Flashcards in Infectious Diseases of the Brain Deck (59):
What is most commonly affected in bacterial meningitis?
How does bacterial meningitis spread?
Typically hematogenous spread:
-25% Otitis media, sinusitis
Causative Organisms of Bacterial Meningitis in Neonates
Group B beta-hemolytic strep and enteric gram neg bacilli
Causative Organism of Bacterial Meningitis in Children
Haemophilus influenzae (40-60%)
Most common causative organisms of bacterial meningitis in adults
N. Meningitidis (10-35%)
Other: Staphylococcus, H.Influenzae, Gram neg bacilli, Listeria)
Bacterial Meningitis causative organisms in the elderly:
Bacterial Meningitis presentation:
Fulminant illness <24 hours
Respiratory illness may precede by 7 days (25%)
What are less common presentations of bacterial meningitis?
Mental status changes.
Presentation of bacterial meningitis in infants:
High pitched crying
Refusal to eat
PE tests for bacterial meningitis:
Skin Rash - Neisseria Meningococcal (65%)
What is notable about PE for bacterial meningitis?
Poor sensitivity! Do not rely on negative exams!
How is bacterial meningitis diagnosed?
Lumbar puncture - cloudy
Other labs for bacterial meningitis:
CBC - NL does not r/o bacterial meningitis
Imaging for bacterial meningitis
CT to rule out mass or abscess
Bacterial Meningitis Treatment 1 m - 50 y
Vancomycin 1 g IV q 6 hours
Ceftriaxone 2 g IV q 12 h OR Cefotaxine 2 g IV q 6h
Bacterial Meningitis Treatment over 50
Vancomycin 1g IV q 8 h
Ceftriaxone (2 g IV q 12 h) OR Cefotaxine (2g IV q 6h)
How long do you treat Bacterial Meningitis?
S Peumoniae - 10-14 days
Neisseria - 7 days
Complications of Bacterial Meningitis
Vasculitis (arteritis- stroke; venous sinus thrombosis)
What is the prognosis for bacterial meningitis?
-meningoccemia 30% mortality rate
-meningitis alone 4-5%
Pneumococcal meningitis - 30% mortality rate
What vaccines are available for bacterial meningitis prevention?
Post exposure prophylaxis for bacterial meningitis:
Contagious 7 days prior to illness - 24 hours after antibiotics.
Rifampin x 2 days
Cipro x one oral dose
Ceftriaxone IM x1
For anyone who has been in high contact with the infected persons or healthcare workers.
Who gets the pneumococcal vaccine?
Other: asthma, smokers >50, HIV, nursing home patients
Reduces risk by 50%
Who gets the meningococcal vaccine?
Ages 11-55 yo
Before age 16 - 2 doses
Reduces risk by 50%
Viral Meningitis AKA
Incidence of Viral Meningitis
7.6 cases / 100,000 adults vs 1.5 cases/ 100,00 adults (bacterial)
Causative organisms of viral meningitis in children
Borrelia Burgdoferi (Lyme)
Causative Organisms of Viral Meningitis in adults:
Viral Meningitis Signs and Symptoms
Flue like symptoms
Can bacterial meningitis be easily differentiated from viral from an H&P?
NO!!! Must treat as bacterial until proven otherwise!! Bacterial more severe!
Treatment of Viral Meningitis
Prognosis of viral meningitis
good, very low mortality rate
Who gets Tuberculous meningitis?
How is tuberculous meningitis spread?
primary focus - lungs
Symptoms of Tuberculous meningitis?
What does a lumbar puncture show in Tuberculous meningitis?
Treatment of Tuberculous meningitis?
Pyrazinamide x 6-9 months
Who is at risk for cryptococcal meningitis?
What is encephalitis?
Inflammation of the brain
+/- meningeal involvement
Brain dysfunction predominant
Signs and Symptoms of encephalitis
Mental status changes
Most common cause of encephalitis:
Herpes Simplex Encephalitis
-HSV1 often lies dormant in the trigeminal ganglian
What symptoms does HSVI cause in encephalitis?
Presence of virus causes severe inflammation, edema, necrosis, hemorrhage.
If lymbic system is involved may cause personality changes, change in olfactory function/olfactory hallucinations.
If asymmetric involvement - may include hemiparesis and appear as stroke.
How is HSV encephalitis diagnosed?
CSF PCR for HCV GOLD STANDARD - false negatives may occur in first 12 hours and after 10 days
What will a lumbar puncture show with HSV encephalitis?
CSF leukocytes - 10-200 cells
CSF protein ~ 100 mg/dL
CSF glucose normal to low
What imaging is used for HSV Encephalitis?
MRI preferred (CT normal for first 5 days) - diffuse edema
T1 - hypointensity
T2 - hyperintensity
Treatment of HSV Encephalitis
Acyclovir IV 12.5 mg/kg IV q 8 h x 14 days
HSV Encephalitis prognosis
HIGH risk for neuro deficits
What neuro deficits can develop due to HSV encephalitis?
Memory - inability o form new memories (hippocampal destruction)
What is the leading cause of epidemic encephalitis?
When is Arbovirus prevalent?
Summer - early autumn
Incubation period for Arbovirus
2-18 days after mosquito bite
Range of arbovirus
Mild to severe
Types of Arbovirus
Eastern equine encephalitis
Western equine encephalitis
St. Louis encephalitis
West Nile Virus
What are the natural hosts of West Nile Virus (WNV)?
Animals (most commonly horses)
Humans are only incidental
Prevalence of WNV
99% of cases are asymptomatic or self-limiting
1% results in severe illness
What increases risk of severity for WNV?
Age over 50 yo increases risk of severe course 20-fold
Signs and Symptoms of NSV
+/- headache, eye pain, nausea and vomiting
PE findings for WNV
Occipital LAN (generalized LAN)
+/- maculopapular rash
Diagnosis of WNV
+/- elevated protein
- IgM ELISA (positive 8-21 days after onset)