CNS infections Flashcards
Untreated CNS infection may lead to?
- Brain herniation and death.
- Cord compression and necrosis with subsequent permanent paralysis.
Describe pyogenic meningitis.
Thick layer of suppurative exudate covering leptomeninges over brain surface. With exudate in basal and convexity surface.
Thick layer of suppurative exudate covering leptomeninges over brain surface. With exudate in basal and convexity surface.
Pyogenic meningitis.
Microscopic findings in pyogenic meningitis?
Neutrophils in subarachnoid space.
Treatment of community acquired meningococcal meningitis?
Ceftriazone IV 2g BD for 5 days.
If penicillin allergic: Chloramphenicol IV 25mg/kg QDS.
Treatment of community acquired pneumococcus meningitis?
10 days Ceftriaxone IV 2g BD (If penicillin allergic: Chloramphenicol IV 25mg/kg QDS)
+ 4 days Dexamethasone IV 10mg QDS.
Viral meningitis is common in which seasons?
Late summer/autumn.
Viral meningitis is typically due to which viruses?
Enteroviruses e.g. ECHO virus.
Diagnosis of viral meningitis is by?
- Viral stool culture.
- Throat swab.
- CSF PCR.
Treatment of viral meningitis?
Generally supportive as condition is self-limiting.
Symptoms of meningitis and septicaemia?
- Fever.
- Headache.
- Vomiting, diarrhoea.
- Muscle pain.
- Stomach cramps.
- Fever with cold hands and feet.
- Stiff neck, dislikes bright lights, convulsions/seizures.
- Drowsy/difficult to wake.
- Confused and irritable.
- Pale, blotchy skin, spots/rash.
Which pathogen is typically responsible for community acquired bacterial meningitis in neonates?
Listeria, Group B Strep, E. Coli.
Which pathogen is typically responsible for community acquired bacterial meningitis in children?
H. influenza.
Which pathogen is typically responsible for community acquired bacterial meningitis in ages 10-21?
Neisseria meningitidis.
Which pathogen is typically responsible for community acquired bacterial meningitis in those over 21 but younger than 65?
Strep. pneumoniae > Neisseria meningitidis.
Which pathogen is typically responsible for community acquired bacterial meningitis in those over 65?
Strep. pneumoniae > Listeria.
Risk factor for developing community acquired Listeria monocytogenes meningitis?
- Decreased cell mediated immunity.
Risk factor for developing community acquired Staph. or Gram negative bacilli meningitis?
Neurosurgery/head trauma.
Risk factor for developing community acquired Strep. pneumoniae meningitis?
Fracture of cribriform plate.
Basilar skull fracture predisposes to bacterial meningitis of which causative pathogen?
- Strep. pneumoniae.
- H. influenzae.
- Beta-haemolytic Strep group A.
Head trauma or post-neurosurgery predisposes to bacterial meningitis of which causative pathogen?
- Staph. aureus.
- Staph. epidermidis.
- Aerobic GNR (gram -ve bacilli).
CSF shunt predisposes to bacterial meningitis of which causative pathogen?
- Staph. epidermidis.
- Staph. aureus.
- Aerobic gram -ve bacilli.
- Propionibacterium acnes.
Immunocompromised state predisposes to bacterial meningitis of which causative pathogen?
- Strep. pneumoniae.
- N. meningitidis.
- Listeria.
- Aerobic gram -ve bacilli inc. pseudomonas aeruginosa.
A complication of bacterial meningitis includes purulence, resulting in?
- Clusters at base of brain.
- Convexities of rolandic and sylvian sulci.
- Exudate around nerves (CN III, VI are esp. vulnerable).
What prevents meningitis from becoming an abscess?
Pia mater.
Abscesses may cause secondary ventriculitis and thus?
Meningitis.
A complication of bacterial meningitis includes?
- Purulence.
- Invasion.
- Cerebral oedema (temporal vs cerebellar).
- Ventriculitis/hydrocephalus.
Symptoms of meningococcal meningitis are due to what?
Endotoxin.
Meningococcal meningitis most often occurs in who?
Young children.
N. meningitidis is carried where?
In the throat of healthy carriers.
Where might N. meningitidis be found in CSF?
In leukocytes.
What does H. influenzae require for growth?
Blood factors.
Most common meningitis causing type of H. influenzae in those under 4 years old?
H. influenzae type b.
S. pneumoniae is commonly found where?
Nasopharynx
Who is most susceptible to S. pneumoniae meningitis?
- Hospitalised.
- CSF skull fractures.
- Diabetics/alcoholics.
- Young children.
Describe Listeria monocytogenes histologically.
Gram positive bacilli causing mainly bacteraemic illness.
Who is most commonly affected by Listeria monocytogenes?
- Neonates.
- > 55 y/o.
- Immunosuppressed esp. malignancy.
Antibiotic of choice against Listeria monocytogenes?
- IV ampicillin/amoxicillin.
Listeria monocytogenes is intrinsically resistant to which antibiotic?
Ceftriaxone.
Tuberculous meningitis is common in who due to what?
Elderly due to disease reactivation.
How does Tuberculous meningitis present?
Often as non-specific ill health.
Management of Tuberculous meningitis?
- Rifampicin.
- Isoniazide.
and then add: - Pyrazinamide.
- Ethambutol.
Cryptococcal meningitis is due to which type of organism?
Fungus.
Cryptococcal meningitis is associated with which disease?
HIV.
Test for Cryptococcal meningitis?
Serum and CSF cryptococcal antigen.
Management of Cryptococcal meningitis?
- IV Amphotericin B/ Flucytosine.
- Fluconazole.
Treatment algorithm for someone with suspected meningitis with no allergies, under 60 years old?
- Cefotaxime 2g QDS OR Ceftriaxone 2g BD IV.
+ Dexamethasone 10mg QDS IV.
Treatment algorithm for someone with suspected meningitis with no allergies, over 60 years old?
- Cefotaxime 2g QDS OR Ceftriaxone 2g BD IV.
+ Dexamethasone 10mg QDS IV.
+ Amoxicclin 2g IV every 4 hours.
What would be added to the treatment algorithm for someone with suspected meningitis and no allergies, where there is suspicion of penicillin resistant pneumococci?
+ Vancomycin 15-20mg/kg BD.
OR
+ Rifampicin 600mg BD.
Treatment algorithm for someone with suspected meningitis with a penicillin or cephalosporin allergy, under 60 years old?
- Chloramphenicol 25 mg/kg QDS IV.
- Dexamethasone 10mg QDS IV.
Treatment algorithm for someone with suspected meningitis with a penicillin or cephalosporin allergy, over 60 years old?
- Chloramphenicol 25 mg/kg QDS IV.
- Dexamethasone 10mg QDS IV.
- Co-trimoxazole 10-20mg/kg (of trimethroprim component) in four divided doses.
Clinical signs of bacterial meningitis?
- Fever.
- Stiff neck.
- Alteration in consciousness.
Symptoms of bacterial meningitis?
- Headache.
- Vomiting.
- Pyrexia.
- Stiff neck.
- Photophobia.
- Lethargy.
- Confusion.
- Rash.
How many tubes of CSF in lumbar puncture?
4
What should be asked for in CSF interpretation?
- Haematology: cell count, differential. TWICE.
- Microbiology: gram stain and culture.
- Chemistry: glucose and protein.
CSF is 99% predictive of bacterial meningitis if?
- WBCC >2000.
- Neutrophils >1180.
- Protein > 220 mg/dl.
- Glucose <34 mg/dl.
- Glucose (CSF/serum) <0.23.
What infections, other than bacterial meningitis cause neutrophilic pleocytosis and low CSF glucose?
- Viral meningitis (early stage).
- Parameningeal foci/cerebritis.
- Leakage of brain abscess into ventricle.
- Amoebic meningoencephalitis.
- TB meningitis (rare, usually early stage only).
What are the non-infectious causes of neutrophilic pleocytosis and low CSF glucose?
- Chemical meningitis e.g. due to contrast.
- Behcet syndrome.
- Drug-induced (NSAIDs).
What is aseptic meningitis?
Non-pyogenic bacterial meningitis.
What spinal fluid composition is typically seen in aseptic meningitis?
- Low WBCC.
- Minimally elevated protein.
- Normal glucose.
Name an infectious cause of aseptic meningitis?
- HSV 1 and 2.
- Syphilis.
- Listeria.
- TB.
- Cryptococcus.
- Leptopspirosis.
- Cerebral malaria.
- African tick typhus.
- Lyme disease.
Name a non-infectious cause of aseptic meningitis?
- Carcinoma.
- Sarcoidosis.
- Vasculitis.
- Dural venous sinus thrombosis.
- Migraine.
- drugs: Co-trimoxazole, NSAIDs.
Indications for hospital admission in acute adult bacterial meningitis?
- Signs of meningeal irritation.
- Impaired conscious level.
- Petechial rash.
- Febrile/unwell with recent fit.
- Any illness esp. headache with meningococcal infection even if received prophylactic antibiotic.
Immediate management following hospital admission in acute adult bacterial meningitis?
- Blood: culture and coagulation screen.
- Initial antibiotic therapy until pathogens identified.
- Throat swab to be plated ASAP.
- Disrupt and swab/aspirate any petechial or purpuric skin lesions for microscopy and culture.
Who needs CT before lumbar puncture?
- Immunocompromised.
- History of CNS disease.
- New onset seizure.
- Papilloedema.
- Abnormal conscious level.
- Focal neurological deficit.
All adults with suspected meningits should undergo lumbar puncture except when?
- Clear contraindication exists or there is confident clinical diagnosis of meningococcal infection with typical meningococcal rash.
What should be given before lumbar puncture in adults with suspected acute bacterial meningitis?
Antibiotics.
What causes meningococcal meningitis?
N. meningitidis.
What should be given to all patients suspected of bacterial meningitis?
Steroids.
Antibiotics - Ceftriaxone or Chloramphenicol + Vancomycin if penicillin allergic.
How should steroids be administered to patients suspected of bacterial meningitis?
10mg IV 15-20 minutes before or with the first dose of antibiotics. Then every 6 hours for 4 days.
When should steroids not be given in suspected bacterial meningitis?
- Post surgery.
- Severe immunocompromise.
- Meningococcal or septic shock.
- If hypersensitive to steroids.
What features on admission may suggest meningococcal meningitis in adults?
- Haemorrhagic diathesis.
- Deteriorating consciousness.
- Multi-organ failure.
- Rapidly developing rash.
- Age >60.
What is haemorrhagic diathesis?
- Tendency to bleed (spontaneously, excessively, delayed onset etc).
How does meningitis (of all types) in adults typically present on admission?
- Tachycardia.
- GCS <12 on admission.
- Low GCS.
- Cranial nerve palsy.
- Seizures within 24 hours.
- Hypotension.
- Age >60.
Initial management of bacterial meningitis with low GCS (<12) of fluctuating conscious level (fall in GCS of >2)?
- High supervision area.
- Baseline investigations.
- Secure airway.
- High flow O2.
- IV 2g Ceftriaxone stat (+/- amoxicillin if >55 to cover listeria).
- IV corticosteroids.
- Don’t wait for CT scan/LP.
Prevention of secondary meningitis?
- Report to public health/Health protection all suspected cases ASAP to ensure appropriate measures used.
- GPs must be aware of prevention policies to locate close contacts + implement chemoprophylaxis and vaccination.
- GP records of close contacts of meningococcal disease should be labelled as increased risk for 6 months.
Rifampicin contact prophylaxis regime of bacterial meningitis?
Rifampicin:
- > 12 years: 600mg PO 12-hourly for 4 doses.
- 3-11 months: 10mg/kg PO/IV 12-hourly for 4 doses.
What warnings must be given to those on Rifampicin contact prophylaxis regime of bacterial meningitis?
- Reduced efficacy of oral contraceptives.
- Red urine.
- Staining of contact lenses.
Ciprofloxacin contact prophylaxis regime of bacterial meningitis?
- 500mg PO single dose if >12 years. Avoid in younger children.
NB this is not yet licensed but has been used extensively in school + community outbreaks.
Ceftriaxone contact prophylaxis regime of bacterial meningitis?
- Adults: 250mg IM single dose.
- <12 years: 125mg IV single dose.
What vaccines may be given to prevent bacterial meningitis?
- Neisseria meningitidis.
- HiB.
- Strep. pneumoniae.
Meningococcal bacteria colonises what?
Nasopharynx of humans.
