Central Nervous System Infections - Meningitis Flashcards by Alexa Carnahan

What is the dura mater?

tough outer membrane – directly adheres to skull and vertebral column

How well did you know this?

Not at all

Perfectly

What is the arachnoid?

middle layer

How well did you know this?

Not at all

Perfectly

What is the subarachnoid space?

cerebrospinal fluid
- Where infection occurs

How well did you know this?

Not at all

Perfectly

What is pia mater?

delicate innermost membrane that adheres to contours of the brain

How well did you know this?

Not at all

Perfectly

What is normal CSF levels?

WBC: <5
Differential: N/A
protein: <50
glucose: 30-70

How well did you know this?

Not at all

Perfectly

What are barriers within the CNS?

Two distinct natural barriers exist within the CNS to regulate the exchange of drugs and compounds between the blood, brain, and CSF to maintain homeostasis
Blood-Brain Barrier (BBB)
Blood-CSF Barrier (BCSFB)

How well did you know this?

Not at all

Perfectly

Drugs have to pass through what first?

BBB, which contains tightly bound endothelial cells, hard to get through

How well did you know this?

Not at all

Perfectly

What are antibiotic characteristics that influence CSF/CNS penetration?

Lipid Solubility: Lipid soluble drugs penetrate brain tissue more readily than hydrophilic drugs
Ionization: Only unionized drugs can diffuse
Protein Binding: Only free drug can penetrate
Molecular Weight: Agents with low molecular weight penetrate better
Degree of Meningeal Inflammation: Penetration of some drugs into CSF is enhanced with inflammation; decreased penetration as healing progresses

How well did you know this?

Not at all

Perfectly

What antimicrobials can penetrate CSF concentrations with or without meningeal inflammation?

Acyclovir
TMP/SMX
Voriconazole
Fluconazole
Ganciclovir
Linezolid
Metronidazole
Fluoroquinolones

How well did you know this?

Not at all

Perfectly

What antimicrobials can penetrate CSF concentrations with meningeal inflammation?

Penicillins
Some Cephalosporins (3rd
and 4th generation)
Aztreonam
Meropenem
Colistin
Vancomycin

How well did you know this?

Not at all

Perfectly

What antimicrobials can NOT penetrate CSF concentrations with or without meningeal inflammation?

Macrolides
Aminoglycosides
B-lactamase inhibitors
Some cephalosporins (1st and most 2nd generation)
Clindamycin
Tetracyclines (exception Doxycycline)
Echinocandins

How well did you know this?

Not at all

Perfectly

What is the pathogenesis of acute bacterial meningitis? - hemetogenous

Once bacteria gain access into CSF, host defenses are inadequate to contain the infection
Bacteria gain access into the CSF through:
Hematogenous spread → from the bloodstream into subarachnoid space; most
common
critical 1st step: nasopharyngeal colonization

How well did you know this?

Not at all

Perfectly

What is the pathogenesis of acute bacterial meningitis? - direct inoculation

Incidence: Uncommon compared to hematogenous
Risk factors: Neurological procedures: ventricular shunt, drains; Skull fractures; Trauma
Bacteria gain access into the CSF through:
Contiguous spread from a parameningeal focus → untreated or uncontrolled sinusitis, otitis media, or mastoiditis; Pathogens penetrate CSF while draining via CNS veins or eroding through bony structures
Direct inoculation into CSF → during head trauma or neurosurgery

How well did you know this?

Not at all

Perfectly

What is the likely causative pathogen of acute bacterial meningitis in neonates (<1mo)?

Streptococcus agalactiae
Listeria monocyogenes
Streptococcus pneumoniae
Neisseria meningitidis

How well did you know this?

Not at all

Perfectly

What is the likely causative pathogen of acute bacterial meningitis in infants (1-23mo)?

Streptococcus pneumoniae
Neisseria meningitidis
Hemophilus influenzae
Streptococcus agalactiae

How well did you know this?

Not at all

Perfectly

What is the likely causative pathogen of acute bacterial meningitis in children and adults (2-50 yr)?

Streptococcus pneumoniae
Neisseria meningitidis

How well did you know this?

Not at all

Perfectly

What is the likely causative pathogen of acute bacterial meningitis in older adults (50yrs)?

Streptococcus pneumoniae
Neisseria meningitidis
Listeria monocyogenes

How well did you know this?

Not at all

Perfectly

What are the clinical s/sx of acute bacterial meningitis?

Symptoms
Fever, chills
Headache, backache, nuchal rigidity, mental status changes
Photophobia
Nausea/vomiting, anorexia, poor feeding habits (infants)
Petechiae or purpura (N. meningitidis)

How well did you know this?

Not at all

Perfectly

What are the physical signs of acute bacterial meningitis?

Brudzinski and Kernig sign - stretching CSF or vertebral column causes pain
bulging fontanel (soft spot bulges)
meningococcal rash

How well did you know this?

Not at all

Perfectly

What is the diagnosis of acute bacterial meningitis?

Cerebrospinal fluid should be obtained: 3 tubes of CSF obtained via lumbar puncture (LP)
⎻For chemistry, hematology and microbiology testing
Elevated opening pressure (200-500mm H20) often observed due to cerebral
edema, intracranial pus, or hydrocephalus
Head CT or MRI often performed on patients presenting with papilledema, focal neurologic deficits, history of CNS disease (CVA), or impaired consciousness BEFORE LP to rule out mass lesion

How well did you know this?

Not at all

Perfectly

What is the CSF interpretation of bacterial meningitis?

WBC: >1000-5000
differential: >80% neutrophils
protein: >150
glucose: <50 mg/dL; <0.4 CSF to blood

How well did you know this?

Not at all

Perfectly

What is recommended therapy for acute bacterial meningitis in neonates?

Ampicillin + Ceftriaxone/Cefepime
Or
Ampicillin + Aminoglycoside

How well did you know this?

Not at all

Perfectly

What is recommended therapy for acute bacterial meningitis in infants?

Vancomycin + Ceftriaxone

What is recommended therapy for acute bacterial meningitis in children and adults?

Vancomycin + Ceftriaxone

What is recommended therapy for acute bacterial meningitis in older adults, immunocompromised?

Vancomycin + Ceftriaxone + Ampicillin

What is the gram stain of streptococcus spp?

Gram-positive diplococci

What is the treatment of acute bacterial meningitis - streptococcus spp?

Sensitive to penicillin: Penicillin G; Ampicillin PCN Intermediate/Resistant: Ceftriaxone Cephalosporin Resistant: Vancomycin Duration: 10-14 days

What is neurologic sequelae?

develops in pts who survive acute bacterial meningitis - seizures, sensorineural hearing loss, hydrocephalus Neuronal injury/brain damage occur as a result of activation of the host’s inflammatory pathways in response to the infection

What is the role of steroids in neurologic sequelae?

Inhibit production of IL-1 and TNF Current AAP recommendations: consider steroids in children > 2 months of age with suspected meningitis Useful in pneumococcal meningitis in adults → decrease mortality and neurologic sequelae Administer before or with 1st dose of the antibiotic Duration: 2-4 days

What is the gram stain of staphylococcus aureus?

Gram positive cocci in clusters

What is the treatment of acute bacterial meningitis - staphylococcus aureus?

MSSA: nafcillin MRSA: vancomycin duration: 14-21 days

What is the gram stain of listeria monocytogenes?

Gram-positive rod, non-spore forming

What is the treatment of acute bacterial meningitis - listeria monocytogenes?

Ampicillin +/- gentamicin Alternatives: TMP/SMX, meropenem, linezolid Duration: 21 days

What is the gram stain of neisseria meningitidis?

Gram-negative intra-cellular diplococci

What is the treatment of acute bacterial meningitis - neisseria meningitidis?

PCN MIC <0.1: pen G continuous infusion; ampicillin PCN MIC 0.1-1: ceftriaxone duration: 7 days

What is the gram stain of haemophilus influenzae?

Gram Negative coccobacillus

What is the treatment of acute bacterial meningitis - haemophilus influenzae?

Β - lactamase negative: ampicillin Β - lactamase positive: ceftriaxone duration: 7 days

What is the treatment of acute bacterial meningitis - other gram negatives?

Enterobacteriaceae (E. Coli, etc.) oCeftriaxone 2 g Q12H oCefepime 2g Q8-24H (based on renal function) oMeropenem 2g Q8-24H (based on renal function) Duration: 21 days

What are the pathogens of fungal meningitis?

Cryptococcus neoformans (predominant) Cryptococcus gattii Encapsulated soil fungus contaminated by guano

What are the risk factors of fungal meningitis?

Advanced HIV (CD4 < 200 cells/mL) Non-HIV Immunosuppression: Corticosteroid use; Organ transplant; Cirrhosis; Sarcoidosis; Lymphoma, hematologic malignancies

What is the clinical presentation of fungal meningitis?

Constitutional: Fevers, malaise Pulmonary: cough, SOB, chest pain CNS: Cognitive abnormalities, headache, neck stiffness, seizures, cranial nerve abnormalities, altered mentation, memory loss Skin: Papular lesions, vascular lesions, cellulitis Other: Virtually any organ can be involved

What is the CSF interpretation of fungal meningitis?

WBC: 10-500 differential: >50% lymphs protein: 40-150 glucose: <30-70

What are the phases of fungal meningitis treatment?

⎻Induction ⎻Consolidation ⎻Maintenance control of CSF pressure addressing immune suppression

What is the induction phase for fungal meningitis?

Ampho B: 0.7-1 mg/kg/day (infused over 24 hours) OR Liposomal ampho B 3-4 mg/kg/day PLUS Flucytosine 25 mg/kg PO QID Duration: Two weeks

What is the consolidation phase for fungal meningitis?

Non-HIV infected patient: Preferred: Fluconazole 400-800 mg PO or IV once daily Duration: 8 weeks Persons living with HIV: Preferred: Fluconazole 400-800 mg PO or IV once daily Duration: 8 weeks

What is the maintenance phase for fungal meningitis?

Preferred: Fluconazole 200 mg PO once daily Duration: Non-HIV infected patient: ⎻6-12 months Persons living with HIV: ⎻At least 12 months AND CD4 > 200 cells/mL AND suppression of viral load on ART

When should ART be initiated in HIV/AIDs patients who have cryptococcal meningitis?

5 weeks after initiation of treatment for cryptococcal meningitis ⎻ Particularly for patients whose CSF has < 5 WBC/mm3 ⎻ IRIS

What is NOT helpful in follow-up of fungal meningitis?

Serum cryptococcal antigen (CrAg)

What is viral encephalitis?

inflammatory process of the brain parenchyma in association with clinical and lab evidence of neurologic dysfunction

What pathogens are the cause of viral encephalitis?

Viremia: Enteroviruses (poliovirus); Arboviruses (West Nile virus, Colorado tick fever) Reactivation of latent virus: HSV, VZV, CMV, B-herpesvirus family

What is the clinical presentation of viral encephalitis?

Fever, headache and altered mental status (e.g., confusion, personality changes, memory impairment) Focal neurologic signs: Ataxia, aphasia, cranial nerve palsies; May also occur depending on the area of brain affected

What is the CSF interpretation of viral encephalitis?

WBC: 5-300 differential: 50% lymphs protein: 30-150 glucose: <40-70

What is the treatment for viral encephalitis?

Majority of cases are benign and self-limiting with full recovery in 7-10 days Supportive care, fluid, analgesics, antipyretics

What is the treatment for HSV encephalitis?

Adults/neonates: Acyclovir treat until HSV PCR is negative

What is the treatment for VZV encephalitis?

acyclovir alternative: ganciclovir

What is the treatment for CMV encephalitis?

ganciclovir can combine foscarnet - always combine in pts with HIV