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Current time:0:00Total duration:12:17

Video transcript

we're here at Stanford Medical School with fourth-year medical student Morgan theis and dr. Charles prober okay dr. prober what are we going to talk about today so Morgan I thought we'd talk about bacterial meningitis in children okay 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 former video or prior video okay 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 okay so in this case because I'm referring to bacterial meningitis the 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 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 exactly and one of the things which will make you which wake a physician suspicious that there may be an infection in the cerebral spinal 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 okay so the I guess I would say the signs here irritable children and what was the other one you said and I mentioned they might be very sleepy some people might use the word lethargic as a altered state of consciousness and at the extreme of that the child would be in coma but that would be more advanced in the infection okay and then the child would almost invariably have a fever associated with it will this illness and on examination when the physician examines a child they may detect what are called meningeal signs and those meningeal signs include a stiff neck especially if the child's over one or two years of age and how can you tell if someone has a stiff neck so what the physician will often do is hold the child behind the head and try to flex the head on the neck try to flex the neck and stiff would be literally that that the child's neck would not Bend when the head is elevated from the bed oh wow so it just stays really like linear you know you can't really curve it well exactly the other meningeal signs that may be present in addition to the stiff neck are the child may have some seizures abnormal movements okay the child might also assume an abnormal posture a stiffening of the body so not just the neck 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 would have referred to as focal signs that is asymmetry between the two sides of the body oh and what kinds of things would you see that were a symmetrical 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 and the other side of the body so these are all signs and symptoms that may be associated with bacterial meningitis that would make this the physician suspicious of the diagnosis of meningitis okay 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's other types of meningitis that we're not addressing in this lecture 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 okay sometimes referred to as aseptic meningitis and that in fact is more common than bacterial meningitis so it's very important to consider okay there are also some parasites that can cause meningitis and there's 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 okay viral meningitis on the other hand is really as I mentioned quite common okay 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 a cerebral spinal fluid examination or cerebrospinal fluid has to be examined and cerebral spinal fluid which is typically abbreviated CSF is EPS it stands for cerebral spinal fluid we already got that but okay sorry and that's obtained by doing something called a lumbar puncture by putting a needle in the back to obtain fluid okay um is that also what a spinal tap is and that's also called a spinal tap exactly the lumbar puncture or spinal tap when that's obtained using a needle into the lumbar area the fluid is then sent to the laboratory who will examine the fluid in in different ways okay one is to look under the microscope and determine if there are an abnormal number of white blood cells present so abnormal meaning high or low I mean just okay the normal number of white blood cells in the CSF is zero so high is something greater than zero okay and with bacterial meningitis it tends to be really quite high one or two thousand or more than that okay with viral meningitis it may not be quite as high and that's person unit of volume of this fluid exactly a glucose concentration is also measured when the fluid is sent to the lab and with bacterial meningitis the glucose in this mono fluid tends to be low less than 40 now why would it be low 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 okay and then most importantly the fluid is examined with something called a Gram stain a special kind of stain it's Graham with a capital G named after dr. Graham and a Gram stain can determine whether or not there are bacteria present okay so you're actually staining the bacteria exactly and if there are sufficient bacteria present the Gram stain will reveal those bacteria okay and so with bacterial meningitis they're the second principal prudent principal is to know the usual pathogen 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 hemolysis influenza type B a second bacteria and an that I'm going to eat at the end is an e on the end a second bacteria is the pneumococcus now that's funny it sounds like it causes pneumonia and it does indeed cause pneumonia as well but it also causes bacterial meningitis okay and a third bacteria is called meningococcal and that's those are the prominent bacteria in normal children with bacterial meningitis the reason though we're not seeing 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 all of them we do we vaccinate against a marvelous influenza be 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 okay 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 okay and the ninja caucus is the vaccine is relatively new and is used in children who are a bit older there are over two years of age under special circumstances so that means that we still can see and do see cases of meningococcal meningitis because occurs in children under two years of age I see 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 that what antibiotics typically kill those bacteria okay so what should I call that category like and that's that's catching pathogen sensitivity knowing what what antibiotics work against the likely bug so pathogen sensitivity okay great sensitivity to the antibiotics and and that I think you were mentioning in your 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 I had varies according to the location in the world but not not a nod on what part of the body they're in okay and fortunately for the treatment of bacterial meningitis to cover all three of the bacteria that are on the list of pathogens to antibiotics cover all three of them and I'll just mention their names and as I end this one antibiotic is cefotaxime and a reasonable facsimile of cefotaxime is ceftriaxone and they're very similar antibiotic so we give one or the other of those two antibiotics okay and because some of the pneumococci are resistant to so-called beta lactam drug penicillin and cephalosporins vancomycin also is used to initiate therapy for suspected bacterial meningitis okay so we use vancomycin if we think you have a sort of resistant bugs bugs that are resistant to the first two antibiotics you mentioned exactly and there's some kind of lab tests you might be able to do to find that out exactly so those are the the principles of antibiotic prescribing in terms of the diagnosis of bacterial meningitis knowing the site of infection that is a spinal fluid knowing how to diagnose it what the pathogens are and what antibiotics would work against those pathogens at that site of infection okay and just my last question is just because we've learned a lot about how there's a tight barrier between the blood and the cerebrospinal fluid are these antibiotics that you've listed here those able to sort of penetrate through that barrier and get into the cerebrospinal fluid an extraordinarily important question which back to another principle of antibiotics which is you have to make sure that it can be delivered to the suspected site of infection and for those particular antibiotics the answer is yes okay thank you so much