gram postiive Flashcards

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1
Q

what are the 2 major branches of gram positive cocci ?

A

Streptococci and Staphylococci

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2
Q

how to differentiate between
Streptococci and Staphylococci

A

both gram positive cocci

but staphylococcus is in purple clusters

and streptococci is in purple chains

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3
Q

name 2 of the important staphylococci

A

these are gram positive clusters

S. aureus
S. epidermis

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4
Q

what is streptococci classification based on? (3)

A

Haemolysis
Lancefield typing
Biochemical properties

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5
Q

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

A

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

transparent

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6
Q

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

A

Partial haemolysis - goes green

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

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7
Q

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

A

lack of haemolysis
no change observed

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8
Q

what is Lancefield grouping based on?

A

bacterial carbohydrate cell surface antigens

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9
Q

what strep is in lancefild group A?

A

S.pyogenes

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10
Q

what are the 3 main streptococci to remember?

A

S.pyogenus

S.pneumoniae

virdans group

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11
Q

S.pyogenes
- what is it?

A

= beta haemolytic type A lancfield strep (gram postive)

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12
Q

S.pyogenus
- what is its virulence factors?

A

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

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13
Q

S.pyogenes
- what infections does it cause?

A

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

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14
Q

S.pneumoniae

  • when does it cause problems?
A

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

invades if u r at risk eg.HIV

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15
Q

S.pneumoniae

  • what infections can it cause?
A

pneumonia, sinusitis,meningitis

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16
Q

S.pneumoniae

  • what is it?
A

alpha haemolytic strep (gram postive)

17
Q

virdans group

  • which are these ?
A

alpha haemolyitc strep that are resistant to optochin test

18
Q

virdans group

  • whiat infections do they cause?
A

mouth infections

deep organ abscesses

19
Q

name a member of the virdans group

A

S.oralis

20
Q

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

A

Staph. Aureus – coagulase positive

eg. s.epidermidis - coagulase negative

21
Q

Staph aureus
- how is it spread

A

aerosol and touch

22
Q

name a type of staph aureus that is very antibiotic resistant

A

MRSA

23
Q

Staph aureus
-what infections can it cause

A

pus infections eg. impetigo (pyogenic)

toxin mediated diseases eg. food poisoning

24
Q

virulence factors of S.aureus

A

Pore forming toxins
Proteases
Toxic shock syndrome toxin
Protein A

25
Q

S. epidermis and other coagulase negative staph

  • where do they tend to live?
A

on skin

26
Q

S. epidermis and other coagulase negative staph

  • when/what kind of infections do they tend to cause?
A

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

27
Q

name S.epidermis main virulence factor

A

forms biofilm

28
Q

name the 3 key gram positive aerobic bacilli (rods)

A

Corynebacterium

Bacillus

Listeria

29
Q

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

A

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

30
Q

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

A

forms spores

31
Q

Corynebacterium diphtheriae
- what does it cause

A

diptheria, upper resp infection

32
Q

name the 3 key gram positive anaerobic bacilli (rods)

A

clostridium

propionibacterium

33
Q

name a type of clostridium and what disease it causes

A

C.tetani - tetanus

C.botulinum - botulism

C.dificile - diarrhoea