Infectious Diseases Flashcards
What is meningitis?
Inflammation of the meninges of the brain. Can be a bacterial, viral or fungal cause.
What are the bacterial causes of meningitis in neonates?
E.coli
Group B Strep
Listeria monocytogenes
What are the bacterial causes of meningitis in infants?
Neisseria meningitidis
H.influenzae
Strep pneumoniae
What are the bacterial causes of meningitis in young adults?
N.meningitidis
Strep pneumoniae
What are the bacterial causes of meningitis in the elderly?
Strep pneumoniae
N.meningitidis
Listeria
What are the viral causes of meningitis?
Mumps virus Echo virus Coxsackie virus Other enterovirus Herpes simplex virus
Risk factors for meningitis?
Immunocompromised Elderly Pregnant Malignancy Diabetes Bacterial endocarditis Crowding Intrathecal drug administration IVDU
How does meningitis present?
TRIAD
- headache
- neck stiffness
- fever
Other:
- meningismus (photophobia, neck stiffness)
- reduced GCS
- papilloedema
- intense malaise, fever, riggers, vomiting
- irritable + prefers to lie still
- meningococcal septicaemia (rash)
- seizures
- progressive drowsiness
- positive Kernig’s + Brudzinki’s sign
If viral may be less signs and more self-limiting
How do you diagnose meningitis?
Blood cultures Bloods: FBC, U+E, CRP, serum glucose CT head Lumbar puncture Throat swabs Serum PCR (pneumococcal + meningococcal)
When do you do a CT before LP?
- > 60 years
- immunocompromised
- Hx of CNS disease
- new onset/recent seizures
- decreasing conscious levels
- focal neurological signs
- papilloedema
What are the LP results for bacterial meningitis?
Cells: polymorphs (neutrophils)
Protein: raised
Glucose: low
What are the LP results for viral meningitis?
Cells: lymphocytes
Protein: normal/raised
Glucose: normal
What are the LP results for TB meningitis?
Cells: lymphocytes
Protein: raised
Glucose: low/normal
How do you treat meningitis?
If non-blanching petechial or purpuric rash = meningococcal septicaemia
> immediate IM benzylpenicillin (community)
> immediate IV cefotaxime (hospital)
+ do not perform LP, confirm diagnosis by blood culutres
If bacterial meningitis:
> IV cefotaxime or IV ceftriazone 2-3g QID
(if Hx of anaphylaxis with penicillin, give IV chloramphenicol)
If viral:
> self-limiting
> aciclovir if cause is HSV
When would you add IV amoxicillin to meningitis treatment? And why?
If bacterial cause and patient is: - immunocompromised - >50 years - pregnant In order to cover listeria.
If the cause is likely pneumoccocal for bacterial meningitis, what could you add to the treatment and why?
Oral dexamethasone to reduce cerebral oedema
What do you do with contacts of meningitis patients?
Prophylaxis for close contacts
> oral ciprofloxacin stat (all ages + pregnancy)
> oral rifampicin (all ages but NOT pregnancy)
What are some complications of meningitis?
Hearing loss
Seizures
Developmental problems
What is encephalitis?
Infection and inflammation of the brain parenchyma which affects the extremes of age (children + elderly.)
What causes encephalitis?
Mainly viral:
- herpes simplex virus 1 + 2
- varicella zoster
- EBV, CMV, HIV
- mumps, measles
Non-viral:
- bacterial meningitis
- TB
- malaria
Clinical presentation of encephalitis?
TRIAD
- fever
- headache
- altered mental status
Begins with features of viral infection (fevers, headache, myalgia, fatigue, nausea) and progresses to personality and behavioural changes, decreased consciousness, confusion + drowsiness
How is encephalitis diagnosed?
MRI
EEG
LP
Blood + CSF serology
How is encephalitis treated?
Viral:
> IV aciclovir immediately (don’t wait for results)
Anti seizure medication
e.g. primdone
If suspected meningitis: IM benzylpenicillin
What causes tetanus?
Clostridium tetani
- soil organism, terminal spores
- gram positive anaerobe
- infects via dirty wounds, releasing toxin which translate via peripheral nerve and enter CNS and bind to GABA receptors of inhibitory inter-neurones.