Bacterial Meningitis Flashcards
Describe bacterial meningitis
This is considered a medical, neurologic and sometimes neurosurgical emergency
The incidence varies throughout the world with it being rare in the west and much more common in the meningitis belt of Africa

What is meningitis?
Infection of the meninges – membranes that line the brain and spinal cord
What things cause acute meningitis, marked by quick onset, and a quick progression?
bacteria and viruses
As opposed to TB/Crypto (subacute).
How does meningitis occur?
Following colonization (commonly of the mucous membranes of the respiratory tract), there is invasion into the bloodstream and eventual entry into the subarachnoid space (Direct spread to the CNS also occurs after sinusitis and otitis media)
Subsequent inflammation and neurological damage ensues
Why is the CNS so susceptible to inflammation and neurological damage?
- Subarachnoid space has lack of host defenses
- Bacterial components recognized, cytokines (TNFα, IL-6, and IL-1) released
- Neutrophils then cross the BBB and bacterial lysis occurs leading to release of more pro-inflammatory agents
T or F. Many cytokines are released in greater quantity in pneumococcal meningitis than in meningitis caused by other organisms
T. and could account for the worse prognosis associated with pneumococcal meningitis.

What are the classic symptoms of meningitis?
Fever, nuchal rigidity, and AMS (occurs in <50%)
–Any 2 of HA, nuchal rigidity, fever or AMS much more common – up to 95% of patients
What are some other findings with bacterial meningitis?
vomiting, photophobia, seizures, focal neurologic deficit (eg. Cranial nerve palsies), papilledema
Petechiae and purpura are classic with meningitis due to what organism?
N. meningitidis
What is a Brudzinski sign?
with patient in supine position, passively flex head towards the chest. Test is positive when there is flexion of the knees and hips.
Tests are not good. Kernig and Brudzinski: 5% sensitivity for meningitis
What is a Kernig sign?
–patient is supine with hip flexed at 90°. Attempt to extend the leg at the knee. Test is positive when there is resistance to extension a the knee or pain in lower back or posterior thigh
.
What is Jolt accentuation of HA?
–Jolt accentuation of HA: patient rotates his/her head horizontally 2-3 times per second. Test is positive if patient reports exacerbation of headache
Jolt accentuation: conflicting studies. Initially looked better but more recent study showed sensitivity of 21%
How is bacterial meningitis diagnosed?
Most important and should be done as soon as possible: Lumbar puncture for CSF (gold standard). Should be done before antibiotics if possible.
Other options: routine labs (elevated WBC count, possible thrombocytopenia, possible DIC), blood cultures (especially if LP is delayed until after ABX have been given)
_____% of patients with bacterial meningitis will have positive blood cultures
50-90%
Sometimes if there is a possibility of a mass lesion or increased ICP, head CT is indicated prior to LP being done for diagnosies. If not and there is increased ICP, LP could cause brain herniation.
Reasons for obtaining head CT prior to LP:
Immunocompromised state (eg, HIV infection, immunosuppressive therapy, solid organ or hematopoietic stem cell transplantation)
●History of central nervous system (CNS) disease (mass lesion, stroke, or focal infection)
●New onset seizure (within one week of presentation)
●Papilledema
●Abnormal level of consciousness
●Focal neurologic deficit

What CSF findings suggest bacterial meningitis?
–High opening pressure (normal 10-20 cm H2O)
–High WBC (neutrophil predominant) (chemotactic response) (normal 0-5)
–High protein (blood-brain-barrier breakdown) (normal 15-45)
–Low glucose (host stress response) (normal is 2/3 the plasma glucose)
Bacterial meningitis example:
Opening pressure 30 cm water
WBC 100-50,000
Protein 150
Glucose 30 (serum glucose 100)
How sensitive are CSF gram stain and culture for bacterial meningitis?
Gram stain sensitivity 65-80%, culture about 80% sensitive
What are the most common causes of bacterial meningitis in newborns (less than 1 month)?
GBS
E. Coli
Listeria
What are the most common causes of bacterial meningitis in children 1-23 months old?
S. pneumo
N. meningitis
H. influenzae
GBS, E. Coli, Enteroviruses
What are the most common causes of bacterial meningitis in people 2-50 yo?
S. pneumo
N. meningitidis
Enteroviruses
HSV
What are the most common causes of bacterial meningitis in people 50+ yo?
S. pneumo
Aerobic Gram negative rods
Listeria
N. meningitidis







