CNS Infections Flashcards
Patient with fever, headache, neck stiffness, photophobia.
Brudzinski and Kernig negative
How useful is this information?
Does not exclude bacterial meningitis.
Fever/ headache/ photophobia/ neck stiffness more sensitive
Kernig - bend knee, extend leg, worse pain in neck
Brudzinski - supine patient, lift head off bed - legs will flex off bed
Patient with fever, headache, neck stiffness, photophobia.
Do they need CT before LP?
Only CT if -
GCS 12 or less
seizures
focal neurological deficit
severely immunocompromised
Patient with fever, headache, neck stiffness, photophobia.
Started on antibiotics and steroids
CSF
WCC 450
Protein 1500
Glucose 1
Microscopy shows gram positive diplococci
What is pathogen?
Strep pneumoniae
60 year old patient with fever, headache, neck stiffness, photophobia.
Started on antibiotics and steroids
CSF
WCC 450
Protein 1500
Glucose 1
Which antibiotics should be used?
Ceftriaxone + amoxicillin
to cover for listeria in age group
If identify strep pneumoniae as cause, can step down to benzylpenicillin
What is role of corticosteroids in meningitis?
- Strep pneumoniae - small reduction in mortality
- Haemophilus - less severe hearing loss in children
Patient with fever, headache, neck stiffness, photophobia.
Started on antibiotics and steroids
CSF
WCC 450
Protein 1500
Glucose 1
Microscopy shows gram positive diplococci - pneumococci
Should pneumococcal isolate be sent for serotyping?
Yes
helps identify pattern of strains, and whether they are covered by routine vaccination schedule
Patient with fever, headache, neck stiffness, photophobia.
Started on antibiotics and steroids
Microscopy shows gram positive diplococci - pneumococci
Should patient be vaccinated to prevent further episodes of invasive pneumococcal disease?
Yes - if not vaccinated in past 5 years
Patients >65, and those with chronic disease, will be routinely vaccinated
What are treatment options for strep pneumoniae?
Penicillin susceptible
Penicillin resistant
Cephalosporin resistant
Penicillin susceptible - benzylpenicillin
Penicillin resistant - ceftriaxone
Cephalosporin resistant - vancomycin + rifampicin
What is duration of treatment of each infection?
Strep pneumoniae
Neisseria meningitidis
Haemophilus
Listeria
Strep pneumoniae - 14 days
Neisseria meningitidis - 7 days
Haemophilus - 10 days
Listeria - 21 days
45 year old, 5 day history of fever, fatigue. Last 24 hour erratic behavior, and had a seizure.
Temp 38degC
GCS 13
What is differential diagnosis?
encephalitis - HSV causes 50% of cases
SOL
vascular event
45 year old, 5 day history of fever, fatigue. Last 24 hour erratic behavior, and had a seizure.
Temp 38degC
GCS 13
Patient is immunocompromised.
What rarer differential diagnoses need to be considered?
HHV6
CMV
EBV
Acanthomoeba -
- Balamuthia mandrillaris 90% mortality
- Naeglaeri Fowleri
Syphilis
Cryptococcus
TB
Patient with AML, presents with fever, headache, seizure. CT shows possible abscess
What is empirical treatment?
Ceftriaxone and metronidazole
consider anti-fungal such as ambisome or voriconazole as immunosuppressed
Patient with AML, presents with fever, headache, seizure. CT shows possible abscess
Patient keeps ornamental fish at home, lives in countryside.
Recently treated for otitis media by GP
What are possible causes of abscess?
Nocardia - filamentous gram positive species, part of normal human flora.
Also found in soil/ water - so pond may explain cause
Can occur in immunocompetent, but most occur in immunocompromised
First line treatment is co-trimoxazole for 6-12 months
18 year old presents with headache, vomiting, and eventually reduced GCS.
Brain imaging shows mass in pineal gland, with associated haemorrhage and hydrocephalus
Neurosurgery evacuate of blood, and insert extra-ventricular drain (EVD)
3 days later he develops fever
What are possible sources?
Chest - was intubated
Urine - catheter
Lines
EVD
Can be normal body response to bleeding/ surgery. If fever associated with tachycardia/ hypotension, more likely to be caused by infection
18 year old presents with headache, vomiting, and eventually reduced GCS.
Brain imaging shows mass in pineal gland, with associated haemorrhage and hydrocephalus
Neurosurgery evacuate of blood, and insert extra-ventricular drain (EVD)
3 days later he develops fever
CSF from EVD WCC 320 polymorphs 200 lymphocytes 120 RCC 6400 No organisms gram stain Glucose 6.4 Protein 0.6
Should antibiotics be started before culture results are available?
Decision complicated by elevated protein/ RCC/ WCC from recent neurosurgical procedure
If patient unstable - treat for meningitis, until alternative diagnosis found.
This may include repeat CSF sampling at 48 hours
Most common cause is staph aureus, including coagulase negative staph.
Consider IV antibiotics such as ceftriaxone, and intrathecal antibiotics such as vancomycin
18 year old presents with headache, vomiting, and eventually reduced GCS.
Brain imaging shows mass in pineal gland, with associated haemorrhage and hydrocephalus
Neurosurgery evacuate of blood, and insert extra-ventricular drain (EVD)
3 days later he develops fever
CSF from EVD WCC 320 polymorphs 200 lymphocytes 120 RCC 6400 No organisms gram stain Glucose 6.4 Protein 0.6
culture grows coagulase negative staph
What are next steps?
If no other source, consider it pathogenic.
Repeat cultures to confirm this
remove EVD, as poor response with antibiotics alone. Replace EVD at different site if still required for intracranial pressure management
usually give antibiotics from 7 days after last negative culture
18 year old presents with headache, vomiting, and eventually reduced GCS.
Brain imaging shows mass in pineal gland, with associated haemorrhage and hydrocephalus
Neurosurgery evacuate of blood, and insert extra-ventricular drain (EVD)
Treated for EVD infection.
Biopsy of pineal gland shows germinoma. Starts chemotherapy. Five days late becomes GCS 8, and unwell. Yeasts seen on CSF
Candida parapsilosis found on culture
What are next management steps?
liposomal amphotericin B
Once improved, switch to oral fluconazole
removal of device - either re-insert EVD, or use temporary lumbar drain. Only re-insert once culture is negative after treatment
Advanced HIV, not on treatment. Progressive confusion.
MRI shows diffuse white matter changes, with lesions.
What are differentials?
PML - JC virus
toxoplasmosis
lymphoma
How to diagnose PML?
MRI
brain biopsy - rarely done
CSF - JC virus PCR
Advanced HIV, not on treatment. Progressive confusion.
MRI shows diffuse white matter changes, with lesions, thought to be PML.
Patient subsequently started on ART. Initial improvement, then deteriorates. MRI shows areas of oedema around noted previous demyelination
What is explanation for this?
immune reconstitution syndrome (IRIS) - can be associated with JC virus
CD4 cells recover, and immune system stimulated
can lead to headache, neurological deficits, seizures
ART is treatment for JC virus
also see JC virus infection in immunocompromised e.g haematological conditions, patients on monoclonal antibodies e.g natalizumab
What treatment is available for IRIS due to JC virus infection?
corticosteroids
TB meningitis
Which drugs cross BBB freely?
Isoniazid
Pyrazinamide - to lesser extent
Patient with meningitis bacterial.
Why is glucose usually low?
Neutrophils use glucose for energy, for phagocytosis.
Bacteria very minimally “use it up”
Why is alcohol abuse/ liver cirrhosis strongly associated with S.pneumoniae meningitis?
Alcohol suppresses cough reflex - allowing bacteria into alveolar spaces
Alcohol reduces ciliary clearance
Alcohol reduces neutrophil recruitment
Why does Cryptococcus stain gram variable in CSF?
Capsule may stain gram neg, while yeast cell stains gram pos
Use India ink stain
CrAg does not distinguish between Cryptococcal neoformans, and Cryptococcal gattii
What are differences in clinical picture?
Cryptococcal gattii -
- more likely to infect immunocompetent, but still infects immunocompromised
- more likely cause pulmonary disease
Patient comes in unwell, with apparent sepsis.
Give broad spectrum antimicrobials.
Patient deteriorates further. Thought to have botulism
Which antimicrobial class contra-indicated in boutlism infection?
Aminoglycosides may exacerbate the symptoms of botulism by competitive inhibition of the presynaptic portion of the neuromuscular junction and by decreasing acetylcholine release from nerve terminals.
Therefore in patients with ptosis/ hypotonia and unwell, use of aminoglycosides should be avoided until the diagnosis of botulism can be ruled out
Patient with PML
What are possible treatment options?
Stop immunosuppression/ start ARVs - although can cause IRIS, which may need steroid treatment
Mirtazipine shows some benefit
Cidofovir/ mefloquine/ cytarabine all been used with minimal benefit
