Meningitis Flashcards
Define Meningitis
Inflammation of the meningeal/leptomeningeal (pia mater and arachnoid) coverings of the brain, most commonly due to infection
Aetiology of Meningitis
Bacterial:
Neonates: Group B streptococci, E. coli, Listeria monocytogenes
Children: Haemophilus influenzae, Neisseria meningitidis, S. Pneumoniae
Teenagers: Gram -ve diplococci = Neisseria meningitides
Adults: Neisseria meningitidis (meningococcus), S. pneumoniae, TB
Elderly: S. pneumoniae, Listeria monoyctogenes
Viral: Enteroviruses, mumps, HSV, VZV, HIV
Fungal: Crytptococcus
Other: Aseptic meningitis, Mollaret’s meningitis
What infectious causes of meningitis are associated with the following:
Extended labour, infection in the previous pregnancy
Late neonatal infection
Gram -ve diplococci in children and teenagers
Unvaccinated children and teenagers
Gram +ve cocci in adults
Elderly, cheese/unpasteurised milk, alcoholics
Extended labour, infection in the previous pregnancy: Group B streptococcus
Late neonatal infection: E. coli
Gram -ve diplococci in children and teenagers: Neisseria Meningitides
Unvaccinated children and teenagers: H. influenzae
Gram +ve cocci in adults: Streptococcus pneumoniae
Elderly, cheese/unpasteurised milk, alcoholics: Listeria monocytogenes
Risk factors for Meningitis
Close communities e.g. dormitories Basal skull fracture Mastoiditis Sinusitis Inner ear infections Alcoholism Immunodeficiency Splenectomy Sickle cell anaemia CSF shunts Intracranial surgery Recent travel and exposure (rodents, ricks, mosquitos, sexual activity)
Symptoms of Meningitis
Meningism (headache, neck stiffness, photophobia) Non-blanching rash (N. meningitides) Fever Neck or backache Irritability Drowsiness Vomiting
Children: high pitched crying or fits
Signs of Meningitis on examination
Meningism: photophobia, neck stiffness
Kernig’s sign = pain/resistance on passive knee extension with hips flexed
Brudzinski’s sign - flexing the neck causes automatic flexion of the hips and knees
Fever
Tachycardia
Hypotension
Skin rash (petechiae with meningococcal septicaemia)
Altered mental state (reduced GCS)
Investigations for meningitis
Blood cultures (2 sets within 1 hour of arrival at hospital and prior to giving antibiotics): positive CT: normal (exclude mass lesion or raised ICP before LP) LP: depends on the cause, send for MC+S
Petechiae scrapings: +ve
FBC: Leucocytosis, anaemia, thrombocytopenia
PCR: +ve for specific antigen
Glucose: Check for metabolic abnormalities
U+Es: Acidosis, hypokalaemia, hypocalcaemia, hypomagnesaemia | low sodium may indicate tuberculous meningitis
VBG: Elevated lactate
LFTs: metabolic abnormalities
Coagulation screening: evidence of DIC
Describe the CSF in bacterial, viral and TB meningitis
Bacterial: Cloudy/turbid, raised polymorph neutrophils, glucose low, protein high
Viral: clear, raised lymphocytes, normal glucose and protein
TB: Fibrin web, raised lymphocytes, glucose low, protein high
Management for Meningitis in primary care
IV/IM benzylpenicillin and urgent hospital referral
Management for Meningitis
- ABCDE: Give oxygen, check airways, crystalloid fluids,
- Take blood cultures
- IMMEDIATE IV/IM antibiotics
a. 3rd gen cephalosporin (cefotaxime 2g qds, ceftriaxone)
b. Benzylpeniciliin
c. Amoxicillin + gentamicin / ampicillin for Listeria
d. Acyclovir for ?encephalitis
e. Add vancomycin and rifampicin if penicillin and cephalosporin resistant pneumococci - Dexamethasone shortly before or with the first dose of antibiotics
a. Continue win pneumococcal or H. influenzae (avoid if HIV suspected)
b. 10mg IV - Resuscitation
a. Patients best managed in ITU
Signs of increased cranial pressure or shift of brain -> ICU
Complications of Meningitis
Hearing loss Septicaemia Impaired mental state Shock DIC Renal failure Fits Peripheral gangrene Cerebral oedema Cranial nerve lesions Cerebral venous thrombosis DVT Hydrocephalies Water-house-Friderichsen syndrome (bilateral adrenal haemorrhage)
Prognosis for meningitis
Mortality rate is high (10-40% meningococcal sepsis)
Mortality rate is often higher in developing countries
Viral meningitis is self-limiting
Outcome is excellent with prompt and adequate antimicrobial and supportive therapy
