Unit 15 - CNS Infections Flashcards
What agents cause meningitis?
- Neisseria meningitidis
- Haemophilus influenzae
- Streptococcus pneumonia
Encephalitis
inflammation of the brain
Meningitis
inflammation of the meninges caused by viral or bacterial infection
What can cause encephalitis?
- HSV
- Polio
- WNV
What does the CNS include?
brain, spinal cord, cranial nerves
What is the CNS protected by?
bone and membrane layers
ex. brain - skull
ex. spinal cord - vertebral column
Blood-borne invasion across BBB to cause _____
encephalitis
Blood-borne invasion across CSF to cause ______
meningitis
How can microbes cross BBB?
1-Growing across, infecting the cells that comprise the barrier
2-Being passively transported across in intracellular vacuoles
3-Being carries across by infected white blood cells
Normal:
Cells/mL
0-5
Normal:
Protein (mg/dL)
15-45
Normal:
Glucose (mg/dL)
45-85
Septic (purulent meningits):
Cells/mL
200-20,000 (mainly neutrophils)
Septic (purulent meningits):
Protein (mg/dL)
high (>100)
Septic (purulent meningits):
Glucose (mg/dL)
<45
Septic (purulent meningits):
Causes?
bacteria, amoebae, brain abscess
Aseptic meningitis or meningoencephalitis:
Cells/mL
100-1000 (mainly mononuclear)
Aseptic meningitis or meningoencephalitis:
Protein (mg/dL)
moderately high (50-100)
Aseptic meningitis or meningoencephalitis:
Glucose (mg/dL)
Normal
Aseptic meningitis or meningoencephalitis:
Causes?
viruses, Mtb, fungi, brain abscess, partly treated bacterial meningitis
Describe bacterial meningitis
- More severe but less common
- Prior to 1990s, Hib most common
- Neisseria meningitidis, Streptococcus pneumoniae are the other two key pathogens
- Life-threatening
Neisseria meningitis:
Virulence factors
- Capsule
- IgA Protease
- Pili
- Endotoxin
- Outer membrane proteins
Haemophilus influenzae:
Virulence factors
- Capsule
- IgA Protease
- Pili
- Endotoxin
- Outer membrane proteins
Streptococcus pneumoniae:
Virulence factors
- Capsule
- IgA Protease
Possible causes of bacterial meningitis in Neonates (<1 month)
Gram negative bacilli
- E. coli, Klebsiella, Enterobacter
- Streptococcus agalactiae (group B)
- Listeria monocytogenes
Possible causes of bacterial meningitis in Infants (1-23 months)
- Streptococcus agalactiae (group B)
- E. coli
- Haemophilus influenza
- Streptococcus pneumoniae
- Neisseria meningitidis
Possible causes of bacterial meningitis in Children (>2 yrs) & Adults
- Streptococcus pneumoniae
- Neiserria meningitidis
Possible causes of bacterial meningitis in Older Adults (>65 yrs)
- Streptococcus pneumoniae
- Neisseria meningitidis
- Listeria monocytogenes
- Aerobic gram-negative bacilli
Meningococcal Meningitis:
____% of population is carrier
*Higher carrier rates during epidemics
20
Meningococcal Meningitis:
___ for attachment to epithelium of nasopharynx
pili
Meningococcal Meningitis:
Invasion of blood and meninges _____
rare
Meningococcal Meningitis:
Presence of Abs to capsular Age protects from _____
invasion
Meningococcal Meningitis:
Individuals with _____ _________ deficiency more susceptible
C5-C9 complement
Meningococcal Meningitis:
Who is at greater risk?
- Young children who have lost maternal Abs
- Adolescents who never encountered infecting serotype
Meningococcal Meningitis:
_______ infection
droplet
Droplet infection
An infection transmitted from one individual to another by droplets of moisture expelled from the upper respiratory tract through sneezing or coughing.
Droplet infection is worse during ______ and ________
overcrowding and confinement (prisons, college dorms, military barracks, etc.)
Meningococcal Meningitis:
Peak?
winter/early spring with carrier rates between 60-80%
Meningococcal Meningitis:
Incubation time?
1-3 days
Meningococcal Meningitis:
Causes sudden onset of ??? (symptoms)
- headache
- sore throat
- drowsiness
- fever
- stiff neck
- hemorrhagic skin rash (indicates septicemia)
Meningococcal Meningitis:
Mortality (untreated)
100%
Meningococcal Meningitis:
Mortality (treated)
10-15%
Meningococcal Meningitis:
Is there a vaccine available?
yes
Meningococcal Meningitis:
Which serotypes are in the vaccine?
Serotypes A, C, Y and W135 (routine childhood vaccination)
Meningococcal Meningitis:
There are two vaccines, please describe them
1) Meningococcal polysaccharide vaccine (MPSV4)
2) Meningococcal conjugate vaccine (MCv4) - 11 to 55 yr old
Meningococcal Meningitis:
Describe the lab diagnosis
- essential
- takes a gram stain of CSF
- cultures it
- counts white cell count
Haemophilus Meningitis:
What causes it?
Haemophilus influenzae B
Haemophilus Meningitis:
How many serotypes of Haemophilus influenzae B are there?
six serotypes a-f based on capsules
Haemophilus influenzae B:
Natural resident of ??
respiratory tract of infants and children
Haemophilus influenzae B:
What protects infants until 3-4 months when Abs wane
Maternal antibodies
*this provides a window of susceptibility when Abs wane
Haemophilus Meningitis:
Incubation time
5-6 days
Haemophilus Meningitis:
How fatal is it compared to meningococcal and pneumococcal meningitis?
Less fatal than both
Haemophilus Meningitis:
What can it cause?
- hearing loss
- delayed language development
- mental retardation
- seizures
Haemophilus Meningitis:
Is there a vaccine?
- Yes
- HiB vaccine
- given >2 months
Pneumococcal Meningitis:
_____ cause of meningitis
common
Pneumococcal Meningitis:
is _______
encapsulated
Pneumococcal Meningitis:
Carried in _____ of many healthy people
throats
Pneumococcal Meningitis:
Invasion of blood and meninges ____
rare
Pneumococcal Meningitis:
Low levels of capsular Abs allows for _______
susceptibility
Pneumococcal Meningitis:
Abs type _____
specific
Pneumococcal Meningitis:
_____ capsule types
> 85
Pneumococcal Meningitis:
Compare the mortality rate to Haemophilus Meningitis and Meningococcal Meningitis
Mortality rate of pneumococcal meningitis > HiB and meningococcus
Pneumococcal Meningitis:
Is there a vaccine?
Yes
Pneumococcal Meningitis:
Which vaccine is for 2-23 months and immunocompromised?
Heptavalent protein-conjugate
Pneumococcal Meningitis:
Which vaccine is for children > 5 years?
23-valent
Neisseria meningitidis:
Patients?
children and adolescents
Neisseria meningitidis:
Important clinical features?
acute onset (6-24 hr) skin rash
Neisseria meningitidis:
Mortality (% of treated cases)
7-10
Neisseria meningitidis:
Sequelae (major CNS deficit, in addition, up to 10% of patients develop deafness)
<1
Haemophilus influenzae:
Patients?
children <5 yrs
Haemophilus influenzae:
Important clinical features?
onset often less acute (1-2 days)
Haemophilus influenzae:
Mortality (% of treated cases)
5
Haemophilus influenzae:
Sequelae (major CNS deficit, in addition, up to 10% of patients develop deafness)
9
Streptococcus pneumoniae:
Patients?
all ages, especially children under 2 and elderly
Streptococcus pneumoniae:
Important clinical features?
acute onset may follow pneumoniae and or septicaemia in elderly
Streptococcus pneumoniae:
Mortality (% of treated cases)
20-30
Streptococcus pneumoniae:
Sequelae (major CNS deficit, in addition, up to 10% of patients develop deafness)
15-20
Viral Meningitis:
most ______ type
common
Viral Meningitis:
____ than bacterial meningitis
milder
Viral Meningitis:
symptoms?
headache
fever
light sensitivity (photophobia)
*milder symptoms than bacterial meningitis
Viral Meningitis:
complete recovery is _____
typical
Viral Meningitis:
Difficult to isolate virus from CSF so how is diagnosis done?
with a viral genome detection
ex. PCR
Viral Meningitis:
______ is often the cause
enteroviruses
Encephalitis
inflammation of brain parenchyma
Encephalitis:
Is it usually viral or bacterial?
viral
Encephalitis:
_______ dysfunction is typical
cerebral
Encephalitis:
What does cerebral dysfunction cause?
abnormal behaviour, seizures, nausea, vomiting, fever
Encephalitis:
What virus is the most common cause?
HSV (herpes simplex virus)
How can neonates get HSV encephalitis?
passage down birth canal of female shedding HSV-2
How can older children and adults get HSV encephalitis?
HSV-1 viral reactivation in nerves in skull (trigeminal ganglia) and the infection spreading back to temporal lobe of brain
HSV Encephalitis:
___% fatality if not treated
70
HSV Encephalitis:
Treatment?
Antiviral therapy for 21 days
Poliovirus Encephalitis:
Used to be the ______ cause of encephalitis
common
Poliovirus Encephalitis:
Symptoms?
1-4 days of fever, sore throat, malaise, followed by signs of meningitis
affect on motor neurons - can cause paralysis
Poliovirus Encephalitis:
Global efforts have _____ polio
eradicated
West nile virus:
Carried by?
- Birds and culicine mosquitoes
- Humans and horses, incidental hosts
West nile virus:
Previously in ____ and ______________
Africa
Middle East
West nile virus:
In the 1999 outbreak, how was this spread?
migrating birds
West nile virus:
How do you diagnose it?
WNV RNA detection of IgM Ab in sera/CSF
West nile virus:
Is there a vaccine?
no
West nile virus:
How do you control it?
mosquito control
West nile virus:
What suggested neurological conditions may arise from WNV?
- MS
- Parkinson’s
- Schizophrenia
- Senile dementia
Summary:
____ limits the spread of infection to CNS
BBB
Summary:
Once BBB is crossed, pathogens can cause neurologic disease by involving the meninges to cause _______ or the brain substance to cause __________.
meningitis
encephalitis
Summary:
_____ meningitis most common
Viral