Meningitis Flashcards
Define meningitis
Inflammation of the meninges. Usually caused by infection;
viral or bacterial
What is the epidemiology of meningitis?
- Mainly affects infants, children and elderly
- It is a notifiable disease to Public Health England
What pathogens cause meningitis in neonates (0-3 months)
- Group B streptococcus*
- E.coli
- Listeria Monocytogenes
- S. pneumoniae
What pathogens cause meningitis in children (3m- 6 yrs)
- Neisseria meningitidis
- Strep Pneumoniae
- Haemophilus influenzae (less common due to vaccination)
What pathogens cause meningitis in adults (6-60yrs)
- N.meningitidis
- Strep Pneumoniae
What pathogens cause meningitis in the elderly? (60+yrs)
- Listeria monocytogenes
- N.meningitidis
- Strep Pneumoniae
What pathogen causes meningitis at all ages?
Staph aureus
What pathogen causes meningitis in pregnant women?
Listeria monocytogenes
What pathogens cause meningitis in immunocompromised people?
Viral
- Cytomegalovirus
-Cryptococcus neoforman
- HIV
- HSV
Mycobacterium TB
What are risk factors of meningitis?
- Intrathecal drug administration
- Immunocompromisation
- Elderly
- Pregnant
- Bacterial endocarditis
- Crowding
- Diabetes
- Malignancy
- IV drug use
- Non-vaccination
Describe the pathophysiology of meningitis
- Microorganisms reach the meninges either by direct contagious spread, ENT infections or through the bloodstream, host response causes most damage
- Inflammatory cytokines
released which result in cerebral oedema and ischaemia causing increased ICP eventually
leading to death.
Describe acute bacterial meningitis
- Sudden onset
- N.meningitidis can cause meningococcal septicaemia causing non-blanching rash (sign of DIV)
- Pus formation around the meninges causes cranial nerve palsies and hydrocephalus
Describe chronic of meningitis
- TB in immunocompromised, more insidious onset
- Always consider in patients who are immunocompromised, aseptic meningitis, from a
high prevalence area - Brain is covered with grey-green exudate
Describe viral meningitis
- Predominantly lymphocytic reaction with no pus formation
- So usually less severe as it causes no/little cerebral oedema
Describe features of n.meningitidis
- Gram negative diplococcus
- Vaccines available (Men B + C, MenACWY vaccine)
- 10% mortality
- Non blanching purpuric rash (meningococcal septicaemia –> DIC –> very easy bleeds)
Describe features of s.pneumoniae
- Gram positive diplococcus in chains
- PCV vaccine
- 25% mortality
Describe features of group B strep
- Gram positive coccus in chains
- Most common cause of neonatal meningitis
- Because it colonises maternal vagina
Describe features of listeria monocytogenes
- Gram positive bacillus
- Affects extremes of age and pregnant women
- Found in cheese
What are the symptoms of meningitis?
Triad: Headache, neck stiffness, fever
What are symptoms of acute bacterial infection meningitis?
- Sudden onset
- Papilloedema - usually bilateral
- Systemic symptoms - Intense malaise, rigours, photophobia, vomiting
- Reduced GCS, focal CNS signs, seizures
What are symptoms of viral meningitis?
- Self limiting lasting 4-10 days
- May have headache for months afterwards
What are the symptoms of chronic meningitis?
- Due to TB
- Long history of vague symptoms of headache, anorexia, vomiting
- Triad is absent or late sign
What do neonates and children present with?
non-specific symptoms e.g
- hypotonia
- poor feeding
- lethargy
- hypothermia
- bulging fontanelle
So have low threshold for LP (lumbar puncture)
What are the thresholds in neonates and children for a lumbar puncture in meningitis?
- Under 1 months presenting with fever
- 1 – 3 months with fever and are unwell
- Under 1 years with unexplained fever and other features of serious illness
What are signs of meningitis?
- Signs - Kernig’s (pain when straightening knee whilst hip is flexed at 90 degrees)
and - Brudzinski’s (bottom - involuntary knee/hip flexion when flexing the neck)
How do you diagnose meningitis?
- Blood cultures
- Throat swabs – viral and bacterial
- Lumbar puncture: Do not wait for results to give empirical antibiotics
What is normal CSF appearance?
Clear
What is the normal CSF opening pressure?
90-180 mmHg
What is the normal amount of WBC in CSF?
<8 cell/uL
What is the normal amount of proteins in CSF?
15-45 mg/dl
What is the normal amount of glucose in the CSF?
50-80 mg/dL
What is the appearance of CSF in bacterial meningitis?
Cloudy yellow
What is the opening pressure like of CSF in bacterial meningitis?
Elevated
What is the WBC count like of CSF in bacterial meningitis?
Increased, neutrophilia (>1000-2000)
What is the protein count like of CSF in bacterial meningitis?
Elevated (>200 mg/dl)
What is the glucose count like of CSF in bacterial meningitis?
Low (<40 mg/dL)
What is the appearance of CSF in viral meningitis?
Clear
What is the opening pressure of CSF like in viral meningitis?
Normal
What is the WBC count of CSF like in viral meningitis?
Elevated, lymphocytic predominance (<300 cell/uL)
What is the protein count of CSF like in viral meningitis?
Elevated (<200 mg/dl)
What is the glucose count of CSF like in viral meningitis?
Normal
What is the appearance of CSF like in fungal/TB meningitis?
Clear + fibrinous
What is the opening pressure of CSF like in fungal/ TB meningitis?
Normal-elevated
What is the WBC count of CSF like in fungal/ TB meningitis?
Elevated (<500 cell/uL, lymphocytosis)
What is the protein count of CSF like in fungal/ TB meningitis?
Elevated (>200mg/dl)
What is the glucose count of CSF like in fungal/ TB meningitis?
Normal-low
What is lumbar puncture contraindicated in?
Increased ICP (due to tentorial herniation risk)
What is the GP treatment of
bacterial meningitis?
Immediate IM or IV Benzylpenicillin
+
Withhold treatment if true penicillin anaphylaxis, immediate referral to hospital
What is the hospital treatment of bacterial meningitis?
- IV Cefotaxime or IV Ceftriaxone
- Add IV Vancomycin in recent travellers
- Add amoxicillin in neonates and elderly (covers listeria)
+ - Steroids simultaneously (oral dexamethasone)
Why are steroids given simultaneously in meningitis?
- to reduce cerebral oedema and complications (hearing loss,
neurological damage) - 4 times daily for 4 days to children over 3 months
What is the prophylaxis for bacterial meningitis?
- Contact in the last 7 days
- Single dose of Oral Ciprofloxacin or Rifampicin (except in
pregnancy)
What is the treatment for viral meningitis?
- LP can be done, usually self limiting (nothing if enteroviruses)
- Acyclovir may be used in HSV or VZV meningitis
What are complications of meningitis?
- Hearing loss
- Seizures/epilepsy
- Cognitive impairment/disability
- Memory loss
- Focal neurological deficit
- DIC (meningococcal septicaemia)
- Waterhouse Friedrichsen syndrome
What is Waterhouse Friedrichsen syndrome?
Adrenal insufficiency caused by intra-adrenal haemorrhage as a result of meningococcal DIC
