L11 - CNS finections Flashcards
What infections may occur in the brain?
meningitis
encephalitis
brain abscess
What is meningitis?
infection of membranes surrounding the brain
What 3 bacteria case >80% of bact meningitis?
H. influenzae
N. meningitidis
S. pneumoniae
What is worse - viral or bacterial meningitis
bacterial
viral - self-limiting infection - complete recovery normally
What are causes of neonatal meningitis?
Group B Strep
L. monocytogenes
Enterobacteriaceae
Fatcs about S. pneumoniae meningitis?
gram-pos diplococcus
encapsulated
most COMMON cause of bacterial meningitis
occurs at any age
20-30% mortality
Facts about N. menigitidis pneumonia?
gram-neg diplococcus
capnophilic
CAPSULE required for infection
most common in childred/young adults
skin symptoms of N. meningitidis meningitis?
non-blanching rash
What does the capsule prevent from?
opsonisation and complement-mediated lysis
How does S.pneuomoniae bind and invade?
Ply overreacts the complement system
Adhesins PspA
PAFR - mediated uptake
How does N. meningitidis bind and invade?
Type IV pilli
Cortical plaque production - open inter-endothelial junctions
Facts about H. influenzae meningitis?
Gram-neg pleomorphic
capsule
How are infants protected from H. influenzae?
mother’s antibodies, then they are vaccinated
not protected in between vaccinnation
What is M. tuberculosis meningitis?
‘chronic’
difficult to diagnose = delay treatment
can’t gram stain, grows slowly in culture
What are symptoms of meningitis?
fever
severe headache
Kernig’s sign (stiff neck)
Photophobia
What is examined in the lab to detect meningitis?
CSF
What can be done in the lab to diagnose meningitis?
macroscopic - blood (should NOT be in CSF)
microscopy - cell count, Gram/India ink stain
culture
Biochemistry
Molecular based detection
How is real-time PCR used to identify causative agents of meningitis?
TaqMan probes
flourescence occurs when polymerase cleaves the probe, releasing the fluorophore and quencher
What chemotherapy is used for menigits?
SO many
look at slides
What is a brain abscess?
suppurative pus-filled lesions in brain parenchyma
What are symptoms of a brain abscess?
fever
headache
seizures
What bacteria cause brain abscess?
POLYMICROBIAL
Strep
S.aureus
Bacteroides
Gram-neg enteric
How is a brain abscess diagnosed?
CT scan
NO lumbar puncture - OTHERWISE coning can occur - brain ‘sucked’ down spine
What is a subdural empyema?
infection between outer 2 meningeal layers
POLYMICROBIAL
What are the symptoms of subdural empyema?
fever confusion headache seizure coma
What is a ventricular shunt infection?
shunt release high inter-cranial pressure causes in hydrocephalus
biofilm infection by CoNS
How can a ventricular shunt infection occur?
surgical approach
seeding of organisms in the blood
