26 - Bacterial and fungal meningitis Flashcards
Brain abscess - clinical presentation
Insidious onset of fever, headache, +/- neck stiffness
+/- altered consciousness level, seizures, focal neurological signs
Usually bacterial may be parasitic
Neisseria Meningitidis - treatment
Ceftriaxone, cefotaxime
Penicillin
Early treatment w/ intensive care
Neisseria Meningitidis - chemoprophylaxis
Close or kissing contacts
Neisseria Meningitidis - vaccination
Active against group A and C and W135
None against group B
Haemophilus influenzae - what is it?
‘Blood loving’ - unable to grow in absence of blood or certain constituents of blood.
Thought to cause influenza
Small pleomorphic gram –ve cocco-bacilli or bacilli
Haemophilus influenzae - most invasive type
B
Haemophilus influenzae - normal carriage
Restricted to humans
25-80% carry non-capsulate strains
5-10% carry capsulate strains
Throat carriage - invasion of submucosa to get to blood stream
Haemophilus influenzae - invasive infections
Meningitis
Infections
>2months -> 2 years
Haemophilus influenzae - virulence factors
Type B capsule
Fimbriae. IgA proteases, outer membrane proteins/lipopolysaccharide
Haemophilus influenzae - Treatment
Ceftriaxone, cefotaxime
Ampicillin
B-lactamase producing strains common
Chemoprophylaxis of contacts of invasive disease - rifampicin
Streptococcus pneumoniae - what is it?
Gram +ve cocci Cells in pairs Requires blood or serum for growth a-haemolytic activity on blood agar (green) Polysaccharide capsule
Streptococcus pneumoniae - where does it chill?
Human resp tract
Transmission via droplet
Streptococcus pneumoniae - what test for it?
Optochin test
Streptococcus pneumoniae - what ages?
All ages
More common and severe in elderly
In immunocompromised
Streptococcus pneumoniae - treatment
Ceftriaxone
Cefotaxime
No chemoprophylaxis of contacts of invasive disease
Streptococcus pneumoniae - steroids for meningitis in adults
50% reduction in mortality if using dexamethasone.
Given shortly or with first dose of antibiotics
Dexamethasone decreases vanco levels in the CSF, if vancomycin used, add rifampin
Steroid treatment has no benefit in meningococcal meningitis
Neonatal meningitis - what is the bacterium?
Group B beta-haemolytic Streptococci
Escheria coli
Listeria monocytogenes
Neonatal meningitis - neonatal presentation
Neonatal infection w/ variable onset
Early (5 days)
Cefotaxime
Ampicillin and gentamicin
Meningitis - complications
Death
Overwhelming sepsis
Raised intracranial pressure
Longer term problems inc. deafness, delayed development, seizure, stroke, hydrocephalus
Lymphocytic meningitis - viral meningitis
Most common meningitis w/ enteroviruses, herpes simplex
Benign outcome
Symptomatic treatment
Lymphocytic meningitis - spirochete
Treponemal
Borrelia
Lymphocytic meningitis - TB meningitis
Important differential
Insidious onset
Epidemiological risk factor for TB - needs checking
Lymphocytic meningitis - TB meningitis diagnosis
Difficult
AFB (acid-fast bacillus testing) often not seen on microscopy
Delay = worse prognosis
Lymphocytic meningitis - TB meningitis - treatment
12 months standard TB treatment
Steroids beneficial
Brain abscesses - features
Usually bacterial
Spread of organisms from adjacent structures e.g. middle ear, blood stream
Brain imaging needed
Cryptococcal meningitis - features
Cryptococcus is a yeast
Common problem in patients with late stage HIV
Insidious onset
Lymphocytic meningitis
Yeast forms seen in CSF in Indian Ink stain
Prolonged course of treatment - amphotericin, flucytosine or fluconazole
Encephalitis - features
Usually viral Involvement of brain tissue Altered conscious level In UK, herpes simplex is most common Tends to affect temporal lobes Occurs at all ages, 50% in over 50s
Encephalitis - diagnosis
Viral nucleic acid in CSF (PCR) may cause severe long term neurological problems
Encephalitis - most common virus for it
Japanese encephalitis virus An arbovirus Mainly children 1/3 die of acute illness 1/3 severe long term neurological disability 1/3 recover
Encephalitis - rabies
Common still in many countries
Dog, fox, bat bites
100% mortality
Preventable by vaccination
Clostridium tetani - what type of bacterium?
Gram +ve spore forming bacillus
Terminal round spore (drumstick)
Strict anaerobe
Clostridium tetani - spread
Soil into a wound either major or minor
Clostridium tetani - name of toxin and what it does
Tetanospasmin
Toxin genes plasmid encoded
Toxin spreads via bloodstream and retrograde transport
Binds to ganglioside receptors and blocks release of inhibitory interneurones
Convulsive contraction of voluntary muscles
Clostridium tetani - causes tetanus (clinical presentation)
Lockjaw Tonic muscle spasms Trismus Opisthotonus Resp. difficulties CV instability
Clostridium tetani - treatment
Antitoxin Penicillin or metronidazole Drugs for spasms Muscle relaxants Resp. support Prevention: toxoids
