CNS Infections

Question 1

What are the different types of meningitis?

Answer 1

Acute/ Chronic
Bacterial/Viral
Aseptic
Fungal/Parasitic

Question 2

What is the clinical manifestation of meningitis in adults vs neonatevs elderly

Answer 2

Adults: malaise, fever, neck stiffness, photophobia, headache, convulsions

Neonate: bulging fontanelle, irritability, seizure, fever

Elderly: confusion, altered behaviour

Question 3

How is Meningitis diagnosed?

Answer 3

1) CBC : leucocytosis, WBC differential
2) ESR elevated
3) Septic Screen: sputum, urine, blood culture (positive in 60%)
4) Lumbar puncture
5) Neuroimaging

Question 4

What specimen are collected for diagnosis of meningitis ?

Answer 4

Blood and CSF

Question 5

What do you look for in CSF that is diagnostic of Meningitis?

Answer 5

Appearance
- cloudy : proteins -bacteria
- xanthochromic: yellow tinge due to Hb break down

Proteins : 15-60micg/mL
Glucose: <2/3 serum glucose
WBC: High

Question 6

List 3 main causes of Acute meningitis

Answer 6

• N. Meningitidis
• Strep. Pneumonae/ pneumococcus
• H. Influenzae

Question 7

What is the gram stain of strep pneumoniae

Answer 7

gram positive cocci in lancet pairs

Question 8

CSF with a spider clot is rare but can indicate infection with which organism ?

Answer 8

Tuberculosis

Question 9

What is the gram stain for N. Meningitidis ?

Answer 9

Gram negative cocci in bean shaped pairs

Question 10

What is the gram stain for haemophilus influenzae ?

Answer 10

Gram negative pleomorphic cocci and pus cells

Question 11

Name the organism

gram positive cocci in lancet pairs
Alpha haemolytic
catalase negative
optochin sensitive
Bile solubilty +

Answer 11

Streptococcus Pneumoniae

Question 12

Name the organism

Gram negative bean shaped diplococci
Oxidase positive
Glucose +, Maltose+, Sucrose -

Answer 12

N. Meningitidis

Question 13

Describe the colonies of N.Meningitidis

Answer 13

grey translucent

Question 14

Name the organism

Gram negative pleomorphic coccobacilli

Answer 14

Haemophilus Influenzae

Question 15

Describe how Haemophilus Influenzae is differentiate from parainfluenzae

Answer 15

H. Influenzae requires Factor V (NAD) and X to grow. Parainfluenzae only requires Factor V

Blood Agar alone : Factor X
Blood Agar cross inoculated with Staph streak : Factor X and V (NAD)
Nutrient Agar cross inoculated with Staph Streak: Factor V (NAD ) alone

Therefore; H. Influenzae and para will show satellitism in blood agar cross inoculated with staph, however only Parainfluenzae will show satelitism in the nutrient agar cross inoculated with staph

Question 16

List 5 causes of Neonatal Meningitis

Answer 16

• E. Coli
• Group B STrep (agalactia)
• Proteus miribalis
• Pseudomonas Aeruginosa
  -Listeria myocytogenes

Question 17

Name the organism

Gram positive cocci
catalase negative
Beta haemolytic
CAMP positive

Answer 17

Group B Streptococcus (Agalactiae)

Question 18

Identify the organism

Gram negative bacilli
flat dry lactose fermenters
Oxidase negative
Kligler’s (acid butt yellow+, gas)
urea and citrate -

Answer 18

E.Coli

Question 19

Idenitfy the Organism

Swarming Morphology
Gram negative bacilli
Oxidase negative
Kligler’s (acid butt yellow+, alkaline slant pink +, H2S, gas)
urea and citrate +

Answer 19

Proteus miribalis

Question 20

Identify the organism

gram negative bacilli
green pigment colonies
fruity odour
OXIDASE POSITIVE

Answer 20

Pseudomonas aeruginosa

Question 21

Name the organism

Gram POSITIVE bacilli
beta haemolytic
Catalase +
BIle ausculin +
Tumbling Motility

Answer 21

Listeria Myocytogenes

Question 22

List causative agents of Chronic Meningitis

Answer 22

• cryptococcus neoformans
• Mycobacterium Tuberculosis

Question 23

Describe the clinical manifestation of Meningitis caused by Mycobacterium Tuberculosis

Answer 23

Smothering, indolent, slow onset

Question 24

What test is used to identify Mycobacterium Tuberculosis and why?

Answer 24

Zhiel Neelson- acid fast bacilli (red against blue background)

This is because the organism has a very thick capsule that cannot be penetrated by gram stain

Question 25

What culture media can be used to isolate Mycobacterium Tuberculosis

Answer 25

Lowstein Jensen (LJ)
Middlebrook 7H10

Question 26

What stain is used to identify cryptococcus ?

Answer 26

India ink

Question 27

Identify the organism

India ink: budding yeast surrounded by halo
Gram positive oval bodies which are budding

cream to brown smooth muscle colonies

urease negative

germ tube negative

Answer 27

Cryptococcus neoformans

Question 28

What fungicide can be used to treat Cryptococcus neoformans?

Answer 28

Cycloheximide

Question 29

WHat antibiotic agents can be used to treat pseudomonas aeruginosa

Answer 29

Ceftazidime (3rd gen ceph) +
Gentamycin (Aminoglycoside)

Question 30

List organisms that can cause Brain abscess

Answer 30

• Bacteroides Fragilis
• Staphylococcus Aureus
• Streptococcus Milleri (microaerophillic)

Question 31

All obligate anaerobes like bacteroides fragilis are susceptible to which antibiotic ?

Answer 31

Metronidazole ( Nitroimidazoles)

Question 32

H. Influenzae is resistant to what group of antibiotics and by what mechanism ?

Answer 32

Betalactams- Ampicillin

This is because 30% of of the H.influenzae will produce betalactamases that will inhibit the beta lactam action of the drug Ampicillin