CNS Infections Flashcards
What are the 3 CNS infections?
meningitis
encephalitis
brain abscess
What are the features of neisseria meningitidis histologically?
gram negative diplococci
requires blood for growth - chocolate agar
13 capsular types
can also be detected by nucleic acid amplification
Where is the natural habitat of neisseria meningitidis?
nasopharynx
In what circumstances does the amount of neisseria meningitidis in the nasopharynx increase?
smokers
outbreak communities
Gp A carriage rates before epidemic
university students in 1st term
What diseases can neisseria meningitidis cause?
fulminant septicaemia septicaemia with purpuric rash septicaemia with meningitis pyogenic meningitis with no rash focal sepsis conjuctivitis endophthalmitis chronic meningococcal bacteraemia with arthraligia
When does blanching occur in meningitis?
Early in disease
therefore non blanching is not diagnostic
What is the treatment for neisseria meningitidis?
ceftriaxone
cefotaximine
penicillin
Who receives chemoprophylaxis and what is the chemoprophylaxis for neisseria meningitidis?
close of kissing contact
rifampicin
ciprofloxacin
vaccine against group A, C and W135
What is haemophilus influenza?
not an influenza
causes respiratory symptoms
only grows in blood
What is haemophilus influenza histologically?
small pleomorphic gram -ve bacilli some strains have polysaccharide capsules
Which type of haemophilus influenza causes the most invasive disease?
Type B
What is the treatment for haemophilus influenza?
Ceftriaxone
Cefotaxime
What chemoprophylaxis is given to those in contact with a person with haemophilus influenza?
Rifampicin
Type B vaccine
What is streptococcus pneumoniae histologically?
gram +ve cocci
cells in pairs
blood/serum for growth
polysaccharide capsule
What is the normal habitat of streptococcus pneumoniae?
human respiratory tract - transmission via droplet spread
What is optochin/ethyldydrocupreine?
lab only antibiotic - strep pneumonia is the only strep sensitive to it
What age group does streptococcus pneumoniae affect?
all ages
more common and severe in elderly
more common in immunocompromised
What is the treatment for streptococcus pneumoniae?
ceftriaxone
cefotaxime
steroids e.g. dexamethasome
What micro-organisms cause neonatal meningtitis?
group B β haemolytic streptococci
escherichia coli
listeria monocytogenes
How is neonatal meningitis acquired?
bugs from the birth canal which come from the GI tract get transferred to the baby
What is the treatment for neonatal meningitis?
ampicillin
gentamicin
What is cryptococcal meningitis?
yeast
common in immunocompromised/late stage HIV
lymphocytic meningitis
capsular organism
How is cryptococcal meningitis seen in CSF? which stain is used?
indian ink stain
What is the treatment for cryptococcal meningitis?
prolonged treatment
amphotericin
fluctosine
fluconazole - normally for life
What is clostridium tetani histologically?
gram +ve spore forming bacillus
strict anarobe
terminal round spore
Where does clostridium tetani live?
soil - transmission by contamintated soil in a wound
What is the toxin that clostridium tetani produces how does it cause symptoms?
toxin = tetanospasmin
toxin genes plasmid encoded
toxin spreads via bloodstream and retrograde transport (towards axon)
binds to ganglioside receptors
blocks release of inhibitory interneurons
convulsive contraction of involuntary muscles
What are the symptoms of clostridium tetani?
‘lockjaw’
tonic muscle spasms
trismus - spasm of jaw muscles, causing the mouth to remain tightly closed
Opisthotonus - state of severe hyperextension and spasticity in which an individual’s head, neck and spinal column enter into a complete “arching” position
respiratory/cardiovascular dificulties
What is the treatment for clostridium tetani?
Antitoxin
penicillin/metronidazole
muscle relaxants
respiratory support
What is used as prevention for clostridium tetani?
toxoid - antibodies against toxins
