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Meningitis and Sepsis
Meningitis
Meningitis is one of the most serious infections you can have. It is also one of the scariest -- understandably, since
untreated some forms of meningitis can cause death or lasting impairment.
The meninges are membranes that enclose the brain and spinal cord. There are actually three layers of membrane: the
"dura", which is a tough outer layer, the "arachnoid", which is a lacy, web-like middle layer, and the "pia", which is a
delicate, fibrous inner layer containing many of the blood vessels that feed the brain and cord.
Meningitis, strictly speaking, is an inflammation of the meninges. (The suffix "-itis" stands for "inflammation";
inflammation of the brain tissue itself is called "encephalitis", where "encephal-" refers to the brain tissue.) There are
many causes for inflammation of tissue, and the meninges are no exception. However, the most common cause of
meningeal inflammation is irritation caused by infection with bacteria or viruses. These organisms usually enter the
meninges through the bloodstream from other parts of the body. As a matter of fact, many meningitis-causing bacteria are
carried in the nose and throat, often without the carrier having symptoms.
Viral meningeal infections are usually (but not always) as severe as bacterial infections. This is quite fortunate, since
there are no antibiotic treatments available for most viruses and we must therefore let viral meningitis run its course by
itself. Bacterial meningitis, on the other hand, must be treated with antibiotics in most cases to avoid severe
consequences. Unfortunately the only way to confirm that meningitis is not bacterial is to culture the spinal fluid (actually
the cerebrospinal fluid, since it bathes both the spinal cord and the brain) and see if there are bacteria in it. This can take
3-5 days. Since a bacterial meningitis can do a LOT of damage in 3-5 days, a common practice is to start antibiotics
immediately after doing the spinal tap and keep giving the antibiotics until the culture has shown no bacteria for 3-5 days.
This may seem wasteful (especially to bean-counters), but it is far better to treat all suspected meningitis patients
promptly than to have to treat the long-term consequences of an untreated meningitis.
Since inflammation and resulting swelling seem to be the main cause of brain damage from meningitis, steroids have
been used in some cases to help lessen the inflammation. Steroids usually are given along with antibiotics, and may not
be apropriate in all cases of meningitis.
Sepsis
"Sepsis" is the term we use for an overwhelming bacterial infection. Sepsis usually includes "bacteremia", or bacteria in
the blood, although bacteremia can happen without sepsis (you will have bacteria in your blood briefly every time you
brush your teeth...). Usually we reserve the term "sepsis" for patients whose infections are so severe that they are in
shock; such infections happen more often when the immune system isn't working quite right (because of cancer, AIDS,
or malfunctioning organs or bone marrow, or other diseases). Very young babies do not have fully functional immune
systems either and are thus susceptible to sepsis; this is why we routinely give IV antibiotics to any child under 2 months
old who has a fever -- we cannot risk leaving sepsis untreated.
Among common bacterial causes of meningitis and sepsis are:
Neisseria menigitidis (Meningococcus)
Meningococcus is a bacteria often carried in the nose and throat without symptoms. It can be spread by droplets coughed
or sneezed out by an infected person or by a carrier; many outbreaks of meningococcal infection occur in people living in
close quarters (schools, colleges, and military installations, for example). It takes 1-10 days (most often 4 days or less)
after exposure to show symptoms; patients are usually contagious until they have been treated for at least 24 hours.
Meningococcal infection can cause meningitis, sepsis, or both. Oddly, someone with meningococcal infection with
meningitis may do better than s/he would with sepsis and no meningitis; this does not always happen, though. Signs of
meningococcal infection may include fever with chills and a rash; the classic rash of meningococcal infection is
"petechial", caused by tiny blood clots just below the skin surface. In severe cases the infection can result in shock and
death within a few hours even if treated.
In the past penicillin G has been sufficient treatment for meningococcal infection. However we have seen strains of
meningococcus in recent years that are resistant to penicillin G; these require treatment with other antibiotics such as the
third-generation cephalosporins. Antibiotics for someone with possible meningococcal infection are chosen initially
according to whether or not resistance has been seen in previous patients with meningococcus, since there may not be
enough time to culture the patient's own bacteria and test different antibiotics against it.
There are many different groups or "serotypes" of meninigcocci, at least 8 of which can infect people. The most common
infectious groups are labelled A, B, C, X, Y, Z, 29-E, and W-135 (and no, I don't know exactly how the labels were
assigned...). Groups B and C are the groups most often seen in the United States. Unfortunately we do not yet have a
good vaccine for group B. There is, however, a vaccine available that protects against groups A, C, Y, and W-135 (it is
actually a combination of vaccines against each of the 4 groups); it is usually given in a single dose, although it may have
to be given in two doses to children younger than 18 months. The A vaccine will provide immunity to patients 3 months
or older, but the C component is effective in children 2 years or older. We do not routinely vaccinate children against
meningococcus in the United States, but travelers to countries where meningococcus is more common should receive the
vaccine, as should patients whose spleens have been removed or no longer work properly (such as patients with
sickle-cell anemia, whose spleens eventually fail). Certain groups of people, such as military personnel, routinely receive
the vaccine.
Streptococcus pneumoniae (Pneumococcus)
Pneumococci are even more common than meningococcus; in fact pneumococci are the most common cause of ear
infections and sinus infections, as well as the most common bacteria found in the blood of children under 2 years old
with fevers, many of whom have no obvious site of infection. Again, like meningococcus, many people have
pneumococci in their noses and throats but have no symptoms. The bacteria is transmitted from one person to another,
usually by droplets. Like viral upper respiratory infections, pneumococcal infections are more common in winter.
Infection can begin as little as 1-3 days after exposure.
The signs of pneumococcal meningitis and sepsis can be the same as those of meningococcal meningitis. Often,
however, pneumococcal infection can appear first as a high fever with a very high white-blood-cell count (where almost
all of the white cells are neutrophils or bacteria-fighting cells) and no obvious site of infection.
again, like meningococcus, pneumococcal infections could be treated with penicillin G, but penicillin-G-resistant
pneumococci have become more and more common, especially with antibiotic overuse (this is one reason why we use so
many different antibiotics to treat ear infections). We usually start meningitis or sepsis treatment with third-generation
cephalosporins such as ceftriaxone, until the cultures have been completed and we know what antibiotics can be used.
There are over 80 different know serotypes of pneumococcus. Some are more prevalent in different areas; some are more
prevalent in children, while others are more common in adults. There is a vaccine available that protects against 23 of the
known serotypes; as with meningococcus, the vaccine is given mainly to those at risk of severe infection, including those
whose spleens no longer work properly. The vaccine does not provide complete protection, and vaccine-induced
immunity does not necessarily last for a lifetime. (Pneumococcal vaccine, by the way, will not necessarily help prevent
ear infections, either, and is usually not given to children to prevent otitis.)
Viral Meningitis
Although it is quite possible to have an overwhelming viral infection, generalized viral infections are common enough --
and usually not dangerous enough -- that we don't often consider viral sepsis as a separate problem. (Besides, we have
no antibiotics to treat most viral infections, anyway.)
However, viral meningitis is a separate problem, and a common one at that. We can't treat viral meningitis either, but
viral meningitis is usually less severe and causes less damage than bacterial meningitis. (I had a viral meningitis myself as
a teenager. I may not be quite normal, but it doesn't seem to have done too much damage...)
Many commmon viruses can cause meningitis. Among these are enteroviruses (like the polio viruses), varicella (the
chickenpox virus), the mumps virus, and many others. Notice that many of these viruses are ones we have vaccines for;
a child who has been properly immunized against these viruses will likely not develop meningitis from them. The only
treatment for viral meningitis is supportive: we try to keep the patient comfortable and support vital functions as needed.
The Rhode Island Meningitis Outbreak
Early in Spring, 1998, three children in Rhode Island died of meningitis, and -- not unreasonably -- many parents were
concerned about the possibility of their children contracting meningitis. I had a couple of inquiries from Rhode Island
parents regarding the problem, and according to news reports Rhode Island doctors were deluged with phone calls.
Many parents sought vaccination against meningococcus (the apparent organism responsible for most of the cases in the
outbreak) for their children.
The meningococcus vaccine, as I described above, protects against four of the known serotypes of meningococcus -- and
does NOT protect against type B, the most common type. Also, the vaccine does not work well in children younger
than 2 years. It isn't a bad idea to vaccinate 2-year-olds and older children against meningococcus IF they have been
exposed to a person with proven meningococcus, along with antibiotics to kill any meningococcus they might have in
their noses and throats. However, mass immunization against meningococcus may not be necessary if meningococcus is
not the cause of the meningitis outbreak, or if you live far from the reported cases. As always, you should talk to your
doctor about the vaccine and its pros and cons before deciding whether to get it for your children or yourself.
Back to the Infections and Immunizations Index
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We welcome your comments and questions.
PLEASE NOTE: As with all of this Web site, I try to give general answers to common questions my patients and
their parents ask me in my (real) office. If you have specific questions about your child you must ask your child's
regular doctor. No doctor can give completely accurate advice about a particular child without knowing and examining
that child. I will be happy to try and answer general questions about children's health, but unless your child is a
regular patient of mine I cannot give you specific advice.
Copyright © 1998 Vinay N. Reddy, M.D. All rights reserved.
Written 02/14/98; last revised 09/18/98 |
