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