gram postiive

Question 1

what are the 2 major branches of gram positive cocci ?

Answer 1

Streptococci and Staphylococci

Question 2

how to differentiate between
Streptococci and Staphylococci

Answer 2

both gram positive cocci

but staphylococcus is in purple clusters

and streptococci is in purple chains

Question 3

name 2 of the important staphylococci

Answer 3

these are gram positive clusters

S. aureus
S. epidermis

Question 4

what is streptococci classification based on? (3)

Answer 4

Haemolysis
Lancefield typing
Biochemical properties

Question 5

what colour does beta haemolytic streptococci make the agar plate go and why?

Answer 5

full Haemolysis - produces strong enzymes which completely break down blood (complete lysis) making the agar become….

transparent

Question 6

what colour does alpha haemolytic streptococci make the agar plate go and why?

Answer 6

Partial haemolysis - goes green

this is because enzymes produced by bacteria only partially break down the RBCs on the blood agar

Question 7

what colour does gamma haemolytic streptococci make the agar plate go and why?

Answer 7

lack of haemolysis
no change observed

Question 8

what is Lancefield grouping based on?

Answer 8

bacterial carbohydrate cell surface antigens

Question 9

what strep is in lancefild group A?

Answer 9

S.pyogenes

Question 10

what are the 3 main streptococci to remember?

Answer 10

S.pyogenus

S.pneumoniae

virdans group

Question 11

S.pyogenes
- what is it?

Answer 11

= beta haemolytic type A lancfield strep (gram postive)

Question 12

S.pyogenus
- what is its virulence factors?

Answer 12

Enzymes streptokinase which breaks down clots
Erythrogenic toxin → can lead to scarlet fever

Question 13

S.pyogenes
- what infections does it cause?

Answer 13

Strep throat
Skin and soft tissue infections
Scarlet fever
A few rare Complications of strep disease

Question 14

S.pneumoniae

• when does it cause problems?

Answer 14

Hangs around in peoples throats normally but if it invades elsewhere can cause problems

invades if u r at risk eg.HIV

Question 15

S.pneumoniae

• what infections can it cause?

Answer 15

pneumonia, sinusitis,meningitis

Question 16

S.pneumoniae

• what is it?

Answer 16

alpha haemolytic strep (gram postive)

Question 17

virdans group

• which are these ?

Answer 17

alpha haemolyitc strep that are resistant to optochin test

Question 18

virdans group

• whiat infections do they cause?

Answer 18

mouth infections

deep organ abscesses

Question 19

name a member of the virdans group

Answer 19

S.oralis

Question 20

how do you identify S. aureus
from the other staphylococcus?

Answer 20

Staph. Aureus – coagulase positive

eg. s.epidermidis - coagulase negative

Question 21

Staph aureus
- how is it spread

Answer 21

aerosol and touch

Question 22

name a type of staph aureus that is very antibiotic resistant

Answer 22

MRSA

Question 23

Staph aureus
-what infections can it cause

Answer 23

pus infections eg. impetigo (pyogenic)

toxin mediated diseases eg. food poisoning

Question 24

virulence factors of S.aureus

Answer 24

Pore forming toxins
Proteases
Toxic shock syndrome toxin
Protein A

Question 25

S. epidermis and other coagulase negative staph - where do they tend to live?

Answer 25

on skin

Question 26

S. epidermis and other coagulase negative staph - when/what kind of infections do they tend to cause?

Answer 26

Don't tend to cause infection, only opportunistic eg. a big hole in the skin, Knee replacements (prostheses)

Question 27

name S.epidermis main virulence factor

Answer 27

forms biofilm

Question 28

name the 3 key gram positive aerobic bacilli (rods)

Answer 28

Corynebacterium Bacillus Listeria

Question 29

where is listeria monocytogenes found and who is advised to stay away from it?

Answer 29

opportunist, found in stinky cheese, pregnant women are advised not to eat soft cheese

Question 30

Bacillus anthracis - what can it form which makes it very easy to spread (and why is was suggested for biological warfare)

Answer 30

forms spores

Question 31

Corynebacterium diphtheriae - what does it cause

Answer 31

diptheria, upper resp infection

Question 32

name the 3 key gram positive anaerobic bacilli (rods)

Answer 32

clostridium propionibacterium

Question 33

name a type of clostridium and what disease it causes

Answer 33

C.tetani - tetanus C.botulinum - botulism C.dificile - diarrhoea