Modules 8 & 9: Catalase, Nitrate, Coagulase, DNase, Beta-lactamase; Staphylococcus

Question 1

Beta hemolysis

Answer 1

Complete clearing of red blood cells around colony

Question 2

Alpha hemolysis

Answer 2

Partial clearing of red blood cells, greening around colony

Question 3

Gamma hemolysis

Answer 3

No clearing of red blood cells around colony

Question 4

Bacteriophage testing

Answer 4

Used to type S. aureus strains
Virus specific to bacterial strain
Bacteria lyse, plaques form

Question 5

Bound Coagulase

Answer 5

Slide Coagulase test
Differentiates S. aureus from CNS
Bound into cell wall, acts on fibrinogen to form clot

Question 6

Catalase

Answer 6

Use chocolate agar (BAP=false positive)
Reagent is H2O2
Genus test for Staph (+) and Strep (-)
Enzyme forms bubbles(O2)
Platinum wire causes false positive

Question 7

Clumping factor

Answer 7

Bound Coagulase

Detected in slide Coagulase test

Question 8

DNase

Answer 8

Depolymerizes DNA into oligonucleotides
HCl: pos=clear zone, neg=precipitate
Methyl green: pos=clear, neg=green
Toluidine blue: pos=pink, neg= blue
Virulence factor

Question 9

Exotoxin: enterotoxin

Answer 9

Preformed toxin
S. aureus food poisoning (1-6 hours)
Affects intestinal cells, lack of absorption, diarrhea, vomiting

Question 10

Facultative anaerobes

Answer 10

Can grow in AnO2 and O2 conditions, grows better in O2

Question 11

Free Coagulase

Answer 11

Determined with tube Coagulase test
Exuded into environment, not bound to cell wall
Extra cellular enzyme
SA= pos
CNS= neg

Question 12

Hemagglutination test

Answer 12

Test for S. aureus
Similar to slide Coagulase, quicker
Visible agglutination with reagent and Staph cells

Question 13

Induced beta-lactamase

Answer 13

Grow organism in presence of beta lactam antibiotic to induce expression of beta lactamase enzyme

Question 14

Staphylokinase

Answer 14

Clot buster

Allows spread into tissues

Question 15

Latex reagent

Answer 15

Test for SA

Visible agglutination with the reagent latex particle attached to SA cells

Question 16

Leucocidin

Answer 16

Chemical produced by some bacteria

Kills phagocytic white blood cells

Question 17

Micrococcus

Answer 17

Same family as Staph
Bacitracin test differentiates Staph from Micrococcus
Micrococcus=susceptible
Staph=resistant

Question 18

Nitrate test reagent A

Answer 18

Sulfanilic acid in acetic acid

Question 19

Nitrate test reagent B

Answer 19

Alpha naphthylamine in acetic acid

Question 20

Novobiocin

Answer 20

Disc test for S. saprophyticus

12mm = susceptible (other CNS)

Question 21

Oxacillin screen test

Answer 21

MRSA test
Agar dilution test with 6ug/mL oxacillin in plates
Growth = resistance (MRSA)
No growth = sensitive

Question 22

Phenol red

Answer 22

Indicator in MSA agar

Works with mannitol to differentiate SA from CNS

Question 23

Concentration of peroxide for catalase test

Answer 23

3%

Question 24

Protein A

Answer 24

Cell wall protein in S. aureus
Binds Fc portion of IgG
If present, IgG and attached latex will be bound by Staph cells = agglutination

Question 25

Pulse field gel electrophoresis

Answer 25

Cleave sections of bacterial chromosome Separate on gel and stain Provides DNA fingerprint Compare to known DNA fragments

Question 26

Catalase QC organisms

Answer 26

Pos: any Staph species Neg: stick or any Strep species

Question 27

Coagulase QC organisms

Answer 27

Pos: S. aureus Neg: S. epidermidis

Question 28

Rabbit plasma

Answer 28

Used for Coagulase test Available commercially Does not need to be screened for HIV of hepatitis Store in fridge, clear bottle

Question 29

Slide Coagulase

Answer 29

Detects bound Coagulase | Differentiates SA from CNS

Question 30

S. lugdunensis Coagulase

Answer 30

Slide +, tube -

Question 31

S. saprophyticus Coagulase

Answer 31

Slide -, tube -

Question 32

S. schleferi subspecies coagulans Coagulase

Answer 32

Slide -, tube +

Question 33

S. schleferi subspecies schleferi

Answer 33

Slide +, tube -

Question 34

Tube Coagulase

Answer 34

Detects free Coagulase | Use rabbit plasma in test tube

Question 35

Thermostable nuclease

Answer 35

Produced by S. aureus Not produced by other bacteria Test not technically suited for routine ID Useful for investigation of food poisoning

Question 36

NaCl concentration in MSA

Answer 36

7.5%