CNS Infections Flashcards
List 7 types of CNS infections
Encephalitis, Meningitis, Meningoencephalitis, Encephalomyelitis, Epidural abscess, Neuritis, Sepsis syndrome due to infection elsewhere (indirect)
What is the difference between meningitis and encephalitis?
Encephalitis involves inflammation of brain parenchyma
How is meningitis classified? (5)
Acute pyogenic (pus forming) meningitis, Acute aseptic meningitis, Acute focal suppurative infection, Chronic bacterial infection, Acute encephalitis
What is the most common microbial cause of acute pyogenic meningitis?
Bacterial
What is most common microbial cause of acute aseptic meningitis?
Viral
Give 3 examples of acute focal suppurative infections
Brain abscess,
Subdural empyema,
Extradural empyema
Give an example of a chronic bacterial infection of meningitis
TB
How does pyogenic meningitis present in pathology?
Thick layer of suppurative exudate covering the leptomeninges (arachnoid and pia mater) of surface of brain
How does pyogenic meningitis present microscopically in histology?
Neutrophils in the subarachnoid space
What are the 4 bugs found in bacterial meningitis? Which is very rare?
Strep pneumoniae,
Neisseria meningitidis,
Listeria monocytogenes,
Haemophilus influenzae - very rare
What type of bacteria is strep pneumoniae?
Gram +ve diplococci
What type of bacteria is neisseria meningitidis?
Gram -ve diplococci
What type of bacteria is listeria monocytogenes?
Gram +ve bacilli
What type of bacteria is haemophilus influenzae?
curvilinear gram -ve bacillis
Immunosuppressed patients of very young or people >60 tend to get which type of bacterial meningitis?
Listeria monocytogenes
Which bacterial meningitis used to mostly be in children but has been mostly eradicated by vaccines?
Haemophilus influenzae
Secondary attack
Neisseria meningitidis
What is treatment for patients with strep pneumoniae, neisseria, haemophilus influenzae?
Ceftriazone IV 2g bd and dexamethasone IV 10mg qds
What is treatment for patients with listeria bacterial meningitidis?
Ceftiaxone IV 2g bd + dexamethasone IV 10g qds + amoxicillin IV 2g 4ourly
If needing to add listeria cover and patient has penicillin allergy, what is treatment?
Co-trimoxazole IV
How long continue antibiotics for each bacteria: strep, neisseria, haem, listeria?
Strep: 5 days ceftriaxone
Neisseria: 10 days ceftriaxone
Haem: 10 days ceftriaxone
Listeria: 21 days amox
If patient has travelled to country with high rates of penicillin resistant pneumococci (e.g. Canada, China, Poland, Spain, USA, Mexico, Italy, Greece, Turkey, Croatia, Pakistan), what is treatment?
Ceftriaxone IV + dexamethasone IV + vancomycin IV or rifampicin IV/PO
Which patients should steroids be given to, how much?
ALL patients suspected of bacterial meningitis - 10mg IV 15-20mins before or with first dose of antibiotic
Giving what drug reduces unfavourable outcome from 25% to 15% and mortality from 15% to 7%?
Steroids
When should you NOT give steroids meningitis? (4)
Post-surgical meningitis,
severe immunocompromise,
meningococcal septic/septic shock,
hypersensitivity to steroids
Which bacteria has most striking benefit from steroids in menigitis?
Strep pneumonia (pneumococcal meningitis) so if not that can stop steroids
Viral meningitis is common and usually occurs in late summer/autumn. What type of viruses tend to cause viral meningitis?
Enteroviruses
What is important to ask about in history of someone with viral meningitis?
Travel history
List 3 diagnostic tests for viral meningitis and which is best?
Viral stool culture,
Throat swab PCR,
CSF PCR - best one
What is treatment for viral meningitis?
Supportive as self limiting e.g. fluids, paracetamol
What is difference between encephalitis and meningo-encephalitis in terms of presenting symptoms?
Meningo-encephalitis displays normal meningitis symptoms of headache, fever and neck stiffness PLUS features of encephalitis
Outline symptoms of encephalitis (6)
Cerebral cortex is diffusely involved so INSIDIOUS onset of
mental status changes,
reduced consciousness/coma,
Confusion, psychosis,
Seizures,
behavioural and speech disturbances,
focal/diffuse neurologic signs e.g. partial paralysis
List 3 investigations for encephalitis
Lumbar puncture,
EEG,
MRI
What virus would you think about if patient presents with insidious onset of overall brain dysfunction symptoms i.e. everything dimmed?
Herpes simplex virus
If delay in diagnosis but you are suspicious patient has viral encephalitis what treatment should be started pre-emptively?
Aciclovir
How does HIV CNS infection normally present?
Meningitis
What is ADEM and when can it occur? (2)
Acute disseminated encephalomyelitis - post flu/vaccine
List 8 common symptoms of CNS infection
Headache, Vomiting, Pyrexia, Neck stiffness, Photophobia, Lethargy, Confusion, Rash
Bacterial meningitis caused by which bacteria is very common with a cribiform plate fracture?
Strep pneumoniae
Bacterial meningitis caused by which bacteria is can occur with neurosurgery/head trauma?
Staphyloccous,
Gram negative bacilli
Strep pneumoniae and neisseria are common causes of bacterial meningitis in all age groups but strep is more common in young and neisseria more common in older. True/false?
False - is common in all age groups but neisseria more common in young and strep more common in older
What percentage of people who survive an initial diagnosis of meningitis with sepsis will live with after-effects e.g. limb loss, deafness, blindness, cerebral palsy, quadriplegia and severe mental impairment?
25%
What causes the complications of meningitis? (5)
Purulence - pus clusters at base of brain and around nerves (especially CN III, VI), Invasion - abscesses, Cerebral oedema, Ventriculitis, hydrocephalus
List 3 types of pathogenesis of bacterial meningitis
Nasopharyngeal colonisation,
Direct extension of bacteria e.g. sinusitis, mastoidis and goes into brain,
From remote infection e.g. endocarditis (rare)
Who should undergo CT prior to lumbar puncture? I.e. who should not get lumbar puncture straight away - warning signs (8)
Immunosuppressed people, History of CNS disease, New onset seizure, (within 1 week) Papilloedema, Abnormal levels of consciousness, Shock, Bradycardia/hypertension, Focal neurologic deficit
CSF results are 99% predictive of bacterial meningitis if:
CSF WBC count is very very high (>2000) and is mostly neutrophils (>1180), high protein and glucose in CSF a lot lower than serum because has been consumed
Where is meningitis belt? (Meningococcus)
Across middle of west africa piece to east side
Outline differences in CSF results between viral and bacterial in terms of cell type, cell number, gram stain, protein, glucose
Cell type: bacterial polymorphs and viral lymphocytes
Cell number: bacterial loads and viral less
Gram stain: bacterial positive and viral negative
Protein: bacterial high and viral normal/slightly high
Glucose: very low compared to BG, usually normal
If no clear diagnosis from LP, stool and throat swabs, opening pressure, culture what additional tests can be done?
165 rRNA PCRs on CSF if bacterial seems likely,
CSF PCR for HSV1 and 2, zoster, enterovirus, stool and throat enterovirus PCR if viral seems likely
How could you tell TB from viral/bacterial from CSF sample?
Cell count and type is same as viral (so lower)and is also lymphocytes but protein levels high and glucose levels low compared to blood glucose
Symptoms of meningococcal meningitis are due to what from the bacteria?
Endotoxin
What form of meningococcal infection presents with big deep purple purpuric rash that won’t blanch when pressed on?
Fulminant septicaemia.
Meningococcal bacteria colonises the nasopharynx and around 10-25% of people carry it with no symptoms. True/false?
True
Which are the more common capsular groups of meningococcus in UK?
B, C, W and Y
TB meningitis is subacute illness. True/false?
True
What is aseptic meningitis?
Meningitis where no bacteria found
Contact prophylaxis treatment?
500mg single dose oral ciprofloxacin
In management of bacterial meningitis with low GCS (<12) or fluctuating conscious level (fall >2) what is management?
Admit, Airway and high flow O2, IV ceftriaxone +/- amoxicillin, IV steroids, Do not wait for CT scan/LP!!
