CNS Infections Flashcards
Define meningitis
Infection in sub arachnoid space of the LEPTOmeninges
Clinical features in infant with meningitis
Bulging fontanelle, crying, poor feeding
Non blanching rash
Headache, neck stiffness, fever vomiting etc…
CSF findings in viral meningitis (lymphocytes, neutrophils, glucose, protein)
Lymphocytes: High
Neutrophils: Low
Glucose: normal
Protein: Slightly elevated
CSF findings in bacterial meningitis (lymphocytes, neutrophils, glucose, protein)
Lymphocytes: Slightly raised
Neutrophils: Very raised
Glucose: Very low
Protein :elevated
CSF findings in TB meningitis (lymphocytes, neutrophils, glucose, protein)
Similar to virus except glucose is low and ziel neelson is +ve
Cause of intracellular meningitis?
Neisseria meningitidis
Cause of intercellular meningitis?
Haem. influenzae
How do neisseria men. and H. influenze overcome the immune system to cause meningitis?
Polysaccharide capsules are able to evade complement system in blood
Once in CNS, there is no complement system so they grow unimpeded
How is the BBB broken down in meningitis? (recognise)
Bacteria replicate and lyse
This causes release of interleukins IL1, IL6 and TNF
Polymorphs are attracted to infection site
THis causes endothelial disruption, albumin leak, and CEREBRAL OEDEMA!!
Most common causes of meningitis in infants?
Group B strep
E coli
Listeria
Most common causes of meningitis in toddlers
N. meningitis
Strep pneumoniae
H influenzae
Most common cause of meningitis in adults
N. meningitidis
S. pneumoniae
(H. influenzae less common)
What are the ‘NHS’ bacteria?
Neisseria meningitis
H. influenzae
Strep pneumonia
Who gets neisseria meningitis? What is it sensitive to?
Children and YAs
Penacillin
Who gets H. influenzae? What is it resistant to?
Young kids
B lactamase +ve, so penicillin resistant
Who gets strep pneumoniae? What is is resistant to?
Extremes of age
Starting to see penicillin resistance
What type of organism is strep pneumoniae? What do you see on blood agar?
Gram +ve diplococci
Draughtsman colony, green zone of haemolysis
What type of organism is Haemophilis influenzae?
Gram negative rod
Culturing requirements for H influenzae?
Needs X and V factors
Grows best on enrichment media eg chocolate agar
Smells like semen lol
Invasive strains are often capsulated.
Diseases caused by H influenzae?
Pneumonia
Meningitis
Epiglottitis
What type of organism is neisseria meningitidis?
Gram -ve diplococcus
Culturing features of neisseria meningitis?
Oxidase positive
IDENTIFIED SUGAR FERMENTATION
MeninGos do Maltose and Glucose!
Treatment of meningitis for adults and children
Ceftriaxone (/benzylpenicillin)
Treatment of meningitis in infant?
Ampicillin + cefotaxime
What immunotherapy can be used for meningitis?
Dexamethasone before antibiotic may decrease cerebral oedema in children
What does Hib/menC vaccine protect against?
H influenzae and meningococcal meningitis group C
Describe Hib vaccine components (recognise_
PRP polyribosylribitol phosphate
T cell independent (no IgG boost)
New meningitis vaccines? (3)
New conjugate meningococcal group C
Meningococcal polysaccharide A, C (not B neisseria)
Pneumococcal 7 valent vaccines
Which meningitis is not protected against with vaccines?
Group B Neisseria meningitis
Prophylaxis for meningitis if there is an unimmunised child under 4 in the household?
Rifampicin
Prophylaxis for menigitis?
Ciprofloxacin for all close contacts in past 10 days
Viral causes of meningitis?
Enteroviruses -80%
Also: HSV 2 (and 1) VSV, CMV Mups Adenovirus HIV
Examples of enteroviral causing meningitis?
Coxsachie or echovirus most common
Treatment of viral meningitis?
SUPPORTIVE
Anti-HSV not proven
May be preventable by vaccination
Prognosis of viral meningitis?
Better than bacterial
Non-viral causes of aseptic meningitis? (i.e couldn’t culture anything or use PCR identification)
Fungi TB!!! Syphillis Brucella Mycoplasma Protozoa Helminths
Age group affected by TB meningitis?
<6 yrs
How does TB meningitis present?
3-6 months after initial infection/exposure
Millary TB in 50%
GRADUAL ONSET:
- personality change, irritability
- FEVER, drowsiness, neck stiffness
- decreased LOC
**Tests for TB meningitis?
+ve TUBERCULIN test
+ve Mantoux
CSF clear and similar to viral CSF except with low glucose
Hard to diagnose under microscope as bacilli are scarce
Can also look at gastric washings
Prognosis of TB meningitis?
Poor
Treatment of TB meningitis?
4 drugs, RIPE for 10 months, then cute down to RI
Organisms causing meningitis
in immunocompromised host?
Listeria in raw mik or soft cheese
Cryptococcus yeast
Causes of encephalitis? (8)
MAINLY VIRAL
HSV 1 (most common)
Also:
- Influenza
- VSV
- Enteroviruses
- Rabies
- Arboviruses
- Hendra and Nipah viruses
- Japenese B
Non viral causes of encephalitis? (9) (recognise)
N. meningitidis Listeria monocytogenes Scup typhus Leptospirosos Melliodosis
Malaria
TB
Borrelia and Brucella
Investigations and management of encephalitis
High dose aciclovir and abx if high suspicion
CSF
THroat and stool samples
INeural imaging, EEG
Most common cause of encephalitis?
HSV 1
Causes 1-4 cases per million per year
80% of those untreated will die
Clinical features of HSV1 encephalitis
Headache Fever Decreased LOC Confusion Dysphasia
Treatment of HSV 1 encephalitis?
Aciclovir 14-21 days
CNS complications of measles
Post infectious encephalitis (autoimmune)
Measles Inclusion body encephalitis (immunocompromised)
*** SSPE, Subacute sclerosing panencephalitis several years after exposure in children (progressive neurodegenerative condition)
3 main types of demyelinating encephalopathies?
All are viral
- Measles, SSPE, MIBE
- Progressive multifocal encephalopthy by JC virus in AIDS
- Rubella encephalitis
What does the JC virus cause in the CNS of AIDS patients?
Progressive multifocal encephalopathy, a demyelinating disease
Clinical features of a brain abcsess
Varied!
Headache, drowsiness, confusion
Seizures
N + V
Motor/sensory impairments
Papillodema and ataxia
Causes of brain abscesses?
Contiguous suppurative focus 40-50% (otitis media or another infection crossing into CNS)
Haematogenous spread from distant infection 25%
Trauma 10%
Common causes of brain abscess
Often polymicrobial
Staph aureus Streptococci Bacteriodes Fusobacterum Pseudomonas etc
Need to look at infection sourse
Tx for abscess with unknown cause?
Cover for streptococci with penicillin or cefotaxime or ceftriaxone
Tx for brain abscess causesd by staph aureus
Vancomycin
Tx for brain abcess caused by pseudomonas aeruginoas
Cefepime or ceftazidime
Tx for brain absess in HIV patient?
May need to consider cover for organisms like Toxoplasma
3 examples of prion diseases
Sporadic CJD (dementia, ataxia, can detect 14-3-3 protein in CSF)
Familial Transmissable Spongiform Encephalopathies TSE (autosomal dominant)
Kuru
Another name for bovine spongiform encephalopathy?
New variant CJD
mad cow disease, not spordaic
Which prion disease has 14-3-3 protein in CSF?
New variant CJD
Also see a high T2 signal in post thalamus at MRI
Plaques on the brain
Who gets new varieant CJD?
Younger patietns
60% have psychiatric symptoms initially
