Meningitis Flashcards
What is Meningitis?
An inflammation of the membranes that surround the brain and spinal cord
Where is meningitis
Involves arachnoid, pia mater, and CSF
What causes Meningitis?
Infection Tumors stroke trauma
What is bacterial meningitis
Acute meningeal inflammation caused by bacterial infection
Generally evokes a PMN response within the CSF
What is aseptic meningitis?
Meningeal inflammation without evidence of bacteria
How does bacterial meningitis happen
Protection to the brain
* the meninges
* skull
* The blood-brain barrier
* The blood-CSF barrier
What is the issue with the BBB?
Host defense mechanisms
What is the patheogenesis?
Hematogenous, contiguous, and direct inoculation
What is the general pathogenesis of
- mucosal colonization and bacterial invasion of the host and CNS
- Bacterial replication in subarachnoid space
- inflammation/ pathophysiologic changes
- Increased intracranial pressure, cerebral edema and neuronal damage
What is the inflammatory cascade?
Cytokines are released
Cytokines promote migrations of neutrophils into the CSF
Neutrophils release PGs, matrix metalloproteinases, etc. that cause edema and swelling
What are the risk factors for meningitis?
Traumatic defects
Previous viral infeciton
Age Elderly 60 years, young children <5 years especially infants
Low socioeconomic status, crowding
Exposure to pathogens?
Recent colonization
Contact with meningitis patient
Bacterial endocarditis
IV drug use
Surgery or trauma
Splenic dysfunction
Immunosuppression
What is unique about the CSF?
Flows unidirectionally from vnetricles to subarachnoid space then down through the spinal cord.
What colour is the CSF?
Normally clear with very few WBCs; proteins that are small, and has about 50-60% of simultaneous peripheral glucose
What are the most common pathogens for infants and neonates with respect to meningitis? <1 month
What are the common pathogens for infanfs and kids 1-23 months
What is the common pathogen for 2-50 years old for meningitis?
What is the common pathogens for Surgery/trauma
What is the most common pathogens for Brain abscess?
Which pathogen is most common for meningitis? In order (4)
Which pathogen use to account for about 50% of meningitis cases?
H. Influenzae
What is the classic triad of Meningitis symptoms?
Headache, Fever, and neck stiffness
What are the other signs and symptoms of meningitis
Altered mental status
Malaise
Seizures
Vomiting
What can be evaluated in patients with suspected meningitis?
Classic triad only in 25-50%
Stick neck only present ~30% of the time
Seizures occur in 5 to 28% adults and 1/3 of kids
Laboratory tests
Lumbar puncture
CSF gram stain and culture
CSF chemistry
CSF WBC counts and differential
What is checked for in the CSF lumbar puncture?
- To obtain fluid for cell counts
- For gram stain and C & S
- The opening pressure and appearance is noted
- Must be careful or even not do puncture with elevated intracranial pressure
What is the CSF gram stain?
May be negative (ex. if patient was recently on antibiotics for AOM)
Will need to start empirical antibiotics until the infecting pathogen is identified –
considered a medical emergency; begin antibiotics within 1 hour of diagnosis
What is being looked at the CSF WBC count and differential
- Normally < 5 WBC x 106/L; mostly monocytes
- In bacterial meningitis – often >500 WBC x106/L; mostly PMNs
- May not see anything out of the ordinary if patient is immunocompromised
What are some other things that should be monitored?
- Check for antibodies towards certain bacteria
- CSF lactate levels – increased in infection
- Check for endotoxins of bacteria
- Electrolytes
What is the treatment considerations for meningitis?
Adequate concentration of antibiotics in the CSF
Not all drugs cross the BBB
Efflux pumps are inhibited
With respect to Adequate concentration of antibiotics in the CSF what should be considered?
Lipid solubility, plasma protein binding, molecular weight and ionizaton
Antibiotic penetration will increase with inflammation
(Do not decrease dose as patient gets better as penetration is going to decrease)
Which antibiotics penetrate the CSF regardless of inflammation?
Which antibiotics penetrate the CSF with inflammation
Which antibiotics in the CSF with or without inflammation?
What is important to know about the activity of anbiotics in CSF
pH, pharmacokinetics, etc in CSF are different
* Drugs rapidly cleared from CSF by efflux
* AMG and FQs work less well in the pH of the CSF
* CSF has impaired host defence activity
***
* Requires bactericidal agents
What are the Antibiotic administrations?
INtralumbar
Intracisternal
Intraventricular (Mostly)
What is the treatment duration for S. Pneumoniae?
10-14 days
What is the treatment duration for N. Meningitidis?
5 to 7 days
What is the treatment duration for H. Influenzae?
7-14 days
What is the treatment duration for Group B strep?
14-21 days
What is the treatment duration for Gram negative bacilli?
21 days
What is the treatment duration for Abscess?
4-6 weeks
What is the empiric antibiotic regiment for <1 month
Ampicillin + cefotaxime or ampicillin + AMG
What is the empiric antibiotic regiment for 1 month to 50yrs
Vancomycin + 3rd generation cephalosporin (cefotaxime or ceftriaxone)
What is the empiric antibiotic regimen for > 50yrs
Vancomycin + ampicillin + 3rd gen. cephalosporin
What is the emperic antibiotic regimen for Penetrating trauma or neurosurgery
Vancomycin + cefepime, vancomycin + ceftazidime, or vancomycin + meropenem
What are the antibiotics of choice for S.Pneumoniae?
- vancomycin + 3rd gen cephalosporin
- Pen G or ampicillin if pen susceptible
- Alt: meropenem, FQ
What is the antibiotics of choice for Neisseria meningitidis
- 3rd gen cephalosporin, penicillin G, ampicillin
- Alt: ampicillin, (chloramphenicol), FQ
What is the antibiotics of choice for Listeria monocytogenes
- Ampicillin or penicillin G + AMG
- TMP/SMX, meropenem
What is the antibiotics of choice for S. Agalactiae?
Ampicillin or penicillin G
Alt:3rd generation cephalosporin
What is the antibiotic of choice for Haemophilus influenzae?
3rd generation cephalosporin
Cefepime, meropenem, FQ
What is the antibiotic of choice for E. Coli
3rd generation Cehpalosoprin
Cefepime, meropenem, FQ, TMP/SMX
What is special about the AMGs?
penetrate CSF poorly, even
in the presence of inflammation
and have decreased activation
within the CSF
If you are using AMGs whenre must be be given?
- Must be given directly into CSF in
everyone except neonates - When used in combination with
penicillin (for synergy) have been
proven effective in IV form
Which generation of of cephalosporins can penetrate?
What is the supportive therapy for Meningitis?
Dexamethasone 0.15mg/kg q6h for 2-4 days
When should corticosteroids be administered?
before or within 2 hours of antimicrobials
What are the monitoring parameters for prophylaxis?
What is the Prophylaxis treatment for Meningococcal?
What is the H.Influenzae prophylaxis?
