Microbiology 1: CNS Infections And Meningitis Flashcards Preview

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Flashcards in Microbiology 1: CNS Infections And Meningitis Deck (28)
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1
Q

What is the most frequent route of entry for pathogens causing CNS infections ?

A

Haematogenous spread

2
Q

List 4 routes of entry to the CNS for pathogens

A
Haematogenous spread (meningococcus, pneumococcus)  
Direct implantation (after surgery)
Local extension (from the ear)
PNS into CNS (rabies)
3
Q

Which organism is a common cause of neonatal meningitis ?

A

Group B streptococcus

Floral bacteria in the mothers vagina

4
Q

What organism commonly causes chronic meningitis ?

A

Tuberculosis

5
Q

What organisms can cause aseptic meningitis ?

A

Enterovirus - coxsackievirus

Herpes simplex

6
Q

Which organisms cause acute meningitis ?

A

N.meningitidis
Streptococcus.pneumonia
Haemophilus.influenza

7
Q

Which N.meningitidis serotypes are there vaccinations for ?

A

B and C

8
Q

Which virus transferred by vectors including birds and mosquitoes is becoming a leading cause of encephalitis world wide ?

A

West Nile virus

9
Q

Name a bacterial cause of encephalitis ?

A

Listeria

10
Q

Which organisms can cause encephalitis via local invasion ?

A

Amoebae

11
Q

Which organism causes encephalitis via oral route ? (Eating cat poo 🤮)

A

Toxoplasmosis- e.g toxoplasma gonadii

12
Q

What are the most common organisms responsible for brain abscesses ?

A

Streptococci

Staphylococci

13
Q

What is the most common route of entry for organisms causing brain abscess ?

A

Local extension e.g from mastoiditis

14
Q

Name a common spinal infection ?

A

Pyogenic vertebral osteomyelitis

15
Q

What type of meningitis is suggested by this CSF sample ? What are the likely causative organisms ?

CSF appearance: clear
Cells: 0-5 leukocytes
Gram stain/antigen tests: negative results
Protein: 0.15-0.4 g/l
Glucose: 2.2-3.3mmol/m
A

Normal

No organisms

16
Q

What type of meningitis is suggested by this CSF sample ? What are the likely causative organisms ?

CSF appearance: Turbid
Cells: 100-2000 polymorphs
Gram stain/antigen tests: positive results
Protein: 0.5-3.0 g/l
Glucose: 0-2.2 mmol/l
A

Purulent meningitis (bacterial)

Meningococcus
Pneumococcus
Listeria

17
Q

What type of meningitis is suggested by this CSF sample ? What are the likely causative organisms ?

CSF appearance: clear/slightly turbid
Cells: 15-500 lymphocytes
Gram stain/antigen tests: negative results
Protein: 0.5-1 g/l
Glucose: 2.2-3.3 (normal)
A

Aseptic meningitis

Coxsackie virus
Echovirus
TB

Could also be:
bacterial meningitis partially treated with ABx
Encephalitis
Brain abscess

18
Q

What type of meningitis is suggested by this CSF sample ? What are the likely causative organisms ?

CSF appearance: clear/slightly turbid
Cells: 30-500 lymphocytes/ some polymorphs
Gram stain/antigen tests: negative results (scanty acid fast bacilli)
Protein: 1.0-6.0 g/l (high)
Glucose: 0-2.2 (normal)

A

Tuberculous meningitis

Mycobacterium TB

19
Q

Culture and microscopy shows a gram +ve, alpha haemolytic diplococcus organism, what is the likely organism causing the meningitis ?

A

Streptococcus. Pneumoniae

20
Q

Culture and microscopy shows a gram -ve diplococci which is non-haemolytic, what organism is the likely cause of this meningitis ?

A

Meningococcus (Neisseria meningitides)

21
Q

Culture and microscopy shows gram +ve rods, what organism is the likely cause of this meningitis ?

A

Listeria monocytogenes

22
Q

Culture and microscopy shows a positive Ziehl-Nielsen stain what organism is the likely cause of this meningitis ?

A

TB

23
Q

India ink stain: shows orbit structures (yeast cells with surrounding halos)
Lumber puncture: high opening pressure

What is the likely causative organism of this meningitis ?

A

Cryptococcus Neoformans

24
Q

Which organism commonly causes meningitis in men who have sex with men (MSM)

A

Cryptococcus Neoformans

25
Q

Which drug is effective against Meningococcus, pneumococcus, haemophilus and e.coli ?

A

Ceftriaxone I.V

26
Q

Which drug is effective at treating Listeria ?

A

Ampicillin

27
Q

Which organism is most commonly associated with recurrent aseptic meningitis (Mollaret’s meningitis) ?

A

HSV-1 and HSV-2

28
Q

Which organisms are the most common cause of aseptic meningitis ?

A

Enterovirus (80%) - Echovirus, coxsackie virus

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