Table of Contents
- bacterial meningitis and meningococcal sepsis are two separate but overlapping entities which often co-exist
- most cases of bacterial meningitis result from seeding from an episode of bacteraemia with a virulent organism (although in neonates, this may just be from an organism causing a UTI)
- some cases of bacterial meningitis result from extension of regional infection, such as from V-P shunts, etc.
ED Mx of suspected meningitis
- high priority triage (eg. triage 2)
- A,B,C's as usual
- iv access
- check BSL
- bloods for FBE, U&E, blood cultures x2 sets, clotting profile, meningococcal PCR
- careful iv fluid resuscitation if hypotense as high risk of delayed APO - see sepsis / septicaemia
- stratify risk (see below) to decide who gets immediate antibiotic Rx, and who gets CT/LP
- if primarily septicaemic, immediate iv antibiotics DO NOT do LP
- if primarily meningitis, consider LP before iv antibiotics if not contraindicated (see below) and doesn't delay antibiotics by more than 20-30min.
- iv dexamethasone 0.15mg/kg to max 10mg qid for 4 days start before or at 1st dose antibiotics, particularly for pneumonococcal cases. Cease if non-bacterial cause identified.
- reduces mortality, severe hearing loss and long-term neurological sequelae in bacterial cases, esp. if pneumococcal.
- iv ceftriaxone 50mg/kg to max 2g bd
- consider iv benzyl penicillin 60mg/kg to max 2.4g 4hrly or ampicillin 2g qid if immunosuppressed or possible Listeria (eg. age < 3 months or age > 55 years)
- consider adding vancomycin 12.5 mg/kg up to 500 mg IV 6-hrly if Strep. pneumoniae or Staph. aureus are suspected, or neutrophils are in CSF but no organisms seen (and if viral meningitis / meningococcal disease are unlikely).
- infectious disease isolation measures
- nurse patient at 30deg head up if altered mental state
- if meningococcal disease, it is a notifiable disease and will need contact tracing and chemoprophylaxis for contacts.
high risk features that mandate immediate iv antibiotic Rx
- presence of meningococcal rash
- fever, headache, photophobia and objective neck stiffness (not just soreness)
- fever with seizures (excluding typical febrile convulsions in young children)
- fever with altered mental state (excluding post-ictal following a typical febrile convulsion or other obvious cause for the mental state change)
- sick looking febrile neonate or infant
- rectal temp > 38deg C in a neonate (aged < 1 month or weighing < 3.5kg)1)
- NB. at risk patients with known spinal abnormalities such as spina bifida or V-P shunts should have early neurosurgical consults
moderate risk features that suggest an LP may be warranted
- febrile neonate or infant
- fever, headache, with photophobia &/or neck soreness with no other focus of infection evident
- fever, headache and already on antibiotics
- see also interpretation of CSF findings
- most patients require the diagnosis to be confirmed by lumbar puncture (LP) as confirmation will not only aid diagnosis but assist in determining duration and type of ongoing antibiotic Rx.
- patients with atypical presentations in whom tuberculosis (TB) is possible, should be considered for 10ml CSF sent for TB cultures in addition to usual CSF studies.
- unless the risk of an intracranial mass lesion (eg. abscess, subdural empyema) is very low (eg. previously well young adult or child with illness < 24hrs), a CT brain is usually recommended prior to performing a lumbar puncture (LP).
contraindications to LP
- widespread rash
- evidence of coagulopathy
- drowsiness / impaired consciousness
- signs of raised ICP (bradycardia, hypertension, papilloedema, periodic breathing)
- focal neurology
- mass lesion on CT scan
- possible hydrocephalus on CT scan
- if LP is contraindicated due to possible raised intracranial pressure, neurosurgical consultation may be indicated to consider a diagnostic ventricular tap.
the diagnostic dilemma
- meningitis is one of the main dilemmas for the ED physician
- missing or delaying Rx for a case may have fatal consequences
- the gold standard for diagnosis involves CT brain and lumbar puncture (LP) - both of which are resource-intense, costly and expose the patient to significant risks
- for every 1 case of meningitis, there may be 1,000 cases of fever and headache - you can't be doing an LP on them all!
- 95% of adult patients with meningitis have at least 2 of fever, headache, neck stiffness and altered mental state - but this does not help us because nearly all influenza patients will have fever and headache.
- altered mental state is generally a late symptom and is present in about half the patients at presentation, but this means absence of altered mental state is not in itself reassuring.
- neck stiffness is NOT a reliable sign in young children or the immunocompromised
- a blood test does not allow the exclusion or the diagnosis of meningitis (excluding PCR but these are not immediately available to alter ED Mx)
- patients who are already on antibiotics can become a diagnostic nightmare for the ED physician as clinical signs and even CSF findings become less reliable to exclude meningitis.
- prior antibiotics usually prevent the culture of bacteria from the CSF.
- antibiotics are unlikely to significantly affect the CSF cell count or biochemistry in samples taken <24 hours after antibiotics.
- thus one needs to stratify risk to decide who gets immediate antibiotic Rx, and who gets CT/LP, and who can be observed, and who can be safely discharged.
- furthermore, an LP cannot fully exclude bacterial meningitis on micro findings alone, and thus if one has a high clinical suspicion of bacterial meningitis, the safe option is to treat with appropriate iv antibiotics +/- aciclovir EARLY and continue them irrespective of CSF micro results.
- no fever or meningism signs but just lethargy, obtundation
- may have subtle signs
neonates and young infants
- poor feeding, irritability, vomiting
- “a sick looking child with a fever has meningitis until proven otherwise”
normal cell counts on CSF
- this makes diagnosis tough!
- this is more likely to be the case with patients already on oral antibiotics
meningitis.txt · Last modified: 2012/01/16 06:55 by 127.0.0.1