Meningitis Flashcards
Presence of ___ and ___ are absolute indications to obtaining an imaging study before performing an LP
Presence of papilledema and focal neurologic deficits are absolute indications to obtaining an imaging study before performing an LP
LP analysis for meningitis should include:
- Opening pressure
- Closing pressure
- CSF glucose, protein, total + differential WBC
- CSF gram stain, fungal stain, culture
- Latex particle agglutination, HSV-PCR, EV-PCR, CSF-VDRL
Approach to treating meningitis (without specific abx)
Generally speaking, you want to give empiric abx and acyclovir BEFORE THE DIAGNOSIS IS EVEN CONFIRMED
If you can do a quick blood draw and/or LP first, this may be warranted, as abx can confound serum and CSF cultures
Kernig sign
Pain and resistance to complete extension of the knee when the hip ix flexed in the supine position
Caused by spasm in the hamstring muscles due to inflammation of the lumbosacral roots
Burdzinski sign
An involuntar flexion of the hips and knees upon passive flexion of the neck, which may indicate meningeal irritation
Latex particle agglutination
Surface of latex particles is coated with specific antigens or antibodies, forming “sensitized latex”
When a sample containing complemetary antigens or antibodies is mixed with the sensitized latex, visible agglutination is noted.
Used to detect H. influenzae type B, S. pneumoniae, and N. meningitidis
Enteroviral load must be measured by. . .
. . . RT-PCR
As enteroviruses are ssRNA viruses
Principal causes of bacterial meningitis inside and outside of the neonatal period
Neonatal: Streptococcus agalacticae, Listeria monocytogenes, E. coli
Outside neonatal: S. pneumoniae, N. meningitidis (+ H. influenzae B only if unvaccinated)
Most common causes of viral meningitis in the US
-
Enteroviridae (most common)
- Coxsackie A
- Coxsackie B
- Echoviridae
-
Herpesviridae (less common, but treatable with antivirals)
- HSV
- VZV
- CMV
-
Arborviridae (transmitted via arthropods, usually ticks)
- St. Louis encephalitis virus
- West Nile virus
- Japanese encephalitis virus
- Eastern equine encephalitis virus
- Western equine encephalitis
- La Cross virus
Epidemiology of enteroviral meingitis
Spreads though the fecal-oral route and rarely the respiratory route
Outbreaks are associated pharyngitis and gastroenteritis and typically occur in late summer/early fall.
Syndrome of mild flu-like symptoms, viral exanthem, pharyngitis, gastroenteritis that progreses to meningitis
Full of red flags for enteroviral meingitis, especially Coxsackie meingitis (depending on the distribution of the viral exanthem)
Complications of meningitis
- Thrombotic stroke (due to peri-vascular inflammation)
- Dysphagia/aspiration
- Communicating hydrocephalus
- Non-communicating hydrocephalus
- Venous sinus thrombosis
Meningitis with high fever, widespread maculopapular rash, and presence of purpura/ecchymosis
Neisseria meningitis
Viral vs bacterial meingitis CSF characteristics (Table)
Timeframe regarding antibiotic administration and the sensitivity/specificity of CSF gram stain and culture
While it is optimal to get CSF prior to administering abx from a diagnostic perspective, if you it within 2 hours of starting abx the sensitivity and sensitivity are only mildly reduced.
After 2 hours, the odds start to drop more precipitously
CSF viral culture
Slow and poor sensitivity
PCR-based studies are far superior
Neuroimaging studies in meningitis (bacterial and viral)
Typically normal in both bacterial and viral. However, HSV is a key exception
HSV often shows evidence of hemorrhagic inflammatory damage in the temporal region
Generally, imaging is done in order to rule out non-communicating hydrocephalus for LP rather than for diagnostic purposes
Typical first-line agents for bacterial meningitis
(Penicillin G OR Ampicillin) + 3rd generation cephalosporine (usually ceftriaxone)
Coverage of ampicillin for meningitis-causing bacteria
Ampicillin covers meningococci, listeria, and most pneumococci
Coverage of third generation cephalosporines for meningitis
Ceftriaxone or cefotaxime are the typical agents.
Cover gram-negatives as well as ampicillin-resistant H. influenzae.
When do we add vancomycin to the empiric meningitis antibiotic regimen?
- Vanc is added to cover for Staph aureus when patients ahve undergone recent neurosurgical procedures or had recent head trauma
- If sensitivities of S. pneumoniae strain are unknown, adding vancomycin is also appropriate (as some S. pneumoniae are resistant to third generation cephalosporines)
Coverage of Penicillin G for meningitis
Used to treat gram-negative cocci (Neisseria) and gram-positive bacilli
When do we add aminoglycosides to a bacterial meningitis regimen?
If gramp-positive bacilli or gram-negative bacilli are identified
Meningitis algorithm
Adjuvant therapy with IV corticosteroids in meningitis
Clearly indicated in childhood meningitis, 100% of the time
Less clear for adults, but seems to prevent severe complications and neurologic deficits in S. pneumoniae meningitis.
Notably, there is evidence to suggest that corticosteroids decrease the penetration of vancomycin into the CSF.
A finding of normal CSF glucose is very uncommon in ___ meningitis
A finding of normal CSF glucose is very uncommon in bacterial meningitis
Evolution of CSF findings in viral meningitis
- Early in viral meningitis, a preponderance of neutrophils may be seen in the CSF
- As the illness progresses, a lymphocytic pleocytosis predominates with gradually rising protein
- Glucose remains relatively normal throughout this entire process
H. influenzae B are often described as __ on gram stain
H. influenzae B are often described as gram negative coccobacilli on gram stain
