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We're here at Stanford Medical School with 4th-year medical student Morgan Keyes and Dr. Charles Prober.

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MK: Okay, Dr. Prober, what are we going to talk about today?

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Dr: So Morgan, I thought we'd talk about Bacterial Meningitis in children.

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MK: Okay.

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Dr: And what I'd look to do in reflecting on bacterial meningitis (BC) is...

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...go back to the lessons we learned in the prudent prescribing of antibiotics.

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Dr: a former video, a prior video.

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Dr: One of the things that was mentioned as a general principle in that particular video

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was trying to understand where the site of infection is in a child,

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in order to pick the right antibiotic and the right management.

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Dr: So in this case, since I'm referring to BC, the question might be:

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What would make you think that a child has BC?

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That is, what are the signs and symptoms of BC?

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Student: So this is thinking about the site, knowing that there is an infection in the

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cerebrospinal fluid (CBF), or fluid around the brain and spinal cord, you have to look at that

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in a variety of ways as a doctor?

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Dr: Exactly. One of the things that will make a physician suspicious that there might be

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an infection in the CBF or in the central nervous system (CNS),

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is that a child might not be behaving normally,

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that is, they might have an altered state of consciousness.

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E.g., they might be very, very sleepy; or, they might be very irritable

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Student: So the signs are irritability and/or sleepiness (lethargic),

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maybe even in a coma, which would be more advanced in the infection.

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Dr: And then the child would almost invariably have that fever associated with this illness.

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And, on the examination, when the physician examines the child,

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they might detect what are called "meningeal signs".

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And those meningeal signs include a stiff neck, especially if the child is over 1 or 2 years of age,

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Student: And how can you tell if someone has a stiff neck?

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Dr: What a physician will often due is hold the child behind the head and try

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try to flex the head on the neck, and stiff would be literally that:

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the child's neck would not bend when the head is elevated from the bed.

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Student: Wow, so it's literally where it stays linear, you can't curve it well.

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Dr; Exactly. The other meningeal signs that may be present in addition to the stiff neck are

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the child may have some seizures, abnormal movements.

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The child might also assume an abnormal posture, a stiffening of the body.

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So, not just the neck being stiff, but the rest of the body being stiff as well.

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And on examination of the neurologic system, the nervous system,

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the child might have "focal signs," that is, asymmetry between the two sides of the body.

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Student: Oh, and what kinds of things would you see that are assymetrical?

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Dr: It could be that one side of the body is weaker than the other,

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It could be that one of the body has different reflexes than the other side.

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These are all signs and symptoms which may be associated with BM,

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which would make the physician suspicious of the diagnosis of meningitis.

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Student: Okay, so we talked about some of the things you look for as a doctor. Now,

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going back a minute, you said something about BM, does that assume that there

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are other types of meningitis that we are not addressing in this lecture?

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Dr: That is a very important point. So, I am focusing on BM,

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there are other types of organisms, non-bacteria, that can cause meningitis,

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and the most prominent of those other organisms are viruses.

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So you can have a viral meningitis, sometimes referred to as aseptic meningitis.

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And that in fact is more common that bacterial meningitis, so it is very important to consider.

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There are also some parasites that can cause meningitis, and some fungi.

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The fungi and parasites are uncommon, but they may occur in abnormal immune systems

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Viral meningitis on the other hand is quite common.

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But for today I am focusing on bacterial meningitis.

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So you suspect the infection may be present based on those signs and symptoms.

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To prove, to determine whether meningitis is present,

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a cerebrospinal fluid (CSF) examination [must take place],

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and CSF is acquired by doing a lumbar puncture,

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putting a needle in the back to obtain fluid.

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Student: Is that also what a spinal tap is?

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Dr: That is also called a spinal tap

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When that is obtained, using a needle into the lumbar area,

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a fluid is then sent to the lab, where the fluid will be examined in different ways

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One is to look under the microscope and determine if there is an abnormal number

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of white blood cells present.

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Student: So abnormal meaning high or low?

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Dr: Meaning just high, actually.

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The normal number of white blood cells in the CSF is 0.

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So, high is something greater than 0. And with BM, it tends to be quite high.

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generally 1,000-2,000/mL.

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Glucose is also measured, and with BM the glucose tends to be low

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less than 40.

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Student: Why would it be low?

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Dr: It's low because with meningitis you have an abnormal penetrability,

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or lack of penetrability of the meninges, which are the covers of the brain,

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reducing the amount of glucose that is transported into the spinal fluid.

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Dr: And then most importantly, the fluid is examined with something called the Gram stain,

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a special kind of stain. A Gram stain can determine if bacteria are present.

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Student: So you're actually staining the bacteria.

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Dr: Exactly. And if sufficient bacteria are present the Gram stain will reveal those.

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And so, with BM, the 2nd prudent principle is to know the pathogen.

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So, if a spinal fluid is obtained, there is lots of white cells, your glucose is low,

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even with a negative Gram stain, one can guess the usual pathogens,

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because the list is short in normal children.

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And those bacteria, the short list, includes "Haemophilus influenzae" tybe B,

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2nd, the Pneumococcus.

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Student: That's funny, it sounds like it causes pneumonia.

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Dr: It does cause pneumonia, indeed.

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3rd: Meningicoccus.

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Dr: Those are the prominent bacteria in normal children with BM.

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The reason we're not seeing as much BM in 2011 as we were seeing 10 or 20 years ago,

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is we now have vaccination against each of those three pathogens.

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Student: We do?

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Dr: We do. We vaccinate against "H. Influ. B" starting at two months of age

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and by the time the child is about 1.5yrs, they're completely protected against that bacteria

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The Pneumo we also vaccinate against and it's very successful at reducing

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the frequency of pneumococcal meningitis--also given at 2 months of age.

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And Meningicoccus, the vaccination is relatively new and used in children who are older

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They're now 2yrs of age.

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So, we still can and do see cases of meningicoccal meningitis as it occurs

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in children under the age of 2.

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Those are the usual pathogens. In other parts of the world that don't use vaccines,

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those are the pathogens that will be prominent in causing BM.

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And knowing those pathogens, we go to the 3rd Principle of antibiotic prescribing,

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which is knowing antibiotic would potentially kill those bacteria.

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Student: Okay, so what should I call that category?

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Dr: Pathogen sensitivity, knowing which antibody would work against the likely bug.

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Student: That, you were mentioning in your last lecture,

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that varies by the location in the body, and the location in the world, where you're using it.

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Dr: It varies by the location of the world, but not by part of the body.

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And, fortunately, for the treatment of BM, to cover all three of the bacteria,

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two antibiotics cover all three of them, and I'll just mention the names as I end this.

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One antibiotic is Cefotaxin, and a reasonable facsimile is Ceftriaxone.

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And because some of the Pneumo are resistant to Beta-lactam drugs,

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Vancomycin is also used for suspected BM.

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Student: Okay, so we use Vancomycin if we think you have a bug that is resistant to other drugs?

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Dr: Exactly.

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Student: And there is a type of lab test you could do to find that out?

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Dr: Exactly. So those are the Principles of antibiotic prescribing, in terms of

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diagnosis of BM. 1) Knowing site of infection

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2) What the pathogens are, and 3) knowing what antibiotic would work.

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Student: My last question, just because we learned about a tight barrier between

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the blood and the CSF, are these antibiotics listed here able to cross the barrier?

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Dr: An extraordinarily important question, which is another principle:

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You have to make sure that they can be delivered to the suspected site of infection.

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For those antibiotics, the answer is, "Yes."