Meningitis and encephalitis Flashcards
What is the clinical presentation of bacterial meningitis?
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What is the CSF profile of all the causes of meningitis?
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What are the clinical differences btw. Viral and bacterial meningitis?
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What are the most common organisms in viral meningitis?
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How do you differentiate viral encephalitis and viral meningitis?
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What is medical management protocol for bacterial meningitis? (age groups)
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What is the epidemiology of bacterial meningitis?
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What are the most common organisms for bacterial meningitis?
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What’s the goal of bacterial meningitis treatment?
• This is a medical emergency so move fast
• Start appropriate empiric antibiotic therapy within 60 minutes of arrival to ER
○ ASAP
How many bacterial meningitis patients present with the classic symptoms?
• There is the "classic triad" but only 45% of pts. Present with those • 100% present with 2/4: ○ Headache ○ Nuchal rigidity ○ Altered mental status ○ fever
Altered mental status in the context of bacterial meningitis means what?
- Bad news. Severe or advanced case
* Also think encephalitis or brain abscess/empyema
What are the non-classic manifestations of bacterial meningitis?
- Seizures
- Nausea/vomiting
- Myalgias
- Cranial nerve palsies (III, VI, VII, VIII)
- Focal deficits (hemiparesis, ataxia, gase preference)
- Papilloedema in a small percent
What is the pathogenesis of bacterial meningitis?
• Disease of bacteria in the sub-arachnoid space
• Bacteria reach the sub-arachnoid space from :
• Bloodstream (most common)
• Adjacent intracranial infection (sinusitis, mastoiditis, otitis)
• Congential, traumatic or surgical defects in skull/spinal column
○ Endotoxin stimulates TNF and IL-1 release
○ BBB permeability increased
○ Neutrophil (PMN) recruitment which add to purulent exudate and enhance cytotoxic edema via ROS
The causative agents of bacterial meningitis will vary based on what conditions?
- Patient’s age
- Patient’s immune status
- Community acquired vs. nosocomial infection
What organisms are important for the 23month to 34 year meningitis patient population (the largest most common age range)?
- 40% neisseria meningitidis
- 40% streptococcus pneumoniae
- 10% Hemophilus influenzae
- 5% streptococcus agalactiae (group B)
- 1% Listeria monocytogenes
- 1% staphylococcus species
What organisms are important for the 2-23 month meningitis patient population?
- 50% streptococcus pneumoniae
- 15% - Neisseria meningitides
- 15% streptococcus agalactiae (group B strep)
- 10% Haemophilus influenzae
- 2% listeria monocytogenes
- Small percent - staphylococcus species
What organisms are important for the under 2 months patient population?
- Streptococcus agalactiae (group B strep)
- Gram-Negative rods (enterobacteriaceae)
- Listeria monocytogenes
- Streptococcus pneumonia (pneumococcus)
- Hemophilus influenzae
- SMALL PERCENT (0-5%) Neisseria meningitidis (meningococcus)
What are the different age groups that you should group meningitis patients into?
- Under 2 months
- 2-23 months
- 23 months - 34 years
- Over 35 years
What do you need to do in the meantime if you are delaying LP for a CT/MRI?
- Empiric antibiotic treatment STAT
* Blood cultures STAT and start empiric therapy
The protocol for dx of bacterial meningitis is lumbar puncture. When do you NOT do this?
• Though LP is the way to go before even neuroimaging, there are cases where LP is a bad idea right away
○ Reduced level of consciousness (low GCS score)
○ Focal neurologic defitics
○ Papilloedema
○ New onset seizures
○ History of CNS disease or an associated condition
§ Something that increases risk of brain abscess/empyema
○ Immunocompromised pt
What are the important organisms for the over 35 years group of meningitis patients?
• 50-70% - streptococcus pneumoniae • 10-25% Neisseria meningitidis • 1-10% hemophilus influenzae • 10% listeria monocytogenes ○ Though much more common in immune compromised or in pts over 60yrs • 10% gram-negative rods (nosocomial) • Less than 5% group B strep ○ Which is less important apparently as you age
What are the domains of key data to be found in the CSF profile of a CNS infection?
- WBC
- Cell type
- Glucose
- Protein
- Cultures
What is the expected CSF profile for chronic meningitis (TB or fungi)?
• WBC - 10-1K • Cell type - mononuclear • Glucose - low to normal • Protein - VERY elevated • Cultures - Tb, fungi, cryptococci •
What is the expected CNS profile for viral meningitis?
- WBC - 10-2K
- Cell type - mononuclear (lymphocyte)
- Glucose - normal
- Protein - normal or slight elevation
- Cultures - + /-(viral) - (bacterial)
What is the expected CNS profile for bacterial meningitis?
- WBC - 100-10K
- Cell type - PMN (80-95%)
- Glucose - Low (50mg/dL)
- Cultures - + (bacteria)
What is the expected CSF profile for encephalitis?
- WBC - 10-2K
- Cell type - mononuclear
- Glucose - normal
- Protein - elevated
- Cultures - +/- viral or bacterial
What is the expected CSF profile for brain abscess (LP not recommended)
- WBC - less than 200
- Cell type - mononuclear
- Glucose - normal
- Protein - normal or elevated
- Cultures - + bacterial (unless ruptured)
What are the useful stains or other tests for the different meningitis etiological agents?
• Bacterial - gram stain • Viral - PCR • Chronic - AFB (acid-fast), India Ink (for the cryptobacilli) ○ Crypto Ag (probably a ELISA) ○ VDRL - The Venereal Disease Research Laboratorytest(VDRL) is a bloodtestfor syphilis that was developed by the eponymous lab. TheVDRL testis used to screen for syphilis (it has high sensitivity), whereas other, more specifictestsare used to diagnose the disease. ○ TB PCR • Encephalitis - PCR, MRI • Abscess - MRI/CT (head and sinuses)
What is true about the specificity and sensitivity of the gram stain?
• It changes depending on the lab, and certainly depending on the organism • Sensitivity (true positive) - 60-90% • Specificity (descending order) ○ H flu and pneumococcus - 90% ○ Meningococcus ○ Gram negative rods ○ Listeria - 33%
In what percentage of bacterial meningitis patients are bacterial CSF cultures positive?
- 70-85% (unless there was treatment before LP)
* Blood cultures are more like 30-50% positive
Assuming the patient is immunocompetent and they have community acquired disease, what are the empiric treatment choices for: Children and adults?
• 3 months to 50 yrs ○ Ceftriaxone OR ○ Cefotaxime AND vancomycin • Over 50 years ○ Ceftriaxone OR ○ Cefotaxime AND vancoycin AND ampicillin
What is the MRI used for in the meningitis case?
• Can show meningeal enhancement because of inflammation
• More used for searching out complications
○ Cerebral edema, ventriculitis, hydrocephalus, infarction, parameningeal or intracranial focal suppuration
Assuming the patient is immunocompetent and they have community acquired disease, what are the empiric treatment choices for: Neonates and infants?
• Less than 3 months
○ Ampicillin AND cefotaxime
What is the empirical meningitis treatment in nosocomial infections, recent head truama/sugery, immunocompromised and alcoholics?
• Any age!
○ Vancomycin AND meropenem
○ +/- additional ampicillin (for listeria)
Vancomycin is used in nosocomial meningitis infections (and community acquired for that matter) why?
- Covers penicillin/cephalosporin resistant pneumococci and coagulase-negative and MRSA staph
- Also covers enterococcus species
Meropenem is used for nosocomial meningitis infections why?
- Covers pseudomonas and other resistant gram-negative rods
* Cefepime is a common alternative
What tests should CSF pneumococci undergo?
- Though resistance is still fairly rare:
- Test for MICs to penicillin.
- IF AT ALL penicillin resistent then test MICs of cephalosporins (3rd generation)
- IF AT ALL RESISTANT to either or both then repeat LP after 24-36 hours to confirm and document sterilization of CSF culture
How long is the treatment course for bacterial meningitis?
- 7 days for meningococcus and H flu
- 10-14 days for pneumococcus
- 21 days for gram negative species (including neisseria meningiditis)
- 21+ days for listeria
If somebody is worried about a culture being ruined by empirical treatment for bacterial meningitis, what should you remember?
within 4 hours, there is little to no effect either on gram stain or culture results of LP
When would you use steroids in meningitis treatment?
- Steroids can be helpful in strep pneumoniae cases ONLY
- Discontinue if you find another organism
- Admin 10-20 min before 1st antibiotic dose or concurrent with first dose
- NO ROLE after antibiotics have started
What are the common viral causes of meningitis?
• Enteroviruses
• HSV-2
• Arboviruses
○ West nile virus (WNV)
What are the viruses that RARELY cause meningitis?
- Adenoviruses
- CMV
- Influenza A and B
- LCMV
- MMR
- Parainfluenza and rotavirus
What are the less common (intermediate) viral causes of meningitis?
- HSV-1
- EBV
- VZV
- HIV
- HHV-6
What is dx protocol for viral meningitis?
• CSF sample (LP)
• Lymphocytic pleocytosis with normal glucose
○ Exceptions are WNV (PMNs) and low glucose in mumpts, LCMV and HSV2
• PCR amplification of viral genomic material is most specific and important dx test
What antiviral therapies are available for viral meningitis treatment?
- Acyclovir - HSV, VZV
- Antiretrovirals - HIV
- Foscarnet, ganciclovir, cidofovir - CMV
- Rimantidine - flu
- Pleconaril - enteroviruses
- Supportive treatment - WNV
What’s the difference between viral encephalitis and viral meningitis?
• Infection in the brain parenchyma, as opposed to infection in meninges
What are the clinical manifestations of viral encephalitis?
- Altered consciousness, fever, headage
- Seizures and focal neurological signs
- Personality change
- Alteration in mental status
- Alteration in level of consciousness
- Aphasia
- Hemiparesis
- Ataxia
- Cranial nerve palsies
- Visual field loss
- Tremors
- Myoclonus
- Parkinsonism (WNV)
What is the seasonality to viral encephalitis?
• Seasonality in the etiological agent • Summer/early fall ○ Arboviruses (WNV) - most important cause US ○ Enteroviruses ○ Zika virus (fetal) • Fall and winter ○ LCMV - lymphocytic choriomeningitis virus • Winter and spring ○ Mumps • Any season ○ HSV - most important cause US ○ EBV ○ CMV
What are the most important causative agents of viral encephalitis in the USA?
HSV and WNV
Where is west nile virus endemic in the USA?
• Western and midwest states
What is the diagnostic protocol of viral encephalitis?
• CSF pleocytosis
• EEG abnormal (up to 90% of patients)
• CT and MRI are helpful in ID of focal encephalitis and r/o other mimics of disease
• PCR amplification of viral nucleic acid from CSF is gold standard
○ HSV, VZV, CMV, EBV, enteroviruses
• WNV IgM detection in CSF is dx of WNV (better than PCR)
What is the therapy regimen for viral encephalitis?
• Treatment is mostly for herpes viruses ○ Adult HSV ○ Neonatal HSV ○ VZV • All acyclovir *empiric therapy is acyclovir
What are the clinical features of Bacterial meningitis?
• Classic triad (only 45% patients have the classic triad though)
○ Fever, headache and neck stiffness (nuchal rigidity/meningismus)
• 100% of patients have at least 2 of the 4 symptoms
○ Fever, Headache, nuchal rigidity, altered mental status
