CNS infections Flashcards
Name the different routes of CNS infection?
- blood-borne
- parameningeal supparation (otitis media)
- defect in dura (direct spread)
Which are the main organisms causing meningitis and which age group do they affect most?
- N. meningitidis (meningococcus) : children/young adults
- S. pneumoniae (pneumococcus): elderly/children <2/immunocompromised (e.g. splenectomy)
- Hib - rare - young under 5
- E.coli/listeria/group b strep: babies
What are the signs of meningitis in children?
Flaccid
Lack of feeding
bulging fontanelle
febrile fit
What are the two signs of meningeal irritation of the motor roots?
Kernig’s sign (spasm when bending leg)
Brudzinski’s sign (flexion of neck, flexion of hips and knees)
What is menigococcal disease?
Meningitis + septicaemia
What are some of the risk factors for poorer outcome with meningitis?
Older age
Otitis media
Lower GCS
Absence of rash
How would you diagnose meningitis?
Lumber puncture - CSF sample
increased WCC, low glucose level
What is important for antibiotics treating meningitis?
bactericidal!
shorter treatment course
Treatment strategy for meningitis?
- Antibiotics
- Anti-convulsants
- Adequate oxygenation
- Prevention of hypoglycaemia
- reduce ICP
Name the different antibiotics used to treat meningitis?
Benzylpenicillin
Ceftriaxone/Cefotaxime
Chloramphenicol
Which antibiotic forms the first line treatment for meningitis?
Ceftriaxome - longer half life, dose less often
Cefotaxime
Advantages and diasdvantages of chloramphenicol?
When is likely to be used?
Advantage: best penetration into the CNS
Disadvantage: bacteriostatic, resistance has emerged amongst Hib, pneumococci
likely to be used when patient is allergic to other treatment options
Empirical treatment for meningitis of unknown cause?
Ceftriaxone/Cefotaxime
+ amoxicillin: if over 60 or immunocompromised
Most common organism cause of brain abscess?
streptococcus milleri
Treatment for brain abscess?
(dental or sinus source) Ceftriaxome + Metronidazole
Which antibiotics are recommended to treat meningitis caused by n. meningitidis?
Benzylpenicillin
C or C
If a patient presents with meningitis but is allergic to penicillin, what are the treatment options?
Dependent on the severity of the allergy, some patients with a penicillin allergy will also react to cephalosporins - in which cases, we can no longer use Ceftriaxone or Cefotaxime
but: Chloramphenicol is then an option
What would you expect to see from a CSF sample of a patient with bacterial vs viral meningitis?
Bacterial:
low glucose
WCC: high neutrophil
increased protein
Viral:
normal glucose
WCC: high lymphocyte
increased/normal protein
What is the usual duration of antibiotic treatment for meningococcus vs pneumococcus?
meningococcus: 7 days
pneumococcus: 14 days
What is the advantage of using Ceftriaxone?
longer half-life
shorter dosing