Fever & Headache Flashcards
Cardinal meningitis symptoms
Headache Photophobia Neck stiffness Drowsiness -usually present late though
What precedes bacterial meningitis
Colonisation of nasopharynx, 10-20% adults colonised by N. meningiditis
How does bacteria propogate
Through sub arachnoid space - contains wbc’s, cellular debris etc.
Diagnoses of meningitis>
Clinical suspicion, need tests done as signs and symptoms appear late.
Tests done for diagnoses of meningitis
CSF sample
Blood culture
Throat swab
PCR blood tests
What is a manoeuvre used to test for subarachnoid haemorrhage?
Kernigs sign: When leg and knee flexed at 90 degrees, subsequent flexion causes hamstring pain being a positives kernigs sign indicating SA haemorrhage/meningitis.
Steps in Lumbar puncture (CSF sampling):
Foetal position on side. Enter around L2 (below the spinal cord where cauda equina is).
Enter needle between spinous processes in subarachnoid space.
CSF component levels:
Glucose: High in bact. Low in viral - bacteria and neutrophils using up glucose
Protein: High in bact. High/normal in viral - Debris from immune response
WBC’s: High in bact. High in viral
Cells: Neutrophils in bact. Lymphocytes in viral
Gram stain: +/- in bacteria
Culture: ++/- in bacteria
What warrants further molecular investigation?
Serious illnesses or sequelae
Pathogens unable to be cultivated
Improve diagnostic measure
When is further molecular investigation not necessary/useful?
When diagnoses is known
When bacteria can be cultivated
When there is only a small number of pathogens that cause an illness.
When other means are more appropriate.
Classic sign of meningitis?
Pinprick rash!
If no characteristic rash, what next?
ALL EFFORTS TO FIND AETIOLOGY TO EXCLUDE MENINGOCOCCAL DISEASE!
If CSF comes back gram negative - Strep. Pneumoniae antigen test CSF PCR - Pneumoniae vs. Meningiditis Blood PCR - Throat swab - commensal Neisseria Meningiditis
When did the meningococcal epidemic occur in NZ?
1990’s
Implications of influenzae and meningitis both having peak incidence in winter?
Important to tell difference early as meningitis is more serious.
Neisseria Meningiditis virulence factors?
Polysaccharide capsule - Prevents opsinisation
Binds factor H - Down regulates complement cascade
Expresses human LPS on surface - Masks itself from immune system
Secretes LPS - Decoy, keeps complement busy .
