CHARLES PROBER:
Sensitivity to the antibiotics. MORGAN THEIS: And I think
you were mentioning in you last lecture, that varies
by the location in the body and the location in
the world that you’re using the antibiotic. Is that right? DR. CHARLES PROBER:
It varies according to the location in the world. MORGAN THEIS: But
not in the body. DR. CHARLES PROBER: Not in what
part of the body they’re in. And fortunately,
for the treatment of bacterial meningitis,
to cover all three of the bacteria that are
on the list of pathogens, two antibiotics cover
all three of them. And I’ll just mention
their names as I end this. One antibiotic is cefotaxime. And a reasonable facsimile
of cefotaxime is ceftriaxone. They’re very
similar antibiotics. So we give one or the other
of those two antibiotics. And because some of
the new pneumococci are resistant to so-called
beta lactam drugs, penicillin and cephalosporins,
vancomycin also is used to initiate therapy for
suspected bacterial meningitis. MORGAN THEIS: OK. So we use vancomycin
if we think you have sort of
resistant bugs, bugs that are resistant to the first
two antibiotics you mentioned. DR. CHARLES PROBER: Exactly. MORGAN THEIS: And there’s
some kind of lab tests you might be able to
do to find that out. DR. CHARLES PROBER: Exactly. So those are the principles
of antibiotic prescribing, in terms of the diagnosis
of bacterial meningitis– knowing the site
of infection– that is, the spinal fluid–
knowing how to diagnose it, what the pathogens, and
what antibiotics wold work against those pathogens
at that site of infection. MORGAN THEIS: OK. And just my last
question is, just because we’ve learned
a lot about how there is a tight barrier
between the blood and the cerebrospinal
fluid, are these antibiotics that you’ve listed here– are
those able to sort of penetrate through that barrier and get
into the cerebrospinal fluid? DR. CHARLES PROBER: An
extraordinarily important question, which got to another
principle of antibiotics, which is, you have to make sure
they can be delivered to the suspected
site of infection. And for those
particular antibiotics, the answer is, yes. MORGAN THEIS: OK. Thank you so much.

17 comments

  1. Great lecture. Would consider changing the background to dark black – the lighter one is distracting. Thankx for the info.

  2. Guys: she is asking "leading" questions, so that he can explain it to you. Its a lecture technique. She already knows the answers, you may not, so she is asking teh questions you would ask.

  3. Thanks so much for the info. 👍
    Don't be ungrateful guys. She's asking questions you would ask so that he can explain it. Of course she knows the answers already. Be grateful for the info and move on.

  4. Thank you for the great videos.

    P.S. As far as I know glucose is low in bacterial meningitis because of the fact that the bugs are eating it.

  5. Thank you for the information, proving to be very useful in finding out what I need to know to write my research paper: Bacterial Meningitis in Children for my medical terminology course! Cheers!! ~

  6. gdevening sir,my son was diagonised with meningeoncephalitis when he was 9mnths 2weeks old which he is recovering well. though he is going through physiotherapy, I need to know how long it will take for him function normal again: to sit, stand,walk,talk etc. he is 1year 3months old now. he was sick 28 of february and was discharged 3months later.

  7. my son had a miningitis its started from 5 months of age he had a abnormal possition,shiff neck,but his not like ds before..and now he is 1 year and 1 month…what should i need to do..to back him to the normal?

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