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Year 5 Pathology Lectures > Microbiology 5 - CNS infections and meningitis > Flashcards

Microbiology 5 - CNS infections and meningitis Flashcards

1
Q

Which antibiotic should be used first line in meningitis?

A

Ceftriaxone

Add amoxicillin if they’re over 50 or immunocompromised - suspected listeria

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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 common cause of meningitis in neonates?

A

Group B strep

(Women who are colonised with Group B strep in the vagina -> abrasions to the baby during delivery -> infection)

Similar thing can occur with E. coli

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7
Q

What is the most likely causative organism in chronic meningitis?

A

TB

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8
Q

What is the most likely causative organism in aseptic meningitis?

A

Enteroviruses e.g. Coxsackie virus

Herpes is another common cause

Aseptic meningitis is the most common infection of the CNS

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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
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 (remember that the most common route of entry for CNS infection is haematogenous)

Also do a throat swab to see if they are colonised

Finally, do a blood PCR - not affected by empirical antibiotics

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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) either auramine stain or ziehl-neelsen
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

17
Q

What is the normal range for CSF protein?

A

0.15-0.4

18
Q

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

A

Purulent: turbid

Aseptic/ TB: slightly turbid or clear

19
Q

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

A

Purulent: polymorphs

Aseptic/ TB: lymphocytes

20
Q

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

A

Purulent meningitis

21
Q

Which type of meningitis produces the most protein in CSF?

A

TB meningitis

22
Q

What is the empirical therapy for meningitis?

A

Ceftriaxone 2g IV bd

Add amoxicillin if >50 or immunocompromised

23
Q

What are the 4 modes of entry for CNS infection?

A

Haematogenous spread - most common (many people’s nasopharynx are colonised with Strep pneumoniae or N. meningitidis)

Direct implantation e.g. trauma or neurosurgery complication

Local extension - secondary to established infections e.g. ear infections

PNS into CNS - viruses (e.g. rabies moving from PNS to CNS to cause encephalitis)

24
Q

What do neurotoxins affect?

A

CNS and PNS

25
Q

What class of meningitis is bacterial meningitis usually?

A

Acute meningitis (especially with Strep. pneumoniae, N. meningitidis and Haemophilus)

26
Q

Why is it important to ascertain whether it’s meningitis on its own or meningococcal septicaemia?

A

In septicaemia, there will be depletion of platelets and clotting factors -> this will affect whether you can do an LP or not

27
Q

What is the mortality and morbidity of acute meningitis?

A 
Mortality = 10%
Morbidity = 5-20%
28
Q

Who is more susceptible to listeria meningitis or encephalitis?

A

IMMUNOCOMPROMISED individuals eating blue cheese or mayo etc

CSF will contain gram positive cuboidal rods

29
Q

Which infectious cause of encephalitis can be transmitted from cats to immunocompromised individuals?

A

Toxoplasma gondii

30
Q

What is the best scan for looking at parenchymal abnormalities such as abscesses or infarctions?

A

MRI (superior to CT)

31
Q

What is the most common cause of meningitis in uncontrolled HIV?

A

Cryptococcus neoformans -> causes a high pressure meningitis

32
Q

What is the generic therapy for meningoencephalitis?

A

Acyclovir + ceftriaxone

Add amoxicillin if over 50 or immunocompromised - suspected listeria

Year 5 Pathology Lectures (87 decks)

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