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2) Introductory Microbiology COPY > Lab 4-7 > Flashcards

Lab 4-7 Flashcards

1
Q

what is permissive for growth ion the MacConkey agar? What is a + test?

A

Gram negative enetrobacteria (in intestine) can grow despite the bile salts and will be able to FERMENT lactose, turning the agar pink

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2
Q

MacConkey agar has a yellow colour - what does this mean?

A

A non-enteric bacteria is present (gram +) and lactose was not fermented.

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3
Q

What is permissive for growth on the Mannitol-salt agar? Describe a + test.

A

Halophiles or halotolerant, such as staph, aureus. Resistant to NaCl and are characterized by lowering the OH and proaction of yellow colour, since hey are capable of FERMENTING the mannitol.

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4
Q

The Mannitol-salt agar has a pink colour - what happened?

A

Mico present was not a halophile, and could not tolerate the NaCl salts, could not ferment the mannitol and plate is pink coloured.

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5
Q

How is the Starch Agar (SA) plate prepped? How can we detect if the starch becomes hydrolyzed?

A

Flood SA plate with iodine

A simple sugar will become hydrolyzed, indicated by a CLEAR zone due to production of amylase enzyme.

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6
Q

How do we know if starch remains unhydrolyzed?

A

Unhydrolyzed starch will stain a deep blue

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7
Q

How can we detect if the Milk Agar, containing casein becomes degraded?

A

If the micro possessed an extracellular enzyme, a clear zone around the bacterial growth of the MA will appear.

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8
Q

During the carbohydrate fermentation test (with tubes) whats were the 3 medias?

A

Glucose, Lactose, Sucrose

the sole source of carbon

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9
Q

What was added to the 3 medias?

A

each had a pH indicator (phenol red) and an inverted durham tube to trap any gas produced.

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10
Q

In the carbohydrate fermentation test, presence of yellow colour and gas indicated that …

A

E.coli or B.subtilis was able to undergo fermentation of the sugar

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11
Q

The Peptone Iron agar was used in which test?

A

Hydrogen sulfide production

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12
Q

What amino acid is found in the peptone iron agar? What can organisms degrade this into? What is a + test?

A
  • Contains CYSTEINE
  • Degrade into H2S (gas) and ferrous sulfide (black precipitate)
  • Presence of glass + black solution = + test
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13
Q

Which organisms where inoculated in the petone iron tube?

A

P. vulgaris and E.coli

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14
Q

What is a nitrate reducer?

A

Reduced NITRATE (No3-) to NITRITE (No2-)

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15
Q

What is a denitrifier?

A 
Reduced NITRATE (No3-) to NO, N20, or N2
(Reduced the nitrate further)
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16
Q

In the nitrate reduction and denitrification test, what was the sole source of nitrogen?

A

Nitrate (No3-) Salt

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17
Q

What was inoculated in the nitrate broth?

A

B. Subtitles
S. marcescens
P. aerogonisa

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18
Q

After addition of Nitrate reagent 1 and 2, the nitrate broth turns RED, what happened?

A

Presence of a nitrogen REDUCER (No3–>No2-)

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19
Q

After addition of nitrate reagent 1,2 and ZINC, the nitrate broth turned RED, what happened? How can the colour change be explained?

A

1) No reduction of nitrate

Instead, the zinc ( a strong reducing agent), reduced the nitrate, creating the red colour. The organism has no affect.

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20
Q

After addition of nitrate reagents 1,2 and ZINC, the nitrate broth turns COLOURLESS, what happened?

A

Presence of a DENITRIFIER (No3–>N2)

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21
Q

The IMViC tests are a series of _____ to differentiate _____

A

4 test tubes

members of Gram - intestinal bacteria

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22
Q

What does the indole test detect in tryptophan broth?

A

Production of indole from the amino acid tryptophan found in the tryptophan broth.

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23
Q

What does the methyl red test detect in the MR-VP?

A

Provides an indication of the extent of acid production from the glucose found in the mdeium

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24
Q

What do the 4 testubes contain in the IMViC tests?

A

1) Tryptophan broth
2) Methyl Red (MR-VP)
3) Voges-Proskeur (MR-VP)
4) Citarte (Simmons citarte agar)

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25
Q

After addition of methyl red to MR-VP, the solution turns pink, what happened?

A
  • Acid production

- E.coli

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26
Q

After addition of methyl red to MR-VP, the solution turns remains colourless, what happened?

A
  • No acid production

- E. Aeurogenas

27
Q

After addition of VPI and VPII to MR-VP, the solution turns pink. what happened?

A

Production of acetyl methyl carbinol

28
Q

What does the citrate test indicate?

A

Whether the organism can use citrate as a sole carbon source

29
Q

After inoculate of the citrate tube, the solution turns bright blue? What does this mean? What does a green product indicate?

A

Bright blue = organism can use citrate as its only v=carbon sure
Green = negative test

30
Q

Staph. aureus is gram ___ and produces ___ from ____. Its is ___ to NacL

A

Positive
Acid
Mannitol
Resistant

31
Q

Staph, epidermis is gram _____ is resistant to _____

A

Positive

NaCL

32
Q

E. coli is gram ____ and produces ___ from ____. Its is ____ to NaCL

A

Negative
Acid
Lactose (MacConkey fermenter)
Sensitive

33
Q

Pseudomonas is gram ___ and produced ___ from lactose and is sensitive to NaCL.

A

Negative

No acid

34
Q

API 20E system does what?

A

A differential method for identification

35
Q

ONPG positive test =

A

Yellow colour, presence of beta-galactoside

36
Q

ADH positive test =

A

pH increase, arginine dihydrolase which converts arginine -> ornithine, ammonia and CO2

37
Q

LDC positive test =

A

pH increase, lysine decarboxylase

38
Q

ODC positive test =

A

PH increase, ornithine decarboxylase

39
Q

URE positive test =

A

pH increase, urease

40
Q

TDA positive test =

A

Brown.red colour, tryptophan deaminase

41
Q

GEL positive test =

A

Degradation of gelatin and pigment diffuses through medium, presence of gelatinesa enzyme

42
Q

OXI positive test =

A

Purple colour, indicates oxidation of TMPD and presence of cytochrome C

43
Q

CAT positive test =

A

bubbles, presence of CATALASE which degrades hydrogen peroxide (toxic from of oxygen)

44
Q

What are 3 physical methods?

A

Moist heat
Dry Heat
UV light

45
Q

What happens when microbes are exposed to moist heat?

A

Coagulation of proteins

46
Q

What happens when microbes are exposed to dry heat?

A

Oxidation of cell components

47
Q

What happens when microbes are exposed to UV light?What happens during photo reactivation?

A

Dimerization of THYMINE

During photo reactivation, culture is exposed to visible light

48
Q

Exposure of cultures to UV light is ___

A

Bactericidal

49
Q

UV light is ___

A

Non ionizing

50
Q

HEPA filters are used to sterilize ?

A

Air, by flowing through laminar flow sterile cabinets

51
Q

How can liquids be sterilized WITHOUT heat?

A

By passing through membrane filters

52
Q

What is more rapid, moist heat or dry heat? Are vegetative or spores more susceptible to temperature? Why?

A

Moist > Dry

Vegetative cells, because of their higher water content (Spores are dried out)

53
Q

Can sunlight be damaging to microorganisms?

A

Yes, since it contains non-ionizing UV light

54
Q

Spores are moe ___ to physical methods

A

Resistant

55
Q

What is the chemical method?

A

Evaluation of microbial chemical agents; time to kill bacteria

56
Q

What is the disk test assay?

A

Using antibiotics, measures the antibiotic Susceptibility spectrum

57
Q

What were the 4 antibiotics tested?

A

Chloramophenical (Peptide elongation inhibited by targeting 23S on 50S subunit of ribosome)

Streptomycin (An aminoglycoside, targets 30S subunit and causes mRNA misread - bactericidal)

Tetracycline (Targets 30S subunit, inhibits protein synthesis)

Penicillin (Beta lacta, binds to transpepetidase and inhibits synthesis of peptidoglycan during bacterial growth phase)

58
Q

Disk assay methods are useful to … (2)

A

1) Determine which antibiotic would be effective in treating infection
2) Aid in identification of microbes

59
Q

If ampicillin (a) has an inhibition diameter of ___ mm the organism is ____

A

< 11 = resistant
12-13 = intermediate
> 14 = Sensitive

A= for gram -, such as E.coli

60
Q

If ampicillin (b) has an inhibitor diameter or ___ mm the organism ___

A 
<28 = resistant
>29 = sensitive
61
Q

If Penicillin (g) has an inhibitor diameter or ___ mm the organism ___

A

<20
21-28 = intermediate
>29 = resistant

62
Q

If chloramphenicol has an inhibitor diameter or ___ mm the organism ___

A 
<12 = resistant
13-17 = intermediate
>18 = sensitive
63
Q

An organism being RESISTANT to an antibiotic means that …..

A

There is a SMALL diameter of inhibition

64
Q

An organism being SENSITIVE to an antibiotic means that

A

there is a LARGE diameter of inhibition

2) Introductory Microbiology COPY (24 decks)

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