meningitis Flashcards
definition of meningitis
Inflammation of the leptomeningeal (pia mater and arachnoid) coverings of the brain, most commonly caused by infection.
aseptic meningitis
Characterized by clinical and laboratory evidence for meningeal inflammation and negative routine bacterial cultures.
May be secondary to:
- Enterovirus (most common cause), mycobacteria, fungi, spirochetes.
- Autoimmune e.g. Sarcoidosis, Behcet’s disease, Systemic lupus erythematosus.
- Malignancy (lymphoma, leukaemia, metatstatic carcinomas).
- Medication (NSAIDs, trimethoprim, azathioprine).
mollaret’s meningitis
recurrent benign lymphocytic meningitis
50% exhibit transient neurological manifestations
most common cause is HSV-2
CSF: large granular plasma cells on Papanicolaou’s stain, PCR for HSV DNA.
treat with acyclovir
aetiology opf bacterial meningitis
Neonates: Group B streptococci, Escherichia coli, Listeria monocytogenes.
Children: Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae.
Adults: Neisseria meningitidis (meningococcus), Streptococcus pneumoniae, tuberculosis.
Elderly: Streptococcus pneumoniae, Listeria monocytogenes.
TB
aetiology of viral meningitis
enteroviruses
mumps
HSV
VZV
HIV
CMV
aetiology of fungal meningitis
cryptococcus - associated with HIV
RF for meningitis
- close communities - dorms
- basal skull fractures
- mastoidosis
- sinusitis
- inner ear infections
- alcoholism
- immunodeficiency - transplant/malignancy
- splenectomy
- sickle cell anaemia
- CSF shunts
- intracranial surgery
epidemiology of meningitis
Variation according to geography, age, social conditions.
UK Public Health Laboratory Service receives 2500 notifications/year.
More common in recent visitors to the Haj (meningococcal serogroup W135), epidemics occur in the meningitis belt of Africa(meningococcal serogroup A).
sx of meningitis
severe headache
photophobia and neck stiffness and kernig’s sign= meningism
neck or backache
irritability
drowsiness
vomiting
high-pitched crying or fits - common in children
clouding of consciousness
fever
leg pain
cold hands and feet
abnormal skin colour
travel and exposure for meningitis
exposure to rodents (Lymphocytic choriomeningitis virus),
ticks (e.g. Lyme borrelia, Rocky Mountain spotted fever),
mosquitoes (West Nile virus, St. Louis encephalitis virus),
sexual activity (HSV-2, HIV, syphilis),
travel (C. immitis, A. cantonensis) and contact with other individuals with viral exanthems (enteroviruses).
signs of meningitis
signs of meningism
signs of infection
reduced GCS, coma
seizures +- focal neurological signs +- opisthotonus
shock - prolonged capr refill, DIC, hypotension
zoster - cold sore/genital vesicles
HIV - lymphadenopathy, dermatitis, candidiasis, uveitis
leptospirosis - bleeding +- red eye
mumps - parotid swelling
glandular fever - sore throat +- jaundice, +- nodes
splenectomy scar = immunodeficient
signs of meningism
photophobia
neck stiffness
Kernig’s sign - hips flexed, pain/resistance on passive knee extension
Brudzinski’s sign - flexion of hips on neck flexion
signs of infection - meningitis
fever
tachycardia
hypotension
skin rash - non-blanching petechiae with meningococcal septicaemia, may ony be 1 or 2 spots
altered mental state
Ix for meningitis
blood
throat swab - 1 bacteria and 1 virology
imaging
LP
staining of petechiae scrapings may detect meningococcus in 70%
Additional studies e.g. viral PCR, staining/culture for mycobacteria and fungi, HIV test depending on the clinical presentation/CSF findings
blood for meningitis
2 sets of cultures - dont delay AB
UE
FBC - low WCC = immunocomp - get help
LFT
glucose
coagulation
imaging for meningitis
CT scan to exclude mass lesion or raised ICP before LP
must be before LP if immunodeficiency, history of CNS disease, low consciouness, fit, focal neurological deficit, or papilloedema
LP for meningitis
note opening CSF pressure
CSF to microscopy with culture sensitivity and gram staining: (Streptococcus pneumoniae: Gram-positive diplococcic, Neisseria Meningitidis: gram-negative diplococcic), biochem and cytology
LP for bacterial meningitis
Cloudy CSF,
high neutrophils and protein,
low glucose (CSF: serum glucose ratio of<0.5).
LP for TB meningitis
fibrinous CSF,
high lymphocytes protein,
low glucose
LP for viral meningitis
high lymphocytes and protein,
normal glucose
ddx for meningitis
malaria
encephalitis
septicaemia
subarachnoid
dengue
tetanus
Mx for meningitis
immediate IV/IM AB if suspected
- before LP or CT
- blood cultures 1st
- third-generation cephalosporin (cefotaxime 2 g qds or ceftriaxone 2 g bd).Benzylpenicillin may be given as initial blind therapy and for sensitive meningococci and pneumococi.
- amoxicillin and gentamicin for listeria
- for penicillin and cephalosporin resistant pneumococci: add vancomycin and if necessary rifampicin
- if anaphylaxis to penicillin or cephalosporins, or resistance - chloramphenicol
- Give rifampicin for 2 days to patients treated with benzylpenicillin or chloramphenicol (to eliminate nasopharyngeal carriage)
dexamethasone IV
- 10mg QDS for 4 days
- given shortly before or with 1st dose of AB
- continue in Pneumococcal or H. influenzae meningitis = reduced complications: death (S. pneumoniae) and hearing loss (H. influenza)
- avoid if HIV suspected
resus - ITU
prevention of meningitis
only for meningococcal meningitis
Notify public health services and consult a consultant in communicable disease control for advice regarding chemoprophylaxis (e.g. rifampicin for 2 days) and vaccination for close contacts
vaccination against meningococcal serogroups A and C.
complications of meningitis
septicaemia
shock
DIC
renal failure
fits
peripheral gangrene
cerebral oedema
cranial nerve lesions
cerebral venous thrombosis
hydrocephalus
water-house-Friderichsen syndrome - bilateral adrenal haemorrhage
sensineural hearing loss
impaired vestibualr function
epilepsy
diffuse brain function
px of meningitis
Mortality rate from bacterial meningitis is high (10–40%withmeningococcalsepsis)
in developing countries mortality rate often higher
viral meningitis often self limiting
