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BACTE LAB > Wk 4 > Flashcards

Wk 4 Flashcards

1
Q

Bacteria where their needs are complex and
relatively complex, and exceptional media components
must be used for growth

A

Fastidious

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2
Q

– Bacteria where their needs are relatively
basic and straightforward

A

Nonfastidious

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3
Q

is an aqueous solution to which all the
necessary nutrients required for growth of micro-
organisms have been added

A

culture medium is an aqueous solution to which all the
necessary nutrients required for growth of micro-
organisms have been added

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4
Q

Example of liquid media

A

Pectin water and nutrient broth

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5
Q

(prepared by adding 0.2-0.5% agar
to the liquid medium.

A

Semi-solid media

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6
Q

disadvantage and advantage of liquid medium

A

Disadvatage:
- Growths of bacteria do not exhibit special
characteristic appearances and hence, are difficult
to identify
- Isolated colonies can’t be separated from a liquid
medium
o Advantage:
- Different micro-organisms give distinct appearances
in the form of colonies which are very useful in
identification
- Indispensable for the isolation of pure cultures
(microorganisms are easily separated and grown as
a pure line, thus helping an identification

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7
Q

support the growth of
micro-organisms that do not have special
nutritional needs

A
  • Basic or basal media
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8
Q

Mainly used maintaining stock cultures of control
strains of bacteria and for subculturing of
bacteria from selective media

A
  • Basic or basal media
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9
Q

n inhibitory substances added
to them which inhibit the growth of unwanted
bacteria and only promote the growth of
pathogenic or disease-causing bacteria

A
  • Selective media
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10
Q

These are used for sites which have a normal
microbial flora to prevent the growth ofunwanted
bacteria overcrowding the pathogenic bacteria

A
  • Selective media
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11
Q

o Ex. DCA medium for Dysentery bacilli

A
  • Selective media
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12
Q

These media have certain substances or
indicators added to them which help to
differentiate between bacteria by a color change

A

Indicator or differential media

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13
Q

o Ex. MacConkey media

A

Indicator or differential media

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14
Q

Media used to transport specimens from the
patient’s bedside or health centers to a
microbiology laboratory

A
  • Transport media
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15
Q

media used in transport media

A

Usually semi-solid media which promote the
growth of certain delicate organisms which might
usually not survive the time taken for
transportation

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16
Q

Prevent the pathogenic bacteria to be overgrown
by commensal bacteria

A
  • Transport media
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17
Q

Ex. Cary-Blair’s medium u

A
  • Transport media
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18
Q

used for transportation
and preservation of enteric bacteria

A

Cary-Blair’s medium

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19
Q
  • Separate room should be dedicated for
A

o Preparation of culture media
o Pouring of culture media
o Sterilization of culture media

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20
Q

In the preparation of complex culture media, what media should be used

A

In the preparation of complex culture media, ready-made
standardized dehydrated media can be used to ensure
good performance and reproducibility

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21
Q

how many media is suggested for a
basic microbiology laboratory

A

minimum of five dehydrated media

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22
Q

`tend to absorb moisture from the air
and are sensitive to heat, light and extreme changes in
temperature

A

Dehydrated media

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23
Q

o Follow the storage conditions as indicated for dehydrated media

A
  • Below 25°C in a dry area
  • Away from direct sunlight, autoclaves, hot-air
    ovens, other heat sources
  • Use the stock in lot/batch number order (product
    with earlier batch number should be opened first)
  • Note on the label the container is first opened
  • Order the medium in an appropriate size o
    container
  • A large container which is opened several times
    will spoil the medium overtime
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24
Q

o It is advisable to prepare

A

one week’s requirement only

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25
Q

how to prepare media and volume

A

Prepare the medium in a container which is about twice
the final volume of the medium needed so that the dry
powdered medium can be adequately mixed

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26
Q

Dry culture media powder which does not dissolve

A

might not be sterilized in the autoclave and can be a
source of contamination

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27
Q

Media containing agar should be heated first to

A

completely dissolve the agar before autoclaving

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28
Q

Most culture media will require final sterilization in an

A

autoclave at 121°C for 20 minutes

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29
Q

Do not adjust the ____of dehydrated media prior to
sterilization

A

ph

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30
Q

A liquid medium can be tested by

A

dipping a narrow
range pH paper into a sample of the medium at room
temperature and comparing the color of the paper
against the pH color chart provided

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31
Q

agar medium can be tested by

A

laying a narrow
range pH paper on its surface after it has solidified

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32
Q

used to make blood agar and chocolate
agar, etc

A

Nutrient agar

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33
Q

mostly used as an indicator medium
for gram negative bacteria

A

MacConkey agar

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34
Q

Sensitivity test agar (Mueller-Hinton agar) –

A

for
antimicrobial sensitivity testing

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35
Q

selective medium for growth
of enterobacteria like Salmonella and Shigella

A

Deoxycholate citrate agar

36
Q

Over-heating of the media should be avoided as i

A

may cause the formation of toxic products due to
chemo-oxidation

37
Q

it is preferred to work within an

A

inoculation hood or cabinet
filled with a filtered air supply

38
Q

heat the mouth of the container from which the
medium is being poured in a flame for making

A

a slant or a
slope

39
Q

To reduce condensation of water on the lids, the media
should be at what temp

A

cooled down to 52°C before pouring

40
Q

ayer of moisture is undesirable and should be removed
by drying the set plates in a drying cabinet at what temp

A

60°C for 15-30 mins

41
Q

Screw-capped bottles of nutrient broth and agar can be
stored for

A

6 months at low ambient temperatures (12-16°C).

42
Q

Agar plates should be stored at __________
to avoid loss of moisture.

A

Agar plates should be stored at 2-8°C in sealed containers
to avoid loss of moisture.

43
Q

The pH of the prepared medium in its final form at an
ambient temperature of _______should lie within the range
given on the product labe

A

The pH of the prepared medium in its final form at an
ambient temperature of 25°C should lie within the range
given on the product labe

44
Q

STERILITY
A few plates, tubes or bottles prepared from each lot or
batch should be incubated for _________________

A

A few plates, tubes or bottles prepared from each lot or
batch should be incubated for 2-5 days at 35-30°C and 50-
55°C

45
Q
  • For a lot of 100 or less units, _______ should be tested
A
  • For a lot of 100 or less units, 3-5% units should be tested
46
Q

For a larger lot, _________ should be tested
for sterility

A

For a larger lot, 10 random plated or tubes should be tested
for sterility

47
Q

For testing new lots or batches of media,

A

inoculate old and
new lots in together and compare the performance of the
two lots side by sid

48
Q

To test whether the medium prepared supports the growth
of bacteria,

A

inoculate a few units with appropriate stock
cultures or fresh isolate

49
Q

Chiefly used as the basal medium for carbohydrate
fermentation tests

A
  • Peptone water
50
Q

o Used to test the formation of indole

A
  • Peptone water
51
Q

Usually supplied as golden granular powder with a low
moisture content and gives a pH between 5 and 7 in a
1% solution

A
  • Peptone water
51
Q

o It is hygroscopic

A
  • Peptone water
52
Q

peptone waterph

A

gives a pH between 5 and 7 in a
1% solution

53
Q
  • If you are preparing peptone water, the recipe is
A

o Peptone, 10g
o NaCl, 5g
o Water, 1L
o Dissolve the ingredients in warm water and adjust the
pH to 7.4-7.5
o Filter and distribute as required
o Autoclave at 121°C for 15 minutes

54
Q

o Reconstitute the dehydrated nutrient broth
according to manufacturer’s instructions

o Add 2% agar to the solution

o Heat to completely dissolve the agar

A
  • Nutrient agar
55
Q

part from being an enriched medium, it also is used
as an indicator medium to study the haemolysis of
bacteria like Staphylococcus aureus and
Streptococcus pyogenes

A
  • Blood agar
56
Q

Blood used for the preparation of blood agarshould
be as fresh and stored at what temp

A

Blood used for the preparation of blood agarshould
be as fresh and stored at 2-8°C

57
Q

RECOMMENDED BLOOD FOR BA IS

A

Defibrinated blood is recommended for use rather
than blood containing an anticoagulant

58
Q

CONCENTRATION OF BLOOD FOR BA

A

o Concentrations can vary from 5-50% although10%

59
Q

WHAT TEMP FOR INCUBATING BA

A

o Incubate at 35°C

60
Q

At 100ml blood to 1L of sterile agar base, agar willtend
to s

A

agar willtend
to settle at the bottom of the flask, so all flasks should
be swirled to facilitate proper mixing of agar and
aeration of blood. Pour into plates after

61
Q

Prepared from blood agar by heating and contains
certain extra nutrients required for growth of fastidious organisms like Neisseria and Pneumococcus

A
  • Chocolate agar
62
Q

how o cool choco agar

A

Cool it in a water bath at 75°C at 10% sterile blood

63
Q

he heat causes red cells to lyse and release the
nutrients

A

chocolate agar

64
Q

medium turns chocolate brown within—————
Then pour into plates.

A

10 minutes.

65
Q

o Used for the cultivation of enterobacteria

A
  • McConkey Agar
66
Q

Contains bile salts which inhibit the growth of grampositive bacteria and promotes growth of only gramnegative bacteria

A
  • McConkey Agar
67
Q

dye of macconkey

A

Contains a dye called neutral red which gives a pink
color to colonies of lactose-fermenting bacteria

68
Q

autoclaving of macconkey

A

Heat in autoclave with free steam (100°C) for 1 hour
and then 115°C for 15 minutes.

69
Q

solation of bacteria in pure culture from clinical
specimens

A

Streak Culture

70
Q

inoocluation loop type

A

Platinum, Nichrome wire or plastic disposal wire loop is
used

71
Q
  • Provides a uniform surface growth of the bacterium.
A

Lawn Culture

72
Q

Used for for bacteriophage typing or antibiotic sensitivity
testing

A

Lawn Culture

73
Q

Also used in the preparation of bacterial antigens and
vaccines

A

Lawn Culture

74
Q

Lawn cultures are prepared by

A

flooding the surface of the
plate with a liquid suspension of the bacterium

75
Q

pour plate melting req

A
  • Agar medium is melted (15 ml) and cooled to 45oC.
76
Q

ml of inoculum added for pour plate method

A
  • 1 ml of the inoculum is added to the molten agar.
77
Q

pour plate method incubation

A
  • Plates are incubated at 37oC
78
Q

It gives an estimate of the viable bacterial count in a
suspension.

A

Pour Plate Method

79
Q
  • Used for quantitative urine cultures.
A

Pour Plate Method

80
Q
  • Sample is pipetted onto the surface of an agar.
    What method
A

Spread Plate Method

81
Q

are inoculated by touching with a charged
loop or by adding the inoculum with pipettes or syringes.

A

Liquid cultures

82
Q

Used for Blood culture, Sterility tests or for continuous
culture methods

A

Liquid Culture

83
Q

Disadvantage: It does not provide a pure culture from
mixed inocula

A

Liquid Culture

84
Q

Done in Kirby-Bauer Disk Diffusion method of Antibiotic
Sensitivity

A

Lawn Culture Technique

85
Q

Lawn Culture Technique agar used

A

Lawn Culture Technique

86
Q

Streak perpendicular

A

lawn culture

BACTE LAB (4 decks)

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