Infectious Disease Flashcards
Clinical presentation of bacterial meningitis
- Headache, stiff neck (nuchal rigidity),
- Fever
- Depressed consciousness
- Hydrocephalus from obstruction
- Inflammatory response into parenchyma → seizures
- Hyperemia → infarction of cranial nerve palsies
Diagnosis of bacterial meningitis
- Need an LP to diagnose
- evaluate CSF profile
- blood cultures + neuroimaging
- Some patients need CT/MRI before LP:
- focal neuro deficits
- decreased level of consciousness
- papilloedema
- suspected focal CNS infection (empyema, abscess)
- immunocompromised
Common organisms for bacterial meningitis < 2 mo.
- Streptococcus agalactiae (Group B) = 86%
- Gram Negative Rods = < 5%
- Listeria Monocytogenes = < 5%
- Streptococcus Pneumoniae (Pneumococcus) = 2-5%
Common organisms for bacterial meningitis 2-24 mo.
- Strep pneumo = 50%
- Neisseria Meningitides = 10-15%
- Strep Agalactiae (Group B) = 10-15%
- Hemophilus influenzae = 5-10%
Common organisms for bacterial meningitis 2-34 yrs.
- Neisseria meningitis = 40%
- Strep pneumo = 40%
- Hemophilus influenzae = 5-10%
- Strep agalactiae (Group B strep) = <5%
Common organisms for bacterial meningitis >34 yrs.
- Strep pneumo = 50-70%
- Neisseria menigitidis = 10-25%
- Hemophilus influenzae = 1-10%
- Listeria monocytogenes = 5-10%
- >25% @ > 60 yrs. or immunocompromised
CSF profile in bacterial meningitis
- WBC = 100-10,000
- cell type = PMNs
- Glucose = low
- Protein = elevated
- cultures = + for bacteria
- gram stain
CSF profile in viral meningitis
- WBCs = 10 - 2,000
- Cell type = mononuclear (lymphocyte)
- Glucose = normal
- protein = normal/slightly elevated
- cultures
- +/- for viral
- for bacteria
- PCR test useful
Management of bacterial meningitis: Neonates/Infants
- Ampicillin AND
- Cefotaxime
Management of bacterial meningitis: Children & Adults (3 mo. - 50 yrs)
- Ceftriaxone OR
- Cefotaxime AND Vancomycin
Management of bacterial meningitis: Adults > 50 yrs.
- Ceftriaxone OR Cefotaxime AND
- Vancomycin AND
- Ampicillin
Management of bacterial meningitis: Hospital acquired, recent head trauma/neurosurg, immunocomprom, alcoholics
- Vancomycin AND
- Meropenem
- +/- Ampicillin
General management guidelines for bacterial meningtitis
- start antibiotics according to age-group/infection-type
- start corticosteroids before or concurrent w/first dose of antibiotics (prevent complications)
- If LP is delayed for CT/MRI
- STAT blood cultures AND
- start empiric antibiotics
Clinical features of viral meningitis
- headache
- fever
- meningeal irritation
- milder sx than bacterial
Diagnostic tests in viral meningitis
- LP ==> CSF profile
- CSF IgM diagnostic of many aroboviruses
- PCR amplification of viral genomic material
Viral causes of meningitis
- Common
- Enteroviruses
- HSV-2
- Arboviruses (West Nile Virus - WNV)
- Intermediate/Uncommon
- HSV 1
- EBV
- VZV
- HIV
- HHV-6
CSF profile in viral encephalitis
- WBC = 10 - 2,000
- Cell type = mononuclear (lymphocyte)
- Glucose = normal
- Protein = elevated
- Culture
- +/- viral
- bacterial
- useful tests: PCR, MRI
Viral encephalitis definition
- viral infection of brain tissue (vs. only subarachnoid)
- characterized by signs/symptoms more extensive than meningitis
Clinical features of viral encephalitis
- Common: Altered consciousness, fever, and headache.
- Seizures and focal neurological signs/symptoms are common:
- personality change, alteration in mental status/level of consciousness (75-95%)
- aphasia (65-75%)
- hemiparesis (30-40%)
- ataxia (40%)
- cranial nerve palsies (30-35%)
- visual field loss (10-15%).
- Tremors, myoclonus, Parkinsonism seen in WNV.
Seasonal prevalences of viral encephalitis
- Summer/Early Fall =
- Arboviruses
- Fall/Winter =
- Lymphocytic Choriomeningitis Virus
- Winter/Spring =
- Mumps
- Any season:
- Herpes Simplex
Diagnosis of viral encephalitis
- CSF profile
- EEG abnormalities (60-90%)
- CT & MRI can help identify focal encephalitis
- PCR amplification of viral nucleic acid from CSF is the diagnostic procedure of choice for HSV, VZV, CMV, EBV, and enteroviruses.
- Detection of WNV IgM in CSF is diagnostic of WNV encephalitis and more sensitive than PCR