Meningitis
Epidemiology
Patho-genesis
20-100/100,000 neonates; 5/100,000 1/12 – 4yrs; 90% occur <5yrs; 90% mortality untreated (10% treated if meningococcus or Hib; 30% treated if
pneumococcus); 30% survivors have long term sequelae
In paeds: 4.5% mortality; 10-20% intellectual / auditory complications; asymptomatic N meningitidis nasal carriage in 10%; meningococcal sepsis
bimodal (0-4yrs, 15-25yrs); <3/12 + febrile = 1% incidence
Encephalitis: mortality HSV 60% without trt, 30% with trt
Usually haematogenous spread, sometimes direct; damage from inflamm response
Strep pneumoniae (60%): G+ive diplococci; more indolent course; FND prominent; 50% also have pneumonia; 25% resistant to penicillin,
9% resistant to cefotaxime; if resistance, use vanc + rifampicin
N meningitidis (16%): G-ive aerobic diplococci; use benpen 45mg/kg Q4h IV for 3-5/7, or cefotaxime/ceftriaxone if allergy; 13 serogroups; C>B in
Aussie (usually other way round in developed countries); reservoir in NP; aerosol transmission; sudden onset headache, fever, true rigors, neck
stiffness, N+V, photophobia, altered LOC, AP, limb pain, arthritis, rash (in 40%, may take 6-12hrs to develop; haemorrhagic, petechial, purpuric; may
blanch initially); may be fatal in 12hrs (mortality 1-5% - up to 40% if invasive meningococcal disease); assoc with Waterhouse Friedrichsen syndrome
(acute adrenal haemorrhage)
Grp B strep (14%), E coli: if <3/12; Grp B strep use benpen 60mg/kg Q4h IV for 14-21/7
Hib (7%): if non-vaccinated; use cefotaxime / ceftriaxone
Listeria (2%): if neonate and immunocomp; use benpen or ampicillin
Staph: if CNS shunt, open wound, neurosurg
Viral: mumps, coxsackie, enterovirus, herpes, EBV, echovirus, HIV, CMV
Other bacterial: M TB, mycoplasma, borrelia, treponema pallidum, brucella
Fungi and parasites: cryptococcus neoformans (use amphotericin + flucytosine), toxoplasma gondii, cysticercosis
Drugs: NSAIDS, bactrim
Other: sarcoid, SLE, Wegener’s
Assessment
Investigation
Encephalitis: HSV (temporal + frontal  psych, memory, aphasia), HZV, EBV, CMV, enterovirus, adenovirus, rabies, vector-borne; post-viral (eg.
Influenza, measles, rubella, varicella, HIV); bacterial (rickettsia, leptospirosis, amoebic)
Brain abscess: haematogenous (30%; multiple, polymicrobial, often anaerobes/strep), local (30%; eg ear  bacteroides  temporal or cerebellar;
eg. Sinus and dental  anaerobes, strep  frontal), unknown (20%), neurosurg (10%; staph and G-ive rods); trt with cefotaxime and metronidazole
Hx: 25% bacterial present within 24hrs, viral present day 1-7 (5% within 24hrs); classic Sx absent in infants and elderly; fever in 80% bacterial (3040% viral); seizures in 30-40% children, 20-30% adults; confusion in 85% bacterial (25-50% viral); photophobia in 80% bacterial (60-70% viral);
headache + fever + neck stiffness present in 50% (2 present in nearly 100%)
OE: isolated CN lesion in 10-20%; look for shock; Kernig’s (passive knee extension in supine patient causes neck pain and hamstring resistance);
Brudsinski’s (passive neck flexion or single hip flexion causes involuntary flexion of both hips)
In children: 15% of neonates have physical findings (lethargy, seizures, poor feeding, fever, hypothermia, paradoxical crying, hypotonicity, bulging
fontanelle late); meningisim not present until 18/12; focal signs in 15% all cases, 30% pneumococcal; seizures in 30% (with worse than expected
mental status after); 15-20% decr LOC (more in pneumococcus); subdural effusion / empyema (30% in Hib, 20% in strep); may deteriorate after
Abx (bacteriolysis  inflamm); beware partially treated meningitis (more frequent V, longer duration of Sx); suspect encephalitis if seizures /
altered LOC / behaviour
Encephalitis: usually no motor/sensory Sx; psych, cognitive, seizure, mvmt disorder, LOC, confusion
Bloods: FBC, coag, blood cultures, U+E, BSL; Ag testing if blood/urine not helpful; ?procalcitonin
CT head: if papilloedema, altered LOC, FND, seizure, immunocomp, Ca, concern Re: SOL, history of CNS disease, seizure in week prior, >60yrs; CT
may be normal despite incr ICP in 45%; CT features of incr ICP = changes ventricle size, decr basilar cistern size, narrowed sulci, transfalcine
herniation, change in rate of grey/white matter
CT head encephalitis: diffuse hypoattenuation in temporal lobe, sparing of lentiform nucleus; mass effect in 80%; maybe vesicular haemorrhage
EEG in encephalitis: slowing of background rhythm or epileptiform; abnormal in 80% HSV
CXR
LP: do cell count, diff, glu, protein, Gram stain, culture, Ag (high sens and spec, esp Hib and neisseria), PCR; India ink if indicated (cryptococcal); use
non-styleted needle in small infants
Technique: SC ends at L1-2 (96%), T12 (2%), L3 (2%); lower in children; go L3-4; use USS if can’t feel IV spaces; avoid alcohol based skin preps; 2225G adult (12cm), 22-25G child (6cm), 2cm neonate; 20-30deg cephalad; replace stylet before removing; no evidence for immobilisation
after; normal OP = 7-18cm in adults, up to 20cm in 8-18yrs, 1-10cm in young child (incr p in meningitis, Ca, abscess, ICH, benign intracranial
HTN; decr in CSF leak, dehydration, hyperventilation)
Cell counts: mycoplasma, listeria, spirochetes, syphilis, leptospira, borrelia have less marked CSF changes; partially trted picture seen if close to
SA space (eg. Asbcess); LP within normal limits on cells in 2-3%; WCC >100 in 99% bacterial meningitis, >1000 in 90%; lymph >50% in 10%
bacterial; nearly 100% mononuclear in viral (may be more polymorphs in 1st 48hrs); turbid if >400 RBC, >200 WBC; lymphocytes may
predominate in listeria and neonates
Protein incr 0.01g per 1000 RBC (also incr by alcoholism, abscess, Ca, haem, trauma, DM, epilepsy, disc herniation, MS, polio, incr Ur);
Glu decr in mumps and sometimes in HZV/HSV;
Ag tests: latex agglutination (rapid, high sens, 50-90% sens for neisseria, 50-100% for pneumococcus, 80% for Hib, 90% for cryptococcus, Grp B
strep)
PCR (for HSV, >95% sens, 100% spec; for TB, 80% sens, >95% spec)
Xanthochromia: cause by blood >4hrs, extreme incr protein, incr carotin, severe jaundice
Traumatic tap: in 15%; RBC usually >400-1000; clearing
SE: uncal/tentorial herniation (can occur up to 1hr post), post-LP headache (2-15%; 70% with 16-19G, 20-40% with 20-22G, 5-10% with 24-27G;
keep bevel parallel to fibres to decr incidence by 50%; incr risk if young, thin, slim female; onset 24-48hr post-procedure, duration 4-8/7,
worse on standing, suboccipital; best rest, fluid, analgesia, caffeine, blood patch), epidural haematoma (lac of ant/lat epidural
venous plexus), epidermoid cyst, infection, paraparesis, nerve root inj
CI: local sepsis, anticoag, bleeding diathesis, plt <50, incr ICP, SOL
Opening p
N neonate N child
5
1-10
WCC
<30
N adult
7-18
Bacterial
>30
<4
<2
0
0
>80%
PMN (neut)
<5
0
0
Up to 10,000
<5
<4
<20
Protein
<0.8
<0.4
Glu
Glu % serum
RBC
>2.5
50%
<2
>2.5 2.5-3.5
>40% 60-80%
<2
Gram Stain
Culture
Viral
<30
Encephalitis
Slightly high
TB
Fungal
30
Ca
20
<500
Up to 500
Up to 500
Up to 500
Up to 10,000 Up to 5000 Up to 1000
<5-10
%PMN
MMN (lymph)
Prtl trted
<100 (10%)
>1-2
<2.2
0.18-0.45
0
<50%
>10-100
<100
N / Up
0.4 - 2
N / Low
+ in 20-50%
+ in 30-70%
- ive
- ive
<50%
>50%
>50%
High early
>100 >100 >100
Normal/high
<40%
Normal/high
If traumatic, subtract 1 WBC per 1000 RBC
+ in 60-80%
+
<100
<50%
High late
0.4 - 2
N
>2
Low late
<30%
- ive
+ late
>2
<2.2
>2
<2.2
<40%
<40%
.
-ive
–ive
-ive
-ive
Bacterial Ag
+ in 80%
+ in 70%
- ive
- ive
–ive
-ive
A+B
C: if shocked give IVF; SIADH in 30% children so use 50% maintenance after resus
Supportive: seizure control, analgesia, fever control, BSL
Steroids: IV dex 10mg (0.2mg/kg) Q6h for 4/7 if >1/12; give at least 15-30mins before Abx; give within 30mins; decr host response to
Mng
bacteria; decr deafness; in children halves incidence of audio / neuro sequelae (but >70% had Hib infections); in adults decr risk of
adverse outcome and mortality; benefit best in pneumococcal (adult) and Hib (children)
Antibiotics: give within 30mins (give before LP if there will be >20min delay
to LP); once sens available, see above
<3/12:
amoxicillin 50mg/kg QID (TDS if <1/52)
+ cefotaxime 50mg/kg QID (BD if <1/52)
(give 100mg/kg loading dose if >1/12)
+ vancomycin 15mg/kg QID
(if suspect pneumococcus, G+ive diplococci seen, Ag +ive)
>3/12:
cefotaxime 100mg/kg loading dose  50mg/kg QID (max 2g)
or ceftriaxone IM 100mg/kg loading dose  80-100mg/kg OD (max 4g) (if no IV access)
+ amoxicillin 50mg/kg QID IV (max 2g)
(if suspect Listeria)
+ vancomycin 12.5mg/kg QID IV (max 500mg) (if suspect pneumococcus, G+ive diplococci seen, Ag +ive)
In adults: MCQ says ceftriaxone 2g + benpen 1.8g
Contact prophylaxis: meningococcus / Hib – give rifampicin 10mg/kg BD x4 (CI’ed in pregnancy and liver disease; ceftriaxone IM or
Complications
ciprofloxacin PO if CI’ed); contact = family and household contacts, those exposed to oral secretions, sexual partners
Encephalitis: aciclovir 10mg/kg TDS IV for HSV; ganciclovir for CMV
Seizures (30%), SIADH (30%), cerebral herniation, infarction, oedema, venous/sinus thrombosis, hydrocephalus, shock (10%), DIC, empyema (30%
Hib, 20% pneumococcal)
Notes from: Dunn, Cameron (adult and child), TinTin, Starship Guidelines
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