(Laboratory) Identification of Enterobacteriaceae Flashcards
1
Q
List down the step-by-step procedure in EMB, SSA and HEA Inoculation:
A
- Using a sterile swab, obtain a small amount of stool specimen and use it to make the first streaks in your first quadrant.
- Change into a sterilized loop and continue streaking to the second, third, and fourth quadrant.
- Incubate overnight. Observe the colonial morphology.
2
Q
List down the step-by-step procedure in the Gram Staining of Enterobacteriaceae:
A
- Prepare a smear from the bacterial source.
- Air dry and proceed with the staining.
- Observe microscopic morphology under the microscope.
3
Q
List down the step-by-step procedure in the MacConkey Inoculation:
A
- Inoculate bacteria from the source plate into the MacConkey agar.
- Incubate overnight. Observe the colonial morphology.
4
Q
List down the step-by-step procedure in TSI for Enterobacteriaceae:
A
- Sterilize your inoculating needle and pick an isolated colony from your source plate.
- Observe aseptic techniques. Stab the butt portion of the media and continue making serpentine motion on the slant portion.
- Incubate overnight. Interpret based on color reaction.
5
Q
List down the step-by-step procedure in SCA for Enterobacteriaceae:
A
- Sterilize your inoculating needle and pick an isolated colony from your source plate.
- Observe aseptic techniques. Stab the butt portion of the media and continue making serpentine motion on the slant portion.
- Incubate overnight. Interpret based on color reaction.
6
Q
List down the step-by-step procedure in SIM for Enterobacteriaceae:
A
- Sterilize your inoculating needle and pick an isolated colony from your source plate.
- Observe aseptic techniques. Stab the butt portion of the media as straight as possible. Remove the inoculating needle as straight as possible.
- Incubate overnight.
- After incubation, interpret the motility and H2S production.
- Add a few drops (3-5 drops) of Kovac’s reagent and interpret indole production.
7
Q
List down the step-by-step procedure in Methyl Red Test:
A
- Sterilize your inoculating loop and pick an isolated colony from your source plate.
- Observe aseptic techniques. Inoculate the bacteria into the broth.
- Incubate overnight
- Divide the broth into two separate tubes. Label the tube “MR.”
- In the tube labelled MR, add 5 drops of methyl red reagent.
- Observe for changes in color.
8
Q
How many drops of methyl red reagent is added in the slide for the Methyl Red Test?
A
5 drops
9
Q
What is the color of the positive result of the Methyl Red Test?
A
Red
10
Q
What is the color of the negative result of the Methyl Red Test?
A
Yellow
11
Q
List down the step-by-step procedure in Voges Proskauer Test:
A
- Sterilize your inoculating loop and pick an isolated colony from your source plate.
- Observe aseptic techniques. Inoculate the bacteria into the broth.
- Incubate overnight
- Divide the broth into two separate tubes. Label the tube “VP.”
- In the tube labelled VP, add 6 drops of alpha naphthol reagent and mix well to aerate.
- Add 2 drops of KOH reagent and mix well to aerate.
- Shake well.
12
Q
How many drops of alpha naphthol is added on the slide for Voges Proskauer Test?
A
6 Drops
13
Q
How many drops of KOH is added on the slide for Voges Proskauer Test?
A
2 Drops
14
Q
What is the color of the positive result of the Voges Proskauer Test?
A
Red Color
15
Q
What is the color of the negative result of the Voges Proskauer Test?
A
Chocolate brown
16
Q
List down the step-by-step procedure in SCA for Enterobacteriaceae:
A
- Sterilize your inoculating needle and pick an isolated colony from your source plate. Make sure to get only a small portion of the bacterial growth. Do not take too much.
- Observe aseptic techniques. Inoculate the surface of the slant with serpentine motion.
- Incubate overnight.
17
Q
Composition of TSI:
A
1% lactose
1% sucrose
0.1% glucose
18
Q
This is added to TSI tubes to detect the production of hydrogen sulfide H2S (black precipitate in the medium)
A
Ferrous sulfate
Sodium thiosulfate
19
Q
pH Indicator of TSI
A
Phenol red
20
Q
Original color of the medium of TSI
A
Red
21
Q
A similar medium to TSI but only incorporates the carbohydrates glucose and lactose.
A
Kligler’s Iron Agar (KIA)
22
Q
Both TSI and KIA or the kligler’s iron agar are poured on a slant. The slant portion is (aerobic or anaerobic) and the butt or deep portion is (aerobic or anaerobic).
A
Aerobic
Anaerobic
23
Q
In TSI, phenol red is used as the pH indicator which is yellow below the pH of _____
A
6.8
24
Q
In TSI, An inoculated medium is red, because the pH is buffered at _____
A
7.4
25
What is the TSI result if there is no fermentation that happened?
- Alkaline slant/alkaline butt (ALK/ALK or K/K) or alkaline slant/no change (ALK/no change or K/NC)
- Red/Red
26
What is the TSI result if there is glucose fermentation only but no lactose or sucrose?
- Alkaline slant/acid butt (K/A)
- Red/Yellow
27
What is the TSI result if there is lactose (or sucrose or both) fermentation?
- Acid/acid (A/A)
- Yellow/Yellow
28
What is the TSI result if there is H2S production?
- Blackening of the medium
29
What is the TSI result if there is Gas production (aerogenic) or no gas production (nonaerogenic)?
- Formation of bubbles or splitting of the medium from the bottom of the tube
30
IMViC means:
● Indole Test
● Methyl Red Test
● Voges-Proskauer Test
● Citrate Utilization Test
31
Test the ability of the bacteria to produce the enzyme tryptophanase and deaminate tryptophan to indole, pyruvic acid, and ammonia.
Indole Test
32
What media is used to test for indole?
Sulfide Indole Motility (SIM)
33
An amino acid that acts as a substrate in the Indole Test?
Tryptophan
34
Production of indole is detected using:
Ehrlich's Reagent
Kovac's Reagent
35
Positive result of Indole Test
Pink/Red Ring
36
What is the negative reaction in the Methyl Red Test?
Remain yellow after addition of MR pH indicator
37
What is the positive reaction in the Methyl Red Test?
Red color after addition of MR pH indicator
38
Media used for Methyl Red Test?
MRVP Medium
39
Reagent in Methyl Red Test
Methyl Red
40
A test that detects the production of acetoin after the addition of α-naphthol (catalyst or color intensifier) followed by 40% KOH or NaOH
Voges Proskauer Test
41
Positive reaction in the Voges Proskauer Test
Red complex
42
Catalyst or color intensifier of the Voges Proskauer Test
Alphanapthol
43
Reagent used in the Voges Proskauer Test
Alphanapthol and 40% KOH/NaOH
44
A test that determines whether an organism can use sodium citrate as a sole carbon source
Citrate Utilization Test
45
A routinely used medium in the Citrate Utilization Test
Simmon's Citrate Medium (SCA)
46
_____ are the nitrogen source in the Simmon's Citrate Medium and utilization of these results in the release of ammonia, causing a pH change
Ammonium Salts
47
pH indicator in the Cirate Utilization Test
Bromothymol Blue
48
Positive reaction in the Citrate Utilization Test
Blue
49
Negative reaction in the Citrate Utilization Test
Green
50
A test that determines whether an organism has the ability to reduce nitrate to nitrite
Nitrate Reduction Test
51
Reagent in the Nitrate Reduction Test
N,N-Dimethyl-α-naphthylamine
Sulfanilic acid
52
Positive reaction of the Nitrate Reduction Test
Red color (Diazo Red Dye)
53
Nitrate reduction test is a test that determines the production of an enzyme called _____ which results in the reduction of nitrate into nitrite.
Nitrate reductase
54
A test that determines the presence of the cytochrome oxidase system that oxidizes reduced cytochrome with molecular oxygen
Oxidase Test
55
Oxidase Test differentiates _____ which are oxidase-negative from _____ which are oxidase-positive
Enterobacteriaceae
Pseudomonas
56
Enterobacteriaceae are oxidase (positive or negative).
Oxidase negative
57
Pseudomonas are oxidase (positive or negative).
Oxidase positive
58
Reagent in the Oxidase Test
Tetramethyl-p-phenylenediamine dihydrochloride
59
Positive reaction of Oxidase Test
Purple or Lavender Color
60
An enzyme that is important in the electron transport chain
Cytochrome C Oxidase
61
A test that determines whether a microorganism can hydrolyze urea (by the action of urease enzyme), releasing a sufficient amount of ammonia to produce a color change by a pH indicator
Urease Test
62
Preferred medium for the Urease Test
Christensen’s Urea Agar
63
pH indicator for Urease Test
Phenol red
64
Positive reaction of the Urease Test
Bright pink color
65
The substrate in the Urease Test
Urea
66
Gelatin hydrolysis test is also known as the _____
Gelatin Liquefaction Test
67
Positive result of the Gelatin Hydrolysis Test
Liquefaction
68
Media demonstrate the production of H2S:
- Sulfide-indole-motility agar
- Motility-indole-ornithine agar
- Hektoen Enteric agar
- Salmonella-Shigella agar
- Triple Sugar Iron agar
- Kligler Iron agar
- Lysine Iron agar
69
SIM medium contains _____ which serves as an indicator for the production of hydrogen sulfide.
Ferrous sulfate
70
Production of hydrogen sulfide can be detected when _____, a black precipitate is produced as a result of ferrous sulfate reacting with hydrogen sulfide gas.
Ferrous sulfide
71
What is the agar concentration in the Motility Testing?
0.4% agar
72
Routine medium used in Motility Testing
Sulfide Indole Motility Agar (SIM)
73
Positive reaction of the Motility Test
Movement away the stab line or hazy appearance throughout the medium
74
Two amino acids commonly used to test for decarboxylase activity:
Lysine
Ornithine
75
Products of Decarboxylation
Amine or Diamine Molecules
CO2
76
Positive reaction for the Decarboxylase and Dihydrolase Test
Purple Color
77
Negative reaction for the Decarboxylase and Dihydrolase Test
Yellow Color
78
Reagent used in the Phenylalanine Deaminase Test
10% Ferric chloride
79
Positive reaction of the Phenylalanine Deaminase Test
Green Color
80
Species that are Phenylalanine Deaminase positive
Proteus
Morganella
Providencia
81
This is used primarily to determine whether the bacteria Decarboxylate or Deaminate lysine.
Lysine Iron Agar Slant
82
Salmonella spp. are lysine (positive or negative)
Lysine Positive
83
Citrobacter spp. are lysine (positive or negative)
Lysine Negative
84
Lysine Iron Agar Slant contains:
Amino acid lysine
Glucose
Ferric ammonium citrate
Sodium thiosulfate
85
pH indicator in the Lysine Iron Agar Slant
Bromocresol purple
86
Lysine Decarboxylation positive result
- Purple slant/purple butt (alkaline)
- K/K
87
Lysine Decarboxylation negative result
- Purple slant/yellow butt (acid), fermentation of glucose only
- K/A or R/A
88
Lysine Deamination positive result
- Red slant
- R/A
89
Lysine Deamination negative result
- Slant remains purple
- K/K or K/A
