Bacterial Meningitis Flashcards
Neurological Sequelae can develop even after proper treatment of meningitis. List these:
1) Seizures
2) Hearing Loss
3) Learning Disabilities
4) Hydrocephalus
Most common bacteria causing meningitis is:
Strep. pneumonia
List the layers of the skull:
Dura mater, arachnoid, subarachnoid space, pia mater
The three pathways bacteria can spread to cause meningitis:
1) Hematogenous spread (bacteremia, fungemia, parasites invade blood stream)
2) Neuronal pathway spread (never endings in face may transfer bacteria) (olfactory & peripheral nerves)
3) Extension from contiguous and direct inoculation (sinusitis, otitis media, trauma, intracranial manipulation)
What is meningitis?
an inflammation of the meninges affecting the subarachnoid space or spinal fluid
What is encephalitis?
inflammation of the brain tissue
Acute classification of meningitis occurs within
hours to several days
Worst classification of meningitis is…
Acute
Chronic Meningitis occurs within
weeks to months
Chronic meningitis signs and symptoms in the CSF remain abnormal for how long?
at least 4 weeks
Septic meningitis is due to…
bacteria in blood
Septic meningitis can cause what?
Altered mental status
Aseptic meningitis occurs due to
drugs/ chemical irritants, viral infections, spirochetal infections (syphillis & lyme disease)
What drugs can cause aseptic meningitis?
1) Bactrim
2) IV Ig
3) NSAIDS (Ibuprofen, Naproxen)
4) Allopurinol (gout)
What are the most likely pathogens associated with bacterial meningitis?
1) Streptococcus pneumoniae
2) Neisseria meningitis
3) H. influenza (SERO B TYPE)
Aside from the three most common bacteria, acute bact. meningitis can be caused by what other bacterias?
1) listeria monocytogenes
2) staph
3) gram negative bacilli
4) anaerobes
5) mycobacterial infxns
6) spirochetal infxns
Acute meningitis is characterized by…
an acute onset of meningeal symptoms and CSF pleocytosis (changes in CNS)
Chronic meningitis is characterized by…
signs and symptoms of meningeal irritation and CSF pleocytosis for greater than 4 weeks
Meningitis Risk Factors:
1) AGE (50)
2) Cranial or congenital deformities
3) Head trauma
4) Diabetes, hypoparathyroidism, CF, sickle cell, alcoholism, cirrhosis, IVDA, IE
5) Immunosuppression- (HIV- encapsulated Strep. pneumo) (mailgnancy- increased risk for listeria) (HIV- salmonella)
6) Crowded living conditions
7) Recent exposure to others
8) Cigarette exposure and history of ear implanatation
9) Travel- ie, meningitis belt in sub-saharan Africa
S/S are different with certain patient populations such as:
1) adults
2) infants
3) elderly
4) immunosuppresed
Classic Triad clinical presentation:
1) Headache & altered Mental Status
2) Neck stiffness
3) Fever
Clinical presentation for Adults:
1) Headache, fever, chills
2) Meningismus
3) Altered consciousness
4) seizures
5) N/V
6) Rash
7) photophobia
8) myalgia
9) sweating
Clinical presentation for Children:
1) irritability
2) temperature instability
3) lethargy, grunting, high pitched cry
4) feeding intolerance
5) N/V/D
6) seizures
7) rash
8) apnea
9) BULGING FONTANELLE (when skull isn’t fused and pressure causes swollen forehead)
Clinical presentation in Elderly:
1) Confusion
2) Mental status changes
3) Lethargic
4) Possible afebrile
5) Concurrent infections
- pneumonia
- sinusitis
- bronchitis
Most elderly present with what bacteria causing meningitis?
S. pneumoniae, BUT some may also acquire gram negative pathogens
Clinical pres of Neutropenic patients:
1) impaired immune function
2) impaired inflammation response
3) non- specific symptoms
Three signs of meningitis inflammation:
1) Kernig’s sign
2) Brudzinski’s sign
3) Jolt accentuation of headache
How do you perform the Kernig sign test?
Flex patients legs at the hip and knee, then straighten knee & report resistance or pain
How do you perform the Brudzinski sign test?
Patient supine, flex head and neck towards chest- watch for resistance and pain, and flexion of hips and knees
Jolt accentuation of headache test:
move head from right to left- document pain
What is KEY in meningitis diagnosis?
Early Identification
Diagnosis is based on what?
1) Patient history & assessment- identify causative agents
2) CT scan of head and MRI of brain
3) Clinical presentation
4) CSF results from CSF analysis & lumbar puncture
5) Blood cultures (CBC, serum electrolytes, serum glucose, BUN, CrCL, liver profile (renal fxn ))
IN ADDITION:
6) Blood, nasopharynx, resp, urine and skin cultures
7) Serum Procalcitonin (marker for inflammation)
8) Special clinical conisderations
- Acid Fast Bacilli (test for TB)
- Venereal disease research lab (VDRL)
- Fungal culture
How is CSF produced?
85% in the 3rd & 4th lateral ventricle of the choroid plexus
How much CSF is produced per day in children?
40-60 mL/ day
How much CSF is produced per day in adults?
500 mL/day
How does CSF flow?
Unilaterally- skull to spinal chord and down
You can give antibiotics to patients empirically for meningitis because:
ABX do not change the CSF for 24-48 hours so they won’t affect the initial cultures drawn
What test do you perform for collection of CSF?
Lumbar puncture (needle inserted between the 3rd and 4th lumbar vertebrae)
LP is C/I in patients with evidence of:
1) focal neurological exam
2) intracerebral pressure
3) thrombocytopenia
4) bleeding diathesis
When meningitis is suspected, what do you do first?
1) obtain two sets of blood cultures
2) immediately begin empiric ABX therapy
3) perform CT scan
Analysis of CSF:
1) appearance
2) expected cell composition
3) absence of bacteria
4) normal chem of fluid
5) normal pressure <200 mm HgO
Normal WBC & bacterial WBC in CSF
Normal: <5
Bact: 1,000- 5,000
Normal & Bacterial Differential in CSF
Normal: >90% (monocytes)
Bact: > 80 PMN
Normal & bacterial pH in CSF
Normal: 7.3
Bact: 7.1
Lactic acid in CSF
Normal: 35 mg/dL
Protein in CSF
Normal: <50
Bact: 100-500
Glucose in CSF
Normal: 30-70
Bact: <40
How many hours until mortality occurs in meningitis?
24-48 hours
Supportive care treatments are:
1) Fluids
2) Electrolytes
3) Antipyretics
4) Analgesics
5) Anti-epileptics
When you treat Men empirically, what should you do?
1) Continue ABX for 72 hours or when diagnosis of ABM is ruled out
2) Consider adjunctive corticosteroids (dexamethasone) when applicable
When pathogen is identified, how do you treat definitively?
Therapy based on specific pathogen and continue for appropriate duration.
Obstacles to consider when initially treating are?
1) Neurological morbidity even after proper treatment
2) Concerns for delay in LP or C/I
3) HIgh mortality if not treated 24-48 hours
When should you give the first dose of ABX?
ASAP - NEVER withhold if suspected
Changes in CSF after empiric ABX apparent after how many hours?
12-24 hours
What principles should you consider when recommending an ABX regimen?
1) Penetration into the CNS
- adequate drug concentration in CNS (exceed MBC > 10 fold)
- bactericidal and dependent on time in the CNS high doses and IV ONLY
2) Dependent on inflammation process
- Low MW
- Low protein binding
- Non-ionized at pH site
- High-lipid SOLUBLE
Certain ABX’s do better when there IS what in the brain?
inflammation in the brain, due to blases
MBC stands for what?
Minimum bacterioCIDAL concentration
Can you treat ABM orally?
HELL NO. IV ONLY!
What is DAT?
Direct Antimicrobial Therapy
When do you use DAT?
If MRSA is in the brain, Vancomycin cannot penetrate properly, so you need to insert a shunt in the brain or spine to administer Vanco locally. (Not preferred due to unilateral flow of CSF)
What ABX penetrate CSF with or without inflammation?
1) Sulfonamides
2) Trimethoprim
3) Chloramphenicol
4) Metronidazole
5) Rifampin
6) Pyrazinamide
7) Ethionamide
8) Cycloserine
What ABX penetrate CSF WITH inflammation?
1) Acyclovir
2) Nafcillin
3) BL/ BLI
4) FQ
5) Ceftriaxone
6) Imipenem
7) Meropenem
8) Daptomycin
9) Aztreonam
10) Linezolid
11) Synercid
12) Colistin
13) Vancomycin
What ABX are poorly entered into the CSF, but can be used empirically for hemo infxns?
1) Aminoglyc’s
2) 1st & 2nd gen Ceph’s except cefuroxime
3) Cefoperazone
4) Clindamycin
5) Erythromycin
6) Amphotericin B
7) Ketoconazole
8) Itraconazole
N. meningitis symptoms:
Asymptomatic carrier state, petechiae or purpuric lesions, rash that worsens after anti-inflamm agents used
Colonization of N. meningitis occuring in the ______________ can lead to _______________
nasopharynx, bacteremia
N. meningitis usually occurs when?
winter and spring months
What serotypes are identified with N. meningitis?
A, B, C, Y, and W-135
H. influenzae usually occurs in what population?
infants and children who are not vaccinated
What complication are common in early H. influenzae meningitis?
Neurological complications are common in early disease
What serotype is H. influenzae?
serotype B- vaccine is in the works
S. pneumo is common in what age group?
All ages
Predisposed pneumo infections leading to S. pneumoniae meningitis?
pneumonia, sinusitis, otitis media, cochlear implants
What occurs more frequently in S. pneumoniae meningitis?
Neurological compilations occur more frequently
Listeria monocytogenes meningitis is more common in what populations?
1) alcoholics
2) immunodeficient patients
3) neonates
4) elderly
Listeria meningitis normally occurs when?
summer and fall months
Listeria meningitis colonization occurs where?
GI Tract
How is listeria normally contracted?
Via food by immunocompromised patients- contaminated coleslaw, raw veggies, milk and cheese
Strep. agalactiae is common in what population?
neonates & pregnant women
A gram stain was obtained in a patient with a suspected acute case of bacterial meningitis, the results showed gram negative diplococci. What bacteria is responsible for the acute infection?
N. meningitis
A gram stain was obtained in a patient with a suspected acute case of bacterial meningitis, the results showed gram negative diplococci. What can we determine from this information?
Lumbar penetration, gram stain
Sensitivity of a gram stain % variation:
60-90%
Specificity of a gram stain is approximately what %?
100%
A patient <1 month most likely has what meningitis pathogens?
E.Coli, Strep agalactiae, Listeria, Enterococcus sp, Salmonell sp, Klebsiella
How would you treat a <1 month empirically?
Ampicillin PLUS
Ceftriaxone or
Cefotaxime (use if ceftriaxone resistance)
or an aminoglycoside
1 month- 4 years of age common pathogens?
E. Coli, Strep agalactiae, Listeria, N. Meningitis, H. influenzae,S. pneumoniae
Empiric treatment for 1 month- 4 years?
Cefotaxime or Ceftriaxone PLUS Vancomycin
5-29 yo common pathogens?
N. meningitis, H. influenzae, S. pneumo
5-29 empiric treatment?
Cefotaxime or Ceftriaxone PLUS Vancomycin
30-60 yo common pathogens?
S. pneumo, N. meningitis
30-60 yo empiric treatment?
Cefotaxime or Ceftriaxone PLUS Vancomycin
> 60 yo common pathogens?
S. pneumo, listeria, n. meningitis, Gram Neg. bacilli
> 60 yo empiric treatment?
Ampicillin PLUS Cefotaxime or Ceftriaxone or an aminoglycoside PLUS Vancomycin
CSF Shunt common bacteria?
S. epidermis, S. aureus, Gram Neg bacilli
CSF Shunt empiric treatment?
Vanco + Cefepime or Ceftazidime or Meropenem
Adjunctive therapy for men?
Empirical corticosteroid therapy
Why use corticosteroid therapy in men patients?
Inhibits TNF and IL-1
to decrease inflammation, edema, & intracranial pressure
Corticosteroids may do what to current ABX?
decrease penetration
When should you use corticosteroids in patients with men?
In children with H. influenzae meningitis
In adults with S. pneumo meningitis
When should you administer corticosteroids?
MUST admin 10-20 BEFORE or at the SAME time as ABX to prevent neuro complications
Administer corticosteroid in adults when:
suspected pneumo meningitis, increased intracranial pressure, high concentrations of bacteria in CSF, Change in mental status (Glasgow Coma Scale < II
When should you NOT admin dexamethasone?
When patient has already received ABX therapy!
Prophylaxis for patients with close contact of N. meningitis or H. influenzae?
Rifampin
