G e n e r a l
O v e r v i e w
Gauhati Medical College
Meningitis is a disease caused by the inflammation of the
protective membranes covering the brain and spinal cord
known as the meninges.
The inflammation is usually caused by an infection of the fluid
surrounding the brain and spinal cord.
Meningitis can be life-threatening because of the
inflammation's proximity to the brain and spinal cord;
therefore the condition is classified as a medical emergency.
The meninges is the system of membranes which envelops the
central nervous system.
It has 3 layers:
1. Dura mater
2. Arachnoid mater
3. Pia mater
Subarachnoid space -
is the space which
exists between the
arachnoid and the pia
mater, which is filled
Causes of Meningitis
- Ricketsial (Rocky mountain spotted fever)
- Parasitic/ protozoal
- Physical injury
- Certain drugs ( mainly, NSAID’S)
Severity/treatment of illnesses differ
depending on the cause. Thus, it is
important to know the specific cause of
- Haemophilus influenzae
- Group A Streptococcus
- Group B Streptococcus
Premature babies and newborns (< 3 months): group B
streptococci, Listeria monocytogenes(serotype IVb).
Older children: Neisseria meningitidis and Streptococcu
pneumoniae (serotypes 6, 9, 14, 18 and 23) and those
under five by Haemophilus influenzae type B
Adults: N. meningitidis and S. pneumoniae (80% of all
cases) of bacterial meningitis, with increased risk of L.
Haemophilus influenzae Meningitis
• Occurs mostly in children (6 months to 4 years).
• Gram-negative aerobic bacteria, normal throat microbiota
• Capsule antigen type b
• Prevented by Hib vaccine
Reduction in H.influenzae meningitis due to development of Hib vaccine
• Gram-negative aerobic
• 10% of people are healthy
• Begins as throat infection, rash
• Serotype B is most common in
the United States
• Vaccination recommended for
Meningitis, Pneumococcal Meningitis
• Gram-positive diplococci
• 70% of people are healthy
• Most common in children (1
month to 4 years)
• Mortality: 30% in
children, 80% in elderly
• Prevented by vaccination
Incubation period : 3 to 6 days.
Duration of the illness : approx 7 to 10 days.
Milder and occurs more often than bacterial
Affects children and adults under age 30. Most
infections occur in children under age 5.
Most viral meningitis is due to enteroviruses, that
also can cause intestinal illness.
Diagnosed by laboratory tests of a patient’s spinal
Symptoms can be the same for Viral and
• Brain damage
• Buildup of fluid between the skull
and brain (subdural effusion)
• Hearing loss
Tests that may be done include:
• For any patient who is suspected of having
meningitis, lumbar puncture ("spinal tap") is done
for CSF examination .
• Blood culture
• Chest x-ray
• CSF examination for cell count, glucose, and
• CT scan of the head
• Gram stain, other special stains, and culture of CSF
• Specimen: CSF, blood, urine culture
• Blood tests and imaging
• Blood tests are performed for markers of inflammation (e.g. C-
reactive protein, complete blood count), as well as blood
• Most important is CSF examination by LP. Blood tests are done
when it is C/I
• In severe forms of meningitis, monitoring of blood electrolytes
may be important; for example, hyponatremia is common in
A lumbar puncture is done by positioning the patient, usually lying on
the side, applying local anesthetic, and inserting a needle into the dural
sac. CT or MRI scan is recommended prior to the lumbar puncture.
The CSF sample is examined for presence and types of white blood cells, red
blood cells, protein content and glucose level. Gram staining of the sample may
demonstrate bacteria in bacterial meningitis (60% cases).
C/I: Mass in the brain (tumor or abscess) or the intracranial pressure (ICP) is
Gram stain of meningococci from a
culture showing Gram negative (pink)
bacteria, often in pairs
CSF findings in different forms of meningitis
Type of meningitis Glucose Protein Cells
Acute bacterial low high
often > 300/mm³
Acute viral normal normal or high
Tuberculous low high
PMNs, < 300/mm³
Fungal low high < 300/mm³
Malignant low high
• Latex agglutination - The clumping of cells such as
bacteria or RBCs in the presence of an antibody. The
antibody or other molecule binds multiple particles and
joins them, creating a large complex. Positive in meningitis
caused by Streptococcus pneumoniae, Neisseria
meningitidis, Haemophilus influenzae, Escherichia
coli and group B streptococci.
• Serotyping - Group of microorganisms classified together
based on their cell surface antigens
(virulence, lipopolysaccharides in Gram-negative
bacteria), presence of an exotoxin or other characteristics
which differentiate two members of the same species.
• Limulus amebocyte lysate (LAL): An aqueous
extract of blood cells (amoebocytes) from the
horseshoe crab, (Limulus polyphemus).
LAL reacts with bacterial endotoxin or
lipopolysaccharide (LPS), which is a membrane
component of “Gram negative bacteria”.
• Polymerase chain reaction(PCR) is a technique
used to amplify small traces of bacterial DNA
Kernig’s sign - is assessed with the patient lying supine, with the hip and knee
flexed to 90 degrees. In a patient with a positive Kernig's sign, pain limits passive
extension of the knee.
Brudzinski signs -A positive Brudzinski's sign occurs when flexion of the neck
causes involuntary flexion of the knee and hip.
Skin findings: Nonspecific blanching, erythematous, maculopapular rash to a
petechial or purpuric rash.
**Approximately 6% of affected infants and children show signs
of disseminated intravascular coagulopathy and endotoxic shock.
These signs are indicative of a poor prognosis.
• Antibiotics for bacterial meningitis :Type vary depending on the
bacteria causing the infection.
• Antibiotics are not effective in viral meningitis.
• Other medications and intravenous fluids will be used to treat
symptoms such as brain swelling, shock, and seizures.
• Haemophilus vaccine (HiB vaccine) in children.
• The pneumococcal conjugate vaccine is now a routine childhood
immunization and is very effective at preventing pneumococcal
• Household members and others in close contact with people who
have meningococcal meningitis should receive preventive antibiotics.