26 - Bacterial and fungal meningitis Flashcards by David Thomas

Brain abscess - clinical presentation

Insidious onset of fever, headache, +/- neck stiffness
+/- altered consciousness level, seizures, focal neurological signs
Usually bacterial may be parasitic

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Neisseria Meningitidis - treatment

Ceftriaxone, cefotaxime
Penicillin
Early treatment w/ intensive care

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Neisseria Meningitidis - chemoprophylaxis

Close or kissing contacts

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Neisseria Meningitidis - vaccination

Active against group A and C and W135

None against group B

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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

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Haemophilus influenzae - most invasive type

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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

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Haemophilus influenzae - invasive infections

Meningitis
Infections
>2months -> 2 years

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Haemophilus influenzae - virulence factors

Type B capsule

Fimbriae. IgA proteases, outer membrane proteins/lipopolysaccharide

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Haemophilus influenzae - Treatment

Ceftriaxone, cefotaxime
Ampicillin
B-lactamase producing strains common

Chemoprophylaxis of contacts of invasive disease - rifampicin

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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

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Streptococcus pneumoniae - where does it chill?

Human resp tract

Transmission via droplet

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Streptococcus pneumoniae - what test for it?

Optochin test

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Streptococcus pneumoniae - what ages?

All ages
More common and severe in elderly
In immunocompromised

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Streptococcus pneumoniae - treatment

Ceftriaxone
Cefotaxime
No chemoprophylaxis of contacts of invasive disease

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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 ```