Staphylococcus

Question 1

Cellular features of staphylococcus

Answer 1

1ym diameter
Gram positive cocci
Irregular arrangement
Non sporing
Non motile

Question 2

Colonial features of staphylococcus

Answer 2

Catalase positive
Resistant to dry salty conditions
2-3 mm size
Circular and smooth
Grey,white, yellow or gold

Question 3

Catalase test

Answer 3

Hydrogen peroxide + catalase enzyme = H20 + O2

Question 4

Based on cellular, colonial and catalase characteristics a … .. can be made

Answer 4

Presumptive ID

Question 5

Coagulase test methodology

Answer 5

Citrates human plasma
Suspected staph species
Incubate for 37 degrees for 30 mins

Question 6

Disadvantage of a presumptive ID

Answer 6

Cannot make a definite identification based on physical characteristics, requires further testing

Question 7

Staph genus is split…

Answer 7

By the coagulase test

Question 8

Coagulase test

Answer 8

Fibrinogen into fibrin

Question 9

Fibrin causes

Answer 9

Plasma clots

Question 10

example of Coagulase positive Staph

Answer 10

Staphylococcus aureus

Question 11

Example of Coagulase negative staph

Answer 11

Staphylococcus epidermidis

Question 12

Other than S.epidermidis, name two CNS

Answer 12

S. haemolyticus
S.saprophyticus

Question 13

S. epidermidis (about)

Answer 13

Is commensal so everyone is always colonised
spread endogenous

Question 14

S. epidermidis makes up to …

Answer 14

75% of CNS clinical samples

Question 15

s.aureus can be

Answer 15

Haemolytic

Question 16

S.aureus constantly colonises ?% of the population

Answer 16

30%

Question 17

S.aureus can be spread both

Answer 17

Endogenous and exogenous

Question 18

4 ways s.aureus can be spread

Answer 18

Hands, skin shedding, dust and clothes

Question 19

4 ways to further test what staphylococcus species is present

Answer 19

Mannitol salt agar
Staph latex agglutination
DNase
API staph test

Question 20

Virulence definition

Answer 20

the severity or harmfulness of a microorganism

Question 21

Types virulence factors of s.aureus (3)

Answer 21

Toxins
Enzymes
Cell surface proteins

Question 22

S.aureus cell surface proteins (3)

Answer 22

Protein A
Clumping factor
Fibronectin binding protein

Question 23

What are exotoxins

Answer 23

Toxins that disrupt membrane activity in host cells

Question 24

Exotoxins secreted by s.aureus

Answer 24

a,b,d,y haemolysins

Question 25

Haemolysins are

Answer 25

Pore forming toxins that create holes in cell membranes, impacting integrity causing lysis

Question 26

Protein A

Answer 26

Interferes with hormonal immune response by inhibiting phagocytosis

Question 27

Clumping factor

Answer 27

Causes plasma clotting that hides the pathogen from the immune system

Question 28

Enzymes secreted by s.aureus (4)

Answer 28

Hyaluronidase Collagenase Elastase Lipase

Question 29

Two superantigens s.aureus

Answer 29

Toxic shock syndrome toxin Staphylococcal entertoxin

Question 30

How do super antigens work?

Answer 30

Interacting with APC and T cells causing T cell proliferation and massive cytokine production

Question 31

What colour does manitol salt agar ferment s.aureus

Answer 31

Yellow

Question 32

What colour does mannitol salt agar ferment CNS

Answer 32

Pink

Question 33

Latex agglutination test CNS

Answer 33

Negative

Question 34

Latex agglutination test s.aureus

Answer 34

Positive

Question 35

DNase result s.aureus

Answer 35

Yellow ferment

Question 36

DNase result CNS

Answer 36

None