Lab 001

Question 1

This test differentiates catalase-positive micrococcal and staphylococcal species from catalase-negative streptococcal species

Answer 1

Catalase test

Question 2

During catalase test, aerobic and anaerobic organisms produce two toxins during normal metabolism, these are

Answer 2

Hydrogen peroxide
Superoxide radical

Question 3

Enzyme that can convert hydrogen peroxide to water and oxygen

Answer 3

Catalase

Question 4

In catalase test, what percent of hydrogen peroxide will you add onto the medium?

Answer 4

30%

Question 5

Positive and negative catalase

Answer 5

Pos: Staphylococcus aureus
Neg: Streptococcus pyogenes

Question 6

The test used to differentiate Staphylococcus aureus and coagulase negative staphylococci

Answer 6

Coagulase test

Question 7

S. aureus produce two forms of coagulase, these are

Answer 7

Bound and free

Question 8

Coagulase also known as clumping factor

Answer 8

Bound coagulase

Question 9

It is bound to the bacterial cell wall and reacts directly with fibrinogen. This results in the precipitation of fibrinogen on the staphylococcal cells to clump when a bacterial suspenses is mixed with plasma

Answer 9

Bound coagulase

Question 10

An extracellular protein enzyme that causes the formation of a clot when S. aureus colonies are incubated with plasma

Answer 10

Free coagulase

Question 11

The clotting mechanism in coagulase test involves activation of a _________, which is a modified or derived thrombin molecule, to form a coagulase-CRF complex

Answer 11

Coagulase-reacting factor (CRF)

Question 12

Pos and neg of coagulase test

Answer 12

Pos: Staphylococcus aureus
Neg: Staphylococcus epidermidis

Question 13

These tests are routine being done in the laboratory for presumptive identification of microorganisms mostly belong to family Enterobacteriaceae and other related species

Answer 13

IMViC tests

Question 14

One of the degradation products from the metabolism of amino acid tryptophan

Answer 14

Indole

Question 15

In indole production, the the tryptophan test medium is observed by the development of a red color after adding the solution contain

Answer 15

p-dimethylaminobenzaldehyde

Question 16

Procedure of Indole test

Answer 16

1. Inoculate SIM by stabbing it halfway through the medium
2. Incubate at 35-37C for 18-24 hrs
3. Add 6 drops of Kovac’s or Ehrlich’s rgnt

Question 17

Expected results in indole test

Answer 17

Pink to wine colored ring

Question 18

Positive and negative organism of indole test

Answer 18

Pos: E. Coli
Neg: Klebsiella pneumoniae

Question 19

Indicator for methyl red test

Answer 19

Methyl red

Question 20

Bacteria that follow primarily the mixed acid fermentation route often produce sufficient acid to maintain a pH

Answer 20

Below 4.4

Question 21

Test that provides valuable characteristic in identifying bacterial ability to produce strong acids from glucose

Answer 21

Methyl red test

Question 22

Procedure of methyl red test

Answer 22

1. Inoculate bacteria in an MRVP broth for 48-72 hrs in ambient temperature
2. Add 5 drops of Methyl Red rgnt directly to the broth

Question 23

Expected results of the methyl red test

Answer 23

Positive: bright red color
Weakly positive: red-orange color
Negative: yellow color

Question 24

The test used to detect the formulation of acethyl methyl carbinol (acetoin) as a product of glucose formation

Answer 24

Voges-Proskauer Test

Question 25

It is formed as a product of an alternative pathway of glucose fermentation utilized by some species of Enterobacteriaceae

Answer 25

Acetoin

Question 26

Procedure of Voges-Proskauer test

Answer 26

1. Inoculate bacteria in an MRVP broth for 48-72 hrs in ambient temp
2. Add 6-8 drops of 5% alpha napthol, and 4 drops of 40% potassium hydroxide
3. Shake gently and leave undisturbed for 10-15 mins

Question 27

Pos and neg bacterias of Voges-Proskauer test

Answer 27

Methyl red - VP

MR (+)/VP(-): E. Coli
MR (-)/VP (+): Enteribacter aerogenes

Question 28

Expected results of the VP test

Answer 28

Pos: red color
Neg: yellow color

Question 29

This is to determine if bacterium can utilize citrate as sole source of carbon for metabolism and growth

Answer 29

Citrate Utilization Test

Question 30

Expected result of citrate utilization test

Answer 30

Pos: green to blue
Neg: green

Question 31

Pos and neg bacteria in the citrate utilization test

Answer 31

Pos: Enterobacter aerogenes
Neg: E. Coli

Question 32

LIA is useful for identification of

Answer 32

Salmonella, Proteus, Providencia, and Morganella

Question 33

They are members of Proteus group that are the only members of the Enterobacteriaceae that are deaminase positive

Answer 33

Proteus, Providencia, and Morganella

Question 34

If the organism produces lysine dearboxylase, ____ is formed

Answer 34

Cadaverine

Question 35

Neutralizes the organic acids formed by glucose fermentation, and the butt of the medium reverts to the alkaline state (purple)

Answer 35

Cadaverine

Question 36

In LIA, if oxidative deamination occurs, a compound formed, in the presence of ______ and a coenzyme, _______, forms a burgundy color on the slant

Answer 36

Ferric ammonium citrate
Flavin mononucleotide

Question 37

pH indicator of LIA

Answer 37

Bromocresol purple

Question 38

Procedure of LIA

Answer 38

1. Deep/butt is stab twice
2. Incubate at 35-37c for 24 hrs

Question 39

LIA expected results:

Lysine decarboxylation and no fermentation of glucose

Answer 39

K/K (purple/purple)

Question 40

LIA expected results:

Glucose fermentation

Answer 40

K/A (purple/yellow)

Question 41

LIA expected results:

Lysine deamination and glucose fermentation

Answer 41

Red slant/acid butt (R/A)