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MICRO ADYA > Microbiology 5 - CNS infections and meningitis > Flashcards

Microbiology 5 - CNS infections and meningitis Flashcards

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1
Q

Which antibiotic should be used first line in meningitis?

A

Ceftriaxone

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2
Q

Is listeria meningitis is suspected, what antibiotic therapy should be used?

A

Ceftriaxone plus amoxicillin

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3
Q

Which pathogen is most likely to be the cause in myelitis?

A

Poliovirus

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4
Q

What is myelitis?

A

Inflammation of the spinal cord

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5
Q

Recall the 3 most likely causative organisms in acute meningitis, and the most susceptible demographic of patient to each

A

N. meningitidis = young
S. pneumoniae = elderly (so vaccine at 65 years)
H. influenzae = those who haven’t had HiB vaccine

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6
Q

What is the most commonn cause of meningitis in neonates?

A

Group B strep

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7
Q

What is the most likely causative organism in chronic meningitis?

A

TB

(or cryptococcus according to path guide)

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8
Q

What is the most likely causative organism in aseptic meningitis?

A

Coxsackie virus

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9
Q

Describe the rash produced by meningococcal meningitis

A

Non-blanching purpuric rash

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10
Q

What is the most likely viral cause of encephalitis in the UK and worldwide?

A

UK: HSV 1
Worldwide: WNV

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11
Q

Recall 3 possible routes of infection that may cause a brain abscess

A

Direct expansion from

  • otitis media
  • mastoiditis
  • paranasal sinusitis
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12
Q

What is the most common type of spinal vertebral infection?

A

Pyogenic vertebral osteomyelitis

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13
Q

What is the most common cause of pyogenic vertebral osteomyelitis?

A

Infective endocarditis - staph/ strep can be ‘flicked off’ the valve

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14
Q

What is the first investigation to do in suspected meningitis?

A

Blood cultures

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15
Q

Recall the stains used in CSF analysis to look for a) bacteria b) TB and c) fungi

A

a) gram stain
b) auramine stain
c) India ink

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16
Q

If “alpha haemolytic diplococci” are found in CSF, what is the pathogen causing meningitis?

A

Streptococcus pneumoniae

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17
Q

What is the normal range for CSF protein?

A

0.15-0.4

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18
Q

What is the appearance of CSF in purulent vs aseptic vs TB meningitis?

A

Purulent: turbid
Aseptic/ TB: slightly turbid or clear

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19
Q

What type of cell is elevated in the CSF in purulent vs aseptic vs TB meningitis?

A

Purulent: polymorphs
Aseptic/ TB: lymphocytes

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20
Q

In which type of meningitis will gram stain antigen tests be positive?

A

Purulent meningitis

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21
Q

Which type of meningitis produces the most protein in CSF?

A

TB meningitis

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22
Q

What is the empirical therapy for meningitis?

A

Ceftriaxone 2g IV bd
Add amoxicillin if >50 or immunocompromised

ALSO GIVE STEROIDS (DEXAMETHASONE) (as long as >1 month old and NOT MENINCOCCOCAL)

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23
Q

What are the routes of infection into the CNS and which is the most common?

A

Haematogenous spread (e.g. pneumococcus, meningococcus, herpes)

Direct implantation (e.g. trauma)

Local extension (e.g. from the ear)

PNS to CNS (e.g. rabies)

*haematogenous is the most common

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24
Q

Which organisms cause aspetic meningitis?

A

Herpes

Enteroviruses

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25
3 big causes of acute meningitis
Neisseria Haemophilus Strep Pneumoniea
26
Incidence of rash with N. Meningitidis
A nonblanching rash develops in 80% of children A maculopapular rash remain in 13% of children and no rash in 7%
27
How quickly do you need to give antibiotics for N. Meningitidis infection?
Within 1 hour
28
N Meningiidtis Gram stain
Gram negative, non haemolytic, cofffee bean shaped diplococcus
29
Age distribution of Strep Pneumoniea
Bimodal a) children/young people b) elderly
30
S. Pneumoniea LP gram stain and blood agar plate
Gram positive diplococci with some erythrocytes Blood agar plate: partial alpha haemolysis
31
Listeria gram stain
Gram positive rods
32
What organism commonly causes meningoencephalitis?
Listeria monocytogenes
33
Which age groups does E. Coli meningitis affect?
Bimodal age distribution a) neonates b) elderly/immunocompromised - from UTIs
34
Which organisms cause meningitis in neonates?
Group B Strep E Coli Listeria (GEL)
35
Why is LP contraindicated in meningococcal septicaemia?
Coagulopathy can lead to paresis from LP site downwards
36
Which organisms cause chronic meningitis?
TB Cryptococcus- only seen in HIV Spirochetes
37
Which group of patients does TB meningitis affect?
Mainly immunocompromised
38
TB: LP gram stain and MRI findings
**LP gram stain:** show up using Ziehl Neilson stain - cuboidal structures that appear red against blue stain **MRI:** leptomeningeal enhancement
39
Complications of TB meningitis
Abscesses Granulomas Cerebreitis (i.e. inflammation of the cerebrum itself)
40
Cryptococcus meningitis - LP findings - gram stain and opening pressure
**LP findings:** using INDIAN INK STAIN- appears like an orbit. Yeast in the middle with a capsule around the outside Opening pressure - HIGH
41
Tx of cryptococcal meningtis
Amphoterecin
42
Which is the most common infection of the CNS?
Aseptic meningitis - i.e. viral
43
Which organisms commonly cause aseptic meningitis?
Enterovirus: Cocksackie B and echoviruses HSV 1 and 2
44
WHich age group does aseptic meningitis tend to affect?
Young children \<1 year
45
How do you manage aseptic meningitis?
It is acute and self limiting. resolves within a few weeks Give supportive treatment like analgesia, anti-emetics etc.
46
Most common causative organism of encephalitis in the UK
Herpes Simplex Virus
47
Another viral cause of encephalitis that is becoming more common internationally
West Nile Virus- becoming leading cause internationally Spreading west towards UK
48
Bacterial causes of encephalitis
Listeria monocytogenes
49
Parasitic causes of encephalitis
Toxoplasmosis ## Footnote An obligate intracellular protozoal parasite, Toxoplasma gondii Via the oral, transplacental route or organ transplantation Causes severe infection in immunocompromised patients
50
AMoebic causes of encephalitis
Naegleria fowleri Habitat- warm water Acanthamoeba species, and Balamuthia mandrillaris ^can cause brain abscesses, aseptic or chornic meningitis
51
What differentiates meningitis and encephalitis?
The disturbance of cognitive function (ENCEPHAITIS) is what differentiates meningitis to encephalitis
52
Difference between management of herpes meningitis and herpes encephalitis:
Herpes meningitis does NOT need therapy BUT herpes encephalitis is a MEDICAL EMERGENCY
53
2 causative organisms of brain abscesses
* Streptococci (both aerobic and anaerobic) * Staphylococci * Others: * Gram-negative organisms (particularly in neonates) * Mycobacterium tuberculosis * Fungi * Parasites * Actinomyces and Nocardia species
54
Cerebral abscess: MRI finding
Ring enhancing lesion
55
Which routes of bacterial entry enable spread to become brain abscess?
1. Direct extension: from otitis media or sinusitis or mastoiditis 2. Haematogenous- especially from endocarditis, caused by Staph and Strep
56
Why are brain abscesses dangerous?
They cause death through compression of structures
57
Osteomyelitis vs myelits
Osteomyelitis: Inflaqmmation of the vertebrae Myelitis: inflammation of the spinal cord
58
Osteomyelitis: common organisms, route of entry, age distribution,
a) most common organism: Staph auerus b) routes of spread: 1) Derives from central site of infection: e. g. endocarditis flicking off emboli 2) Direct open spinal trauma: from infections in adjacent structures 3) Haematogenous spread of bacteria:particularly from S. pneumoniae to a vertebra c) risk factors * Advanced age * Can occur in pregnant women * IVDU * Long-term systemic steroids * Diabetes mellitus * Organ transplantation * Malnutrition * Cancer * LPs can also cause this
59
What organism commonly causes myelitis?
Poliovirus
60
CSF results table
61
CT vs MRI for detecting neurological lesions
MRI is better for parenchymal detection but CT is obviously cheaper
62
Generic therapy for meningitis
IV ceftriaxone If \>50 or immunocompromised- add amoxicillin
63
Generic therapy for meningo-encephalitis
IV ceftriaxone + IV aciclovir Add amoxicillin if \>50 or immunocompromised
64
When do you isolate patients with meningitis? And what do you give to contacts?
Isolate only if menigococcal- not if aseptic Need to give ciprofloxacin to contacts
65
Summary table of specific therapy for meningitis
66
What type of organism is Haemophilus influenzae
Gram negative Non-spore forming Cocobacillary rods Encapsulated Immotile
67
68
Where can brain abscess spread from?
Otitis media haematogenous spread
69
Normal blood csf glucose
2.2-2.3 (60% of blood level)

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