Meningitis (N) Flashcards
Define meningitis.
Infection of the meninges in the brain or spinal cord, that is most commonly bacterial or viral in origin, but may also be fungal, parasitic or due to non-infectious causes
Describe the aetiology of meningitis.
Inflammation of pia and arachnoid mater due to infection –> immune response causes cerebral oedema and increased intracranial pressure leading to:
- herniation
- raised ICP and systemic hypotension, reducing cerebral perfusion
What demographics does meningitis tend to happen in most commonly? (2)
- children <1y
- median age in adults = 43
Which bacteria causes meningitis in neonates?
Group B Streptococci
Which bacteria cause meningitis in children and adults? (3)
- Neisseria meningitidis - gram -ve diplococci (also causes petechial non-blanching rash, most DANGEROUS)
- Streptococcus pneumoniae - gram +ve diplococci (most common in ADULTS)
- Haemophilus influenzae
Which bacteria cause meningitis in the elderly?
Streptococcus pneumoniae (and Listeria monocyogenes)
What are the viral causes of meningitis? (5)
- enteroviruses - most common cause (poliovirus, Coxsackie A&B)
- HSV
- VZV
- mumps
- HIV
What is a fungal cause of meningitis?
Cryptococcus (common in HIV patients)
What are some other forms of meningitis? (2)
- aseptic meningitis
- Mollaret’s meningitis
What is the predominant causative organism of meningitis?
Neisseria meningitidis
What is the similarity/difference between bacterial and viral meningitis?
Features are similar, although viral meningitis is less acute and usually self-limiting
What are the clinical features of meningitis? (10)
- fever
- headache (early)
- neck stiffness (late)
- photophobia
- irritability
- nausea and vomiting
- altered mental status
- seizures (more in encephalitis)
- deafness
- non-blanching petechial rash (late, more likely due to N. meningitidis)
What might you see on examination of meningitis? (2)
- Kernig sign - inability to straighten leg when hip is flexed to 90 degrees
- Brudzinski sign - forced flexion of neck elicits a reflex flexion of hips AND knees
What are the signs of meningism? (4)
- stiff neck
- photophobia
- Kernig’s sign
- Brudzinski’s sign
What signs of infection might you see in meningitis? (5)
- fever
- tachycardia
- hypotension
- skin rash
- altered mental state
What is a sign you would see in meningococcal sepsis?
Non-blanching rash
What are the clinical features of meningitis in neonates? (7)
- no classic triad of fever, headache, neck stiffness
- lethargy
- irritability
- poor appetite
- vomiting
- fontanelle bulging
- seizures
What is the classic triad of meningitis?
Fever + headache + neck stiffness
How does fungal meningitis present?
Onset of headache and fever over weeks/months
What are the risk factors for meningitis? (7)
- immunocompromised
- crowded living conditions
- otitis media, inner ear infections, mastoiditis
- sinusitis
- CSF leak after head trauma/neurosurgery
- sepsis
- alcoholism
What are the 1st-line investigations for meningitis? (5)
- lumbar puncture
- blood culture
- serum pneumococcal and meningococcal PCR
- blood glucose
- FBC and differential
What is the main investigation needed for meningitis?
Lumbar puncture for CSF analysis (only if no signs of raised ICP)
When is lumbar puncture done for suspected meningitis?
Usually done after CT - but if GCS15, no symptoms of raised ICP and focal neurology –> can be done without CT to save time
What would bacterial-meningitis CSF show? (4)
- cloudy
- very high neutrophils (polymorphonuclear cells)
- very high protein
- very low glucose (typically <50% serum glucose)
What would viral-meningitis CSF show? (5)
- clear
- high lymphocytes
- high protein
- normal glucose
- normal opening pressure
What would TB-infected CSF show? (5)
- clear/cloudy/fibrin web
- high lymphocytes
- high protein
- low glucose
- high opening pressure
What are normal and elevated opening pressures of CSF in meningitis?
- 7-18cm CSF if normal
- may be >40 in meningitis
What are some contraindications for lumbar puncture in meningitis? (7)
- raised ICP
- suspected intracranial mass lesion
- focal neurological signs
- papilloedema
- trauma
- middle ear pathology
- major coagulopathy
What scan do we do in suspected meningitis and when?
CT head before lumbar puncture if increased ICP suspected, to assess risk of brain herniation due to lumbar puncture
What investigations needs to be done in meningitis before starting Abx?
Two sets of blood cultures
What are some differential diagnoses for meningitis? (2)
- encephalitis - abnormal cerebral function (altered behaviour, speech, motor disorders especially with fever, seizures)
- drug-induced meningitis (Hx culprit drug use: NSAIDs, trimethoprim/sulfamethoxazole, amoxicillin, ranitidine - CSF shows neutrophilic pleocytosis)
What is the management flowchart for meningitis (no septicaemia)?
- meningitic signs predominate i.e. neck stiffness, photophobia
- dexamethasone 4-10mg/6h IV
- if signs of ICP –> ICU and do NOT do LP
- if no shock or ICP –> do LP
- 2g cefotaxime IV post-LP
- careful monitoring
What is the management flowchart for septicaemic meningitis?
- septicaemic signs predominate e.g. poor cap refill, cold hands and feet, rash
- do not attempt LP
- cefotaxime 2g IV
- signs of shock?
- Y = ICU for fluid resus, intubation, inotropes, vasopressors
- N = careful monitoring
In primary care, what should be done immediately when bacterial meningitis suspected?
IV/IM benzylpenicillin then send to hospital
In hospital, when should lumbar puncture be delayed in meningitis? (4)
- sepsis/rapidly evolving rash signs
- severe respiratory/cardiac compromise
- significant bleeding risk
- signs of ICP e.g. papilloedema, neurological signs, seizures, GCS<12
What do we do if raised ICP in meningitis? (5)
- secure airway + high-flow oxygen
- bloods and blood cultures from IV access
- IV dexamethasone
- IV Abx - cefotaxime (+/- ampicillin)
- CT
What do we do if normal ICP in meningitis? (4)
- take bloods and blood cultures
- do lumbar puncture
- IV Abx
- IV dexamethasone (AVOID in meningococcal septicaemia)
- (CT not normally done)
What are the immediate Abx given for meningitis? (3)
- first-line: 3rd generation cephalosporin - cefotaxime or ceftriaxone
- if >55 / immunocompromised: add ampicillin (or amoxicillin/rifampicin)
- (Abx given before LP if high ICP, after LP if normal)
- if in GP: IM/IV benzylpenicillin (ceftriaxone if allergic)
What do we give alongside Abx in meningitis?
IV dexamethasone - shortly before/after first dose of Abx, associated with reduced risk of complications
Avoid if meningococcal septicaemia
In meningitis, do you give Abx before or after lumbar puncture?
Empirical Abx before LP (cefotaxime/ceftriaxone), targeted Abx after
What targeted Abx can we give for meningitis? (3)
- Listeria monocytogenes - amoxicillin (+ gentamicin)
- S. aureus - flucloxacillin (vancomycin if penicillin allergic/MRSA)
- Mycobacterium tuberculosis - isoniazid/pyridoxine
- (rest are cefotaxime/ceftriaxone)
What Abx do we give for meningitis in children <3 months?
IV cefotaxime + amoxicillin (to cover for Listeria monocytogenes)
NICE advises against giving any corticosteroids if <3m
–> (Consider dexamethasone if frankly purulent CSF, CSF WCC>1000/mL, protein conc>1g/L, bacteria on Gram stain)
NOT ceftriaxone - contraindicated in <3m as it displaces bilirubin from albumin-binding sites = accumulates in tissues
How would we manage viral meningitis? (3)
- supportive measures
- usually self-limiting
- maybe antivirals
What do we give to close contacts of those with meningitis?
Prophylactic Abx - oral ciprofloxacin or rifampicin
What are some complications of meningitis? (9)
- deafness (sensorineural hearing loss - most common complication)
- septicaemia
- shock
- DIC
- cerebral oedema
- renal failure
- cranial nerve lesion
- seizures
- hydrocephalus
Describe the prognosis of (bacterial vs viral) meningitis.
- bacterial meningitis - fatal if untreated
- viral meningitis - resolves spontaneously in majority of cases
What is the initial empirical therapy for meningitis in patient aged <3 months?
IV cefotaxime + amoxicillin (or ampicillin)
What is the initial empirical therapy for meningitis in patient aged 3 months-50 years?
IV cefotaxime (or ceftriaxone)
What is the initial empirical therapy for meningitis in patient aged >50y?
IV cefotaxime (or ceftriaxone) + amoxicillin (or ampicillin)
What is the Abx therapy for meningococcal meningitis?
IV benzylpenicillin or cefotaxime (or ceftriaxone)
What is the Abx therapy for pneumococcal meningitis?
IV cefotaxime (or ceftriaxone)
What is the Abx therapy for meningitis caused by Haemophilus influenzae?
IV cefotaxime (or ceftriaxone)
What is the Abx therapy for meningitis caused by Listeria?
IV amoxicillin (or ampicillin) + gentamicin
What is the Abx therapy for meningitis if patient allergic to penicillin/cephalosporins?
Chloramphenicol
Do you do lumbar puncture or IV cefotaxime first in suspected meningococcal meningitis?
IV cefotaxime first
