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Flashcards in Meningitis and encephalitis Deck (53):

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


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?

• 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 Laboratory test(VDRL) is a blood test for syphilis that was developed by the eponymous lab. The VDRL test is used to screen for syphilis (it has high sensitivity), whereas other, more specific tests are used to diagnose the disease.
• 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
• Influenza A and B
• Parainfluenza and rotavirus


What are the less common (intermediate) viral causes of meningitis?

• HSV-1
• 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


What are the most important causative agents of viral encephalitis in the USA?



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
• 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

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