Gram Negative Bacteria

Question 1

What colour do gram negative bacteria stain when the gram stain test is conducted?

Answer 1

Pink/red

Question 2

What are the three layers of the gram positive cell wall?

Answer 2

Outer membrane
Periplasmic space
Cytoplasmic mebrane

Question 3

The Neisseria species grow well in what conditions?

Answer 3

37 C
5% CO2
On chocolate agar

Question 4

What is the result of the cytochrome c oxidase test for the Neisseria species?

Answer 4

An oxidase positive test

Question 5

What infections does Neisseria meningitidis cause?

Answer 5

1. Meningitis
2. Septicemia
3. septic arthritis
4. conjunctivitis
5. endophthalmitis

Question 6

What are the 5 out of 12 subgroups of Neisseria meningitidis cause most infections

Answer 6

A
B
C
W
Y

Question 7

What test is commonly done to diagnose meningococcal meningitis

Answer 7

Spinal fluid sample
- positive test is a cloudy sample (WBC present)
- negative test is a clear sample

Question 8

What is are two common symptoms of meningococcal meningitis?

Answer 8

neck stiffness
photophobia

Question 9

Symptom of meningococcal speticaemia

Answer 9

purpuric, non blanching rash (doesnt go away when glass is pressed onto it.

Question 10

Neisseria gonorrhoeae is difficult to cultivate in the lab.. WHy?

Answer 10

• they dont have a capsule making them fragile
  -they don’t tolerate drying and must be inoculated immediately

Question 11

Which type of media is used to grow neisseria gonorrhoeae?

Answer 11

Selective media such as Modified Tahyer-Martin of MNYC as they inhibit the growth of commensal organisms

Question 12

What are the infections caused by neisseria gonorrhoeae in men, women and neonates?

Answer 12

urethritis in men
cervicitis in women (extremely negative sequelae like pelvic inflammatory disease)
ophthalmia neonatorum in neonates (eye disease)

Question 13

Infections caused by Moraxella catarrhalis

Answer 13

-otitis media
- sinusitis
-pnuemonia (in immuno compromised peeps and the eldery)

Question 14

What tests can be done to diagnose or identify Escherichia coli species?

Answer 14

See if it can ferment lactic acid (streak on macconkey agar)
indole test (positive test as a result)
MALDI-TOF

Question 15

Infections cause by Escherichia coli

Answer 15

UTI (70% of community acquired caused by e.coli)
Neonatal
wound infection
intra abdominal abscess
diarrhoea
Haemolytic uraemic syndrome

Question 16

Diseases caused by Legionella?

Answer 16

pnuemonia

Question 17

Characteristics of Vibrionaceae

Answer 17

Comma shaped, short
Actively motile
Fermenter
Oxidase positive

Question 18

What media is vibrionaceae grown on?

Answer 18

TCBS (thiosulphate, citrate bile salt sucrose) agra
alkaline peptone water

Question 19

Example of a vibrionaceae

Answer 19

V.cholera

Question 20

What conditions are used to grow H. influenzae in the lab?

Answer 20

Chocolate agar
CO2
Haemin
and NADP

Question 21

H. influenzae causes many invasive disease due to what?

Answer 21

Serotype B

Question 22

What are some examples of disease caused by H. influenza?

Answer 22

meningitis
epiglottitis
bacteriaemia
pnuemonia
septic arthritis
cellulitis

Question 23

What is needed to grow Legionella in the lab

Answer 23

Buffered charcoal yeast extract agar (BCYE) with alpha keto gluterate