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Micro Exam 3 > Brown: Clinical Aspects of Meningitis > Flashcards

Brown: Clinical Aspects of Meningitis Flashcards

1
Q

Bacterial Meningitis

Definition:

A
  • Definition: inflammation of the meninges; can have both infectious and non-infectious causes
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2
Q

Bacterial Meningitis
Epidemiology

Bacterial:
Viral:

A

Bacterial: 0.2 cases/100,000 population
• More common in adults than children
• Incidence much higher in DEVELOPING world

Viral: 10.9 cases/100,000 populations
• More common in children in adults

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3
Q

Bacterial Meningitis

Early Disease Process: (5 steps)

A
  1. Mucosal invasion
  2. Local invasion/bacteremia (may be able to make presumptive diagnosis based on blood culture)
  3. Meningeal invasion across BBB or BCB (most important step- serious 100% of the time)
  4. Bacterial replication in subarachnoid space
  5. Release of bacterial components (cell wall, lipo-oligosaccharide), which has direct effects on:
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4
Q

Bacterial Meningitis

Cerebral microvascular endothelium:

A

Cerebral microvascular endothelium

  • Increases BBB permeability
  • Results in vasogenic edema
  • Overall Result is INCREASED ICP

pg 916

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5
Q

Bacterial Meningitis

Macrophages:

A

Macrophages
-Release IL-1 and TNF
-Act on cerebral microvascular endothelium (see left) AND result in subarachnoid space inflammation
-Inflammation of subarachnoid space has 2 effects:
1. Interstitial edema: caused by increased resistance to CSF outflow
2.Cytotoxic edema: caused by host response to inflammation
Overall result is INCREASED ICP

pg 916

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6
Q

Bacterial Meningitis

Effects of Increased ICP: (2)

A

o Decreased cerebral blood flow

o Loss of cerebrovascular autoregulation

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7
Q

Bacterial Meningitis
Mucosal Colonization

Pathogenic Factors :
Host Protective Factors:

A

Pathogenic Factors:
Fimbriae
Polysaccharide capsule
IgA protease

Host Protective Factors:
Mucosal epithelium
Secretory IgA
Ciliary activity
Anti-capsular Abs
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8
Q

Bacterial Meningitis
Intravascular Survival

Pathogenic Factors :
Host Protective Factors:

A

Pathogenic Factors:
Polysaccharide capsule

Host Protective Factors:
Complement activation
Organism specific Abs

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9
Q

Bacterial Meningitis
Meningeal Invasion

Pathogenic Factors :
Host Protective Factors:

A

Pathogenic Factors:
Fimbriae
Association with monocytes

Host Protective Factors:
BBB/BCB
Note: once infection is established, this is to our disadvantage because it prevents Abx from entering

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10
Q

Bacterial Meningitis
Survival in Subarachnoid Space

Pathogenic Factors :
Host Protective Factors:

A

Pathogenic Factors:
Polysaccharide capsule

Host Protective Factors:
Poor opsonic activity of CSF
Note: Once the infection gets here, not a lot we have in the way of defense

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11
Q

Microbiology of Meningitis

<1 month: (3)

A

o Group B Streptococcus (S.agalactiae)
• Note: can decrease early onset disease by intrapartum prophylaxis of maternal carriers
o E.coli
o Listeria monocytogenes

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12
Q

Microbiology of Meningitis

1-23 months: (5)

A 
o	Group B Strep
o	E.coli
o	Streptococcus pneumoniae
o	Haemophilus influenza (may see it before vaccine series is complete)
o	Neisseria meningitidis
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13
Q

Microbiology of Meningitis

24 months to 18 years: (3)

A

o Neisseria meningitidis (most common)
o S.pneumoniae
o H.influenzae (only if unvaccinated or immunocompromised for some reason)

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14
Q

Microbiology of Meningitis

18-50 years: (2)

A

o S.pneumoniae (most common)

o N.meningitidis

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15
Q

Microbiology of Meningitis

≥50 years: (4)

A

o S.pneumoniae
o N.meningitidis
o L.monocytogenes (considered in immunocompromise or pregnancy)
o Aerobic gram negative bacilli (E.coli, Klebsiella)

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16
Q

Microbiology of Meningitis

Head trauma/post neurosurgery: (3)

A

o Staphylococcus aureus
o Staphylococcus epidermidis
o Aerobic gram negative bacilli (including Pseudomonas)

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17
Q

Microbiology of Meningitis
Basilar skull fracture/CSF leak
Pt notices:
Microbes: (3)

A

Basilar skull fracture/CSF leak: head trauma occurs, and during recover patient notices clear drainage out of nose (can be tested for glucose to diagnose as CSF leak); may also be less noticeable (ie. no leakage), and should always be considered in cases of recurrent bacterial meningitis
o S.pneumoniae
o H.influenzae
o Group A, B-hemolytic streptococci

18
Q

Bacterial Meningitis

Symptoms: (6)

A

o Headache (due to increased ICP)
o Fever (systemic response to infection- not meningitis specific)
o Neck stiffness (due to inflammation of meninges)
o Photophobia (due to inflammation of meninges)
o N/V (due to increased ICP)
o Change in mental status (generally depressed status)

19
Q

Bacterial Meningitis
Clinical Findings
Adults: (5)

A

o Adults: from most common to least common

  • Neck stiffness (nuchal ridgidity)
  • Fever
  • Mental status change
  • Focal neurological finding (often due to cerebral vasculitis and infarction)
  • Rash (petechial rash seen classically with N.meningitidis, but can be seen with others)
20
Q

Bacterial Meningitis
Clinical Findings
Children:

A

o Children:

  • Older Children: similar to adults
  • Neonates/Infants/Non-Verbal Children: much more subtle presentation
  • Fever
  • Irritability
  • Poor-feeding
  • Bulging fontanel (occurs late in infection; want to diagnose before this occurs)
21
Q

Bacterial Meningitis
Underlying conditions that can predispose to the development of bacterial meningitis

Acute/chronic otitis media/mastoiditis:
Sinusitis:
Pneumonia:

A

Acute/chronic otitis media/mastoiditis (S.pneumo)
Sinusitis (S.pneumo)
Pneumonia (S.pneumo)

22
Q

Bacterial Meningitis
Underlying conditions that can predispose to the development of bacterial meningitis

Endocarditis:
Recent/remote head trauma:

A 
o	Endocarditis (continuous bacteremia)
o	Recent/remote head trauma (CSF leak)
23
Q

Bacterial Meningitis
Underlying conditions that can predispose to the development of bacterial meningitis

Immunsuppression:
Alcoholism:

A

Immunsuppression

  • Particularly humoral immunity defects or splenic dysfunction (encapsulated organisms)
  • Deficiency of terminal components of complement

Alcoholism (suppresses the immune system); at risk for Gram negative meningitis- E.coli, Klebsiella)

24
Q

Bacterial meningitis is a medical emergency: need to move quickly; the diagnosis is made by:

Can also diagnose with:

A

lumbar puncture

Blood cultures

25
Q

Bacterial meningitis
CSF parameters that need to be evaluated

Normal pressure:
Glucose with simultaneous:

A

o Opening pressure (normal is 20 cm)
o Cell count (RBCs, WBCs, differential)
o Protein
o Glucose (with simultaneous serum glucose)

26
Q

Bacterial meningitis
CSF parameters that need to be evaluated

Best Bacterial Ag detection:
Often just do:
Gram stain sensitivity is lower for:
Better for:

A

o Bacterial Ag detection (latex agglutination is best, but sensitivity varies); often just do a Gram stain!
o Gram stain and culture (sensitivity lower for Gram negative bacilli and L.monocytogenes; better for S.pneumo, N.meningitidis, H.influenzae)

27
Q

CSF parameters that need to be evaluated

In some cases (when rarer causes are suspected):

A
  • VDRL (neurosyphilis?)
  • Cryptococcal Ag (AIDS)
  • Acid fast bacilli stain and culture (Mycobacterium)
  • Fungal stain and culture
  • Cytology
28
Q

Bacterial meningitis
Management

Antibiotics:
Corticosteroids:

A

Antibiotics: must be chosen based on spectrum of causative agents and CSF penetration (cetriaxone is the go to)

Corticosteroids: anti-inflammatory (shown to be beneficial in adults with bacterial meningitis in the developed world; controversial in pediatric patients)

29
Q

Supportive care with management of complications

Early

A

Septic shock
DIC
Respiratory failure (ARDS)
Cerebral edema

30
Q

Supportive care with management of complications

Late (After Recovery)

A

Behavioral/learning disabilities (children)
Hearing loss (especially GBS infection in adults)
Seizures
Hydrocephalus

31
Q

Overall mortality for CA-meningitis:

A

25%

32
Q

Pathogen specific mortality: from highest to lowest (6)

A 
o	L.monocytogenes (28.5%)
o	S.pneumoniae (19-26%)
o	GBS (7-27%)
o	N.meningitidis (10%)
o	H.influenzae (6%)
33
Q

Bacterial meningitis

Risk factors for mortality:

A

o Age >60
o Obtunded mental status (depressed mental capacity)
o Seizures within first 24 hours of admission
o Otitis/sinusitis
o Absence of rash
o Bacteremia
o Thrombocytopenia
o Low CSF WBC count (because that means the host immune response isn’t what it should be)

34
Q

Bacterial meningitis

Prevention:

A

o Antibiotic prophylaxis for close contacts
o Meningococcal vaccine (however, does not cover serotype B)
o HIB conjugate vaccine
o 23 or 13-valent pneumococcal conjugate vaccine
o Management of GBS colonization during pregnancy

35
Q

Aseptic Meningitis
Lymphocyte predominant pleocytosis with:
Most common cause is:

A
  • Lymphocyte predominant pleocytosis with negative bacterial stains/cultures
  • Most common cause is enteroviruses
36
Q

Aseptic Meningitis
Most common in:
Presentation similar to:
Disease occurs commonly when?

A

o Most common in infants and young kids, but may also occur in adults
o Presentation similar to bacterial meningitis but LESS SEVERE
o Disease occurs commonly in late summer and early fall (often associated with community epidemics)

37
Q

Bacterial

Protein:
Glucose:
WBC:
% PMNs:

A

Increase (>100mg/dl)
Decrease (1000 cells/mm3)
Majority are PMNs
>50%

38
Q

Aseptic

Protein:
Glucose:
WBC:
% PMNs:

A

Normal or slight increase
Generally normal
Less of an Increase (50% PMNs in viral meningitis if LP is done very early in the course of disease

39
Q

NORMAL neonates may have
WBC/mm3:
protein levels:

A

NORMAL neonates may have up to 30 WBC/mm3 and protein levels up to 150mg/dl in their CSF

40
Q

Differential diagnosis of the aseptic meningitis syndrome:

IMPORTANT:

A

• Differential diagnosis of the aseptic meningitis syndrome:

- IMPORTANT: not exclusively caused by infections

41
Q

Aseptic Meningitis

Other causes:

A

o Carcinomatous meningitis
o Autoimmune diseases (lupus, RA, Kawasaki’s disease etc.)
o Drugs (NSAIDs, TMP/SMX, IVIG, carbamazepine, etc.)

Micro Exam 3 (11 decks)

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