Meningitis Flashcards
Define meningitis.
Life-threatening inflammation of the meninges caused by various bacteria/viruses
What are the risk factors for meningitis?
- <5 or >65years
- Crowding
- Exposure to pathogens
- Non-immunised infants - Haemophilus influenzae type b, pneumococcal, or meningococcal meningitis
- Immunodeficiency
- Asplenia/hyposplenic state e.g. SCD
- Cranial anatomical defects/VP shunts
- Cochlear implants
- Contiguous infection - inusitis, pneumonia, mastoiditis, and otitis media.
What pathogens is each of these associated with?
Neonates
- Group B streptococcus – GBS is found in the vaginal canal. When giving birth, especially in long vaginal delivery you are likely to pass it on. Usually it is tested for and prophylactic antibiotics give.
- E coli –
- Listeria monocytogenes – less likely
Children and teenagers
- Neisseria meningitidis
- Haemophilus influenzae (vaccination at about 3 months old)
Adults and elderly
- Streptococcus pneumoniae
- Listeria monocytogenes
What bacteria most commonly cause meningitis?
- Neisseria meningitidis (meningococcal meningitis)
- Streptococcus pneumoniae (pneumococcal meningitis)
- Haemophilus influenzae type b (Hib meningitis)
Others: Listeria, GBS, E coli
Which viruses can commonly cause meningitis?
- Enteroviruses are most common cause
- Measles
- West Nile virus
- Herpes viruses (HSV2)
- Varicella zoster
- Mumps
What are the most common causes of aseptic meningitis?
80-90% are viral
- Enteroviruses - e.g. Coxsackie group B or Echoviruses
- Herpes simplex (1&2)
What are the rash presentations in N. meningitidis?
Non-blanching rash (80%) - usually confirms that the cause is Neisseria meningitidis
Maculopapular (13%)
No rash (7%)
*% relate to presentation in children.
What are the early features of meningitis?
- Headache
- Fever
- Leg pains
- Cold hands and feet
- Abnormal skin colour
What are the later features of meningitis?
- Meningism ***
- Low GCS, coma
- Seizures (~20%) +/- focal CNS signs (~20%) ± opisthotonus
- Petehial rash (non-blanching, 1 or 2 spots or none)
- Shock: prolonged capillary refill time, DIC, reduced BP
What investigations would you do for meningitis?
- LP - CSF cell count and differential, protein, glucose, MC&S, antigen detection
- Blood culture (x2)
- Blood/CSF PCR - good if antibiotics already given
- MRI>CT head scan - MRI better for CNS infections; brain infarction, cerebral oedema, and hydrocephalus are common findings especially in pneumococcal meningitis.
- Throat swab - one for bacteria and another for viruses
Other:
- CRP, FBC, coagulation screen
- VBG - lactate >4mmol/L indicates shock
- U&Es - may show acidosis
- Other investigations, LFT, glucose. CXR. Consider HIV, TB tests.
What is the opening pressure in bacterial meningitis? How much CSF is needed?
_>_20cmCSF or higher
At least 15ml needed for investigation
When should you delay LP in meningitis?
Shock
Sepsis or rapidly progressing rash
Severe respiratory or cardiac compromise
Confirmed/known bleeding or high risk of bleeding
Raised intracranial pressure, indicated by:
- Focal neurological signs
- Papilloedema
- Continuous or uncontrolled seizures
- Glasgow Coma Scale score ≤12.
NB: still give antibiotics
What are the differences between CSF is bacterial, viral and TB/fungal infection?
Normally CSF is CLEAR, low WCC, normal proteins, glucose, negative gram stain
Bacteria CSF is RURBID, high WCC (neutrophils AKA polymorphs), high protein (because neutrophils enter first which count as proteins), low glucose, positive gram stain
Viral CSF is CLEAR/cloudy, high WCC (lymphocytes), high protein (not as high), glucose normal (viruses don’t consume glucose), no gram stain
TB/fungi – CLEAR/cloudy, high WCC (lymphocytes), high protein, slightly low glucose (because some used for respiration).
What is Kernig’s sign?
Kernig’s sign: with the patient supine and the thigh flexed to a 90° right angle, attempts to straighten or extend the leg are met with resistance.
Positive in meningitis
What is Brudzinski’s sign?
Brudzinski’s signs: flexion of the neck causes involuntary flexion of the knees and hips, or passive flexion of the leg on one side causes contralateral flexion of the opposite leg.
Positive in meningitis
What condition frequently co-exists with meningitis?
Septicaemia
- 50% have meningitis,
- 7-10% have septicaemia,
- 40% have meningitis AND septicaemia
What is the triad of meningism?
- Nuchal rigidity (neck stiffness),
- Photophobia (intolerance of bright light)
- Headache
How do you manage meningitis?
In hospital:
Early antibiotics. Take cultures first. Then LP prior to antibiotics only in patients where no evidence of shock, petechial rash or ↑ICP and where able to obtain LP within 1h
Prophylaxis - given to close contacts e.g. rifampicin/ciprofloxacin
Report to public health
In community:
IM benzylpenicillin in the community or IV if access established (for N. meningitidis)
Call 999, lie the patient down and give oxygen.
IV ceftriaxone (for cause other than N.meningitidis)
Describe the CSF analysis in bacterial meningitis.
Describe CSF analysis in viral meningitis.
What is the normal WCC, protein and glucose content in CSF?
- ≤5 lymphocytes/mm3 with no neutrophils is normal.
- Protein: 0.15–0.45g/L.
- CSF glucose: 2.8–4.2mmol/L.
Signs of disease causing meningitis:
Zoster; cold sore/genital vesicles (hsv); hiv signs (lymphadenopathy, dermatitis, candidiasis, uveitis); bleeding ± red eye (leptospirosis); parotid swelling (mumps); sore throat ± jaundice ± nodes (glandular fever); splenectomy scar (∴ immunodeficient)
What is the antibiotic of choice for meningitis? What if there is confusion?
Meningitis
- Ceftriaxone 2g IV BD -
- If >50yrs or immunocompromised → ADD amoxicillin 2g IV 4hourly
Meningo-encephalitis
- Acyclovir 10mg/kg IV TDS
- Ceftriaxone 2g IV BD
- If >50yrs or immunocompromised → ADD amoxicillin 2g IV 4hourly
What is the management of aseptic meningitis?
Self-limiting disease that resolves in 1-2 weeks
Which abx are suitable for chemoprophylaxis?
Rifampicin
Ciprofloxacin
Ceftriaxone
What is the purpose of chemoprophylaxis in meningitis contacts?
Eliminate CARRIAGE
not to prevent illness in those already infected
Which meningitis organisms are notifiable?
- Haemophilus influenzae (invasive)
- Streptococcus pneumoniae (invasive)
- Neisseria meningitidis
Other:
- Listeria monocytogenes
- Legionella species
- Shigella species
- Streptococcus pyogenes (invasive)
- Escherichia coli
- Mycobacterium tuberculosis
When should you follow up meningitis patients after discharge?
6 weeks
What is the pathophysiology of bacterial meningitis?
Bacteria reach CNS by haematogenous spread or direct extension from contiguous site.
Bacteria multiply quicker once in subarachnoid space –> inflammatory mediators, influx of leukocytes –> cerebral oedema and increased ICP
What is the pathophysiology of viral meningitis?
- Viral penetration of BBB occurs by infection of endothelial cells or migration of leukocytes
- HSV may spread by haematogeous spread or retrograde spread along peripheral nerves
- Once in subarachnoid space, viruses may go on to infect neurons and glial cells leading to encephalitis or myelitis.
Is meningococcal septicaemia notifiable?
Yes - all meningococcal disease should be reported
Should steroids be given in meningitis?
Only given by a specialist as they have benefits in reducing cerebral oedema.
What are the complications of meningitis?
- 10% mortality
- 5% neurological sequelae e.g. sensorineural deafness (most common in pneumococcal meningitis)
- elevated ICP
- hydrocephalus
- cognitive, academic and behavioural problems
- seizures
- subdural effusion
- septic DVT
What is the prognosis in meningitis?
With quick and adequate treatment the prognosis is excellent
