Lab #14 Flashcards

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1
Q

Indole Production Test

Add Kovac’s reagent, gently shake, but keep reagent on top of broth

Pink ring indicates

a) Positive
b) Negative

A

a) Positive

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2
Q

Indole Production Test

Add Kovac’s reagent, gently shake, but keep reagent on top of broth

Yellow ring indicates

a) Positive
b) Negative

A

b) Negative

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3
Q

Indole Production Test

Pink ring in broth

A

= positive

= has Trp-ase

  • E. coli vs. other enteric bacteria
  • Proteus mirabilis vs. other Proteus spp.
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4
Q

Indole Production Test

Yellow ring in broth

A

= negative

= does not have Trp-ase

  • E. coli vs. other enteric bacteria
  • Proteus mirabilis vs. other Proteus spp.
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5
Q

Methyl Red Test

Add methyl red growth culture; gently shake

Red indicates

a) Positive
b) Negative

A

a) Positive

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6
Q

Methyl Red Test

Add methyl red growth culture; gently shake

Yellow indicates

a) Positive
b) Negative

A

b) Negative

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7
Q

Methyl Red Test

Red

A

= positive

= pH < 5

= presence of acids

= has FHase

Klebsiella spp./Enterobacter aerogenes (-) vs. E. coli (+)

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8
Q

Methyl Red Test

Yellow

A

= negative

= pH > 6

= no acids produces

= lacks FHase

Klebsiella spp./Enterobacter aerogenes (-) vs. E. coli (+)

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9
Q

Carbohydrate Fermentation Test

Medium

A

Bromocresol purple (BCP) “carbohydrate” broth

(BCP = color pH indicator)

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10
Q

Carbohydrate Fermentation Tests

purple → yellow

a) positive
b) negative

A

a) positive

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11
Q

Carbohydrate Fermentation Tests

still purple…

a) Positive
b) Negative

A

b) Negative

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12
Q

Carbohydrate Fermentation Tests

Inoculate BCP lactose broth

purple → yellow

A

= positive

= pH change (acidic)

= ferments lactose

All Enterobacteriaceae ferment lactose!

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13
Q

Carbohydrate Fermentation Tests

Inoculate BCP lactose broth

still purple…

A

= negative

= no pH change

= does not ferment lactose

All Enterobacteriaceae ferment lactose!

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14
Q

Motility Test

Growth away from stab =

a) motile
b) non-motile

A

a) motile

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15
Q

Motility Test

Growth at stab =

a) motile
b) non-motile

A

b) non-motile

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16
Q

Urease Test

Yellow =

a) Urease( - )
b) Urease( + )

A

a) Urease( - )

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17
Q

Urease Test

Pink =

a) Urease( - )
b) Urease( + )

A

b) Urease( + )

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18
Q

Control of Microbial Growth

_____ _____ are used for control of microbial growth

A

Chemical agents

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19
Q

Control of Microbial Growth

Antiseptics are mild enough to be used on skin and living tissue

True

False

A

True

20
Q

Control of Microbial Growth

Examples of antiseptics are:

A

iodine

hydrogen peroxide

alcohol

21
Q

Control of Microbial Growth

Disinfectants are toxic for living organisms

True

False

A

True

22
Q

Control of Microbial Growth

Disinfectants are used on inanimate objects

True

False

A

True

23
Q

Control of Microbial Growth

Examples of disinfectants

A

chlorine bleach

phenol

formaldehyde

24
Q

Control of Microbial Growth

Bactericidal: completely _____ bacteria

A

completely kills bacteria

25
Q

Control of Microbial Growth

Bactericidal substances

A

antiseptics

disinfectants

26
Q

Control of Microbial Growth

Bactericidal processes

A

autoclaving

boiling

27
Q

Control of Microbial Growth

Bacteriostatic: temporarily _____ further growth of bacteria

A

inhibit

28
Q

Control of Microbial Growth

Bacteriostatic substances

A

antibiotics (inhibition of bacterial growth → immune cells kills the remaining cells)

29
Q

Control of Microbial Growth

Bacteriostatic processes

A

refrigeration

30
Q

Antibiotics

Definition of antibiotic

A

Natural antimicrobial agents produced by microbes (e.g. penicillin, from Penicillium notatum—a mold)

31
Q

Antibiotics

Antibiotics are safe enough to be ingested

True or False

A

True

32
Q

Antibiotics

Antibiotics can be _______ or _______

A

bacteriostatic or bactericidal

33
Q

Antibiotics

Bacteriostatic antibiotics at a ____ enough concentration can be bactericidal

A

high

34
Q

Antibiotics

Bactericidal antibiotics at ____ enough concentration can be bacteriostatic

A

low

35
Q

Antibiotics

Achieve antimicrobial effect by one of the following mechanisms:

1.

2.

3.

4.

5.

A
  1. Inhibiting cell wall synthesis
  2. Inhibiting protein synthesis
  3. Alteration of cell membranes
  4. Inhibition of nucleic acid synthesis
  5. Interfering with metabolic pathways
36
Q

Antibiotics

Broad spectrum: effective against a _____ variety of different bacteria

* Neomycin and tetracycline affect both Gm(+) and Gm(-) bacteria

a) wide
b) particular

A

a) wide

37
Q

Antibiotics

Narrow spectrum: effective against a _____ group of bacteria

* Rifamycin – tuberculosis-causing bacteria

* Bacitracin(found in Neosporin® )- Gm(+) bacteria only

a) wide
b) particular

A

b) particular

38
Q

Antibiotic Sensitivity Test

Why is it used?

What does it help understand?

Why do hospitals use them?

A

Used to estimate effectiveness of known antibiotics vs. certain bacteria

Helps in understanding which antibiotic(s) will be most effective in combating bacterium in question

Hospitals routinely perform ASTs to decide on the most effective treatment plans

39
Q

Kirby-Bauer Method

Also known as the _____ _____ _____ of antibiotic sensitivity testing

A

disc diffusion method

40
Q

Kirby-Bauer Method

_____ _____ soaked with a known amount of antibiotic at _____ _____

A

Paper discs

various concentrations

41
Q

Kirby-Bauer Method

Disc on plate → antibiotic diffusion into agar

A

diffusion into agar

42
Q

Kirby-Bauer Method

Concentration of antibiotic _____ with distance from disc

a) increases
b) descreases

A

b) decreases

43
Q

Kirby-Bauer Method

Same microbe spread over entire plate

If A, B, and C are the same antibiotic at different concentrations,

then in order of _____

a) concentration
b) effectiveness

A

a) concentration

B > C > A

44
Q

Kirby-Bauer Method

Same microbe spread over entire plate

If A, B, and C are the different antibiotics at the same concentration,

then in order of _____

a) concentration
b) effectiveness

A

b) effectiveness

B > C > A

45
Q

Kirby-Bauer Method

Effectiveness of antibiotic is measured in size of _____ __ _____

A

ZONE OF INHIBITION

46
Q

Kirby-Bauer Method

Bacterial growth is _____ in the presence of the antibiotic

a) inhibited
b) allowed

A

a) inhibited

47
Q

Zone of Inhibition

A