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micro 187 maddie > LO2 > Flashcards

LO2 Flashcards

1
Q

A culture medium is a substance that contains

A

contains the nutrients which will support the growth and reproduction of bacteria

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2
Q

types of media chosen for specimens arriving in the microbiology are chosen based on 3:

A

-the character of organism
-source
-cost and effect

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3
Q

2 categories of media

A

defined
undefined

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4
Q

define media

A

you know whats in it bc u make it
not really used in lab

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5
Q

undefined media

A

made from partial digests from animal and veg proteins

also given growth factors

used most often

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6
Q

3 forms of media

A

solid
semi solid
liquid

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7
Q

solid media

A

allow bacteria to grow immobolozed for the isolation of single colonies

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8
Q

solid media 5 solidifying agents GAAPP

A

agar
gelatin
potato
agarose
polyacrylic gels

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9
Q

most common solidifying agent

A

1-2% agar , if 5% can inhibit spread
made from red marine algae
melts at 95 and solidifies at 50 and less
solid media will liquefy

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10
Q

gelatin

A

can be hydrolyzed/made liquid by enzymes of some bacteria

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11
Q

potato

A

used with nutrient solutions such as egg or serum and coagulated by inspissation which is the heating of high protein

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12
Q

agarose

A

galactose polysaccharide prepared by washing and extracting refined agar

Used for immunological procedures such as electrophoresis.

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13
Q

polyacrylic gels

A

chemically defined and used for research

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14
Q

semi solid media

A

-very little agar 0.05-0.3, lets some air in
-allows for growth of aerobic, anaerobic and microaerophilic organisms
-movement of motile organisms

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15
Q

liquid media / broth

A

enhances growth if you have very little source and allows movement and microscopic observations but nit sep/ or identification

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16
Q

Simple or Supportive media

A

Basic media which will support the growth of non-fastidious organism

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17
Q

enriched media

A

basic media plus extra nutrients that were added to support the growth of fastidious organisms

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18
Q

differential media

A

Basic media which contain a substance(s) which differentiates similar organisms through
metabolism (like lactose metbolism)

Often they are made visible with a chemical indicator via a pH change

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19
Q

Selective or Inhibitory

A

Basic medium to which chemicals or antibiotics are added to select particular organisms
by inhibiting others or to enhance the growth of particular organisms at the expense of
others

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20
Q

Other 3 methods used to render media selective:

A

selective incubation temp
increased chem concertation in media
increasing or dec pH

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21
Q

Enrichment -always liquid

A

allow one type of organism (pathogen) to grow freely while inhibiting others (normal flora)

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22
Q

other 2 methods of enrichment

A

heat shock: heat broth up kill most except for desired
cold enrichment: incubating at 4C

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23
Q

transport media

A

keeping microorganisms viable while specimens
are being transported to the testing lab

-enough to survive but not multiply

For swabs: Amies, Amies with charcoal, viral transport media
For feces: Cary-Blair, Sodium Acetate Formalin (SAF)
For urine: boric acid, sodium formate, glycerol

24
Q

chart of medias

A
25
Q

6 Components of Culture Media
1. hydrogen source

A

from oxidizing subs/ glucose

26
Q

6 Components of Culture Media
2. carbon source

A

-carbs : glucose, lactose, sucrose
-also givese energy

27
Q

6 Components of Culture Media

  1. nitrogen source
A

peptones from hydrolysis of proteins

ex trypticase peptone

28
Q

6 Components of Culture Media

  1. energy / minerals source
A

-salts

Ca: for gram + walls
iron: virulence
Mg and Ca: ribosomes
Phospho: phosphate for ATP and co-enzymes
Sulfur: sulfates for proteins
most for enzyme activators

29
Q

6 Components of Culture Media

  1. Sodium Cl, NaCl
A

osmotic
buffer

30
Q

6 Components of Culture Media

  1. water
A

sterile distilled
demineralized

no tap

31
Q

Other Media Components and Considerations

  1. growth factors
    yeast
    blood
    serum
    Casein hydrolysate
    Hemin x factor and NAD V factor
A

yeast: Vit B, a.a, inorganic salts

blood: hemoglobin

serum: impt for initial growth, gives nutrients and albumin which protects cells from toxic shit

casein: from milk protein hydrolysis, has a.a

X and V: heating of blood, or fildes peptic digest

32
Q

Other Media Components and Considerations

  1. selective agents
A

further enhance the growth of pathogenic
organisms or to inhibit the growth of normal flora

-Chemicals and antimicrobial agents are frequently used as selective agents

33
Q

Other Media Components and Considerations
3. pH indicators

A

bacteria metabolise certian ingr and them produce a diff ph the change of pH is noted by a color change

34
Q

dehydrated media

A

some come ready but others need to be re-constituted and sterilized and poured into plate or

poured into tubes and then sterilized/ autoclave

35
Q

general steps to prepare media

A

-how much do you need
-calc how much each ingr
-assemble equip
-weigh
-add to flask mix and add remaining
-sterilize and dispense or opp
-cool

36
Q

notes on storing media

A

at 4C
bagged to avoid dehydration
checking pH and sterility using QC methods

37
Q

common pH for bac

A

6.5-7.5

if pH is increased due to bac metabolic activity the bac can die

38
Q

monitor pH
pH meteres

A

-at room temp
-after sterilization
-surface electrode is put in

39
Q

monitor pH
chemical indicators 4 types

A

phenol red
neutral red
bromothymol blue
bromcresol purple

40
Q

2 most widely used indicators to determine oxidation-reduction are

A

methylene blue
resazurin

41
Q

Sterilization is achieved by 2

A

autoclave
filter

42
Q

autoclaving

A

Reconstituted media is heated to 121°C
and sterilized with steam under pressure
(15 lbs/sq. inch) for a min. of 15 minutes

43
Q

memrbane filtration

A
  • Used for sterilizing media components that are heat labile ( antibiotics, carbohydrates, serum and urea)
  • Liquid is forced through the filter (0.2 to 20 µm) by suction or pressure
  • Contaminants get trapped in the filter
  • The filtrate is then added to other media
    ingredients that are already sterilized and
    cooled
44
Q

dispensing media

test tube vs plate vs slant

A

tube: before sterilization, capped after

plate: after sterile, anti-foam agents, above 50 C

slant: after sterile, caped and palced on angle

45
Q

QC culture media should be

A
  • be sterile
  • be clear and/or of proper colour, consistency, depth, no hemolysis and no bubbles
  • support the growth of organisms likely to be in the specimens tested
  • if specified, inhibit the growth of commensal organisms
  • if specified, give a typical biochemical response
  • be stable
  • have a reasonable shelf life
46
Q

GC dehydrated media

The following should be monitored and permanent documentation should be maintained

A
  • amount used
  • lot number and expiry date
  • method of sterilization
  • quantity prepared
  • initials of preparer
  • date of preparation
47
Q

Sterility Testing

A

5% of the batch if the batch is 100 units or fewer. If greater 10% is tested

Sterility testing is typically not performed on commercially prepared media

checked for signs of bacterial or fungal growth

is seen get rid all

48
Q

Gross appearance check for sterilization

Common causes of error include:

A
  • incorrect pH
  • excessive heating during sterilization and in water baths
  • errors in concentration of ingredients
  • addition of heat-labile enrichments when the base medium is too hot
  • cooling of agar medium below 45°C before pouring into plates
  • insufficient cooling before pouring
  • improper mixing
49
Q

Growth Performance

A

known organisms done by using stock cultures obtained from the American Type Culture Collection (ATCC) or commercial

also used for fastidious organisms

important to inoculate the media with organisms that should be positive for growth but also ones that should be negative for growth

50
Q

Biochemical Properties QC

A

Reference ATCC organisms should demonstrate the biochemical reactions for which the medium
is intended.

51
Q

Quality Control of Commercially Prepared Media

A

The CLSI (Clinical and Laboratory Standards Institute) Subcommittee on Media Quality Control have compiled a list of media which have been manufactured following CLSI guidelines.

They are ready for use without re-testing sterility and performance. The manufacturer must supply documentation stating the adherence to the CLSI Standards.

The shipment must be visually inspected for
dehydrated media, cracked petri dishes, hemolysis, consistency, depth, bubbles, clarity and
contamination.

52
Q

Stability can be effected by 3

A

temp: refrig most
dehydration: media wrapped in plastic or capped, upside down
rotation: old and new

53
Q

QM

QM begins from the moment the physician requests microbiology testing and continues
through collection and transport of specimens, timely reporting and interpretation of data to
provide quality patient care at a minimum cost.

Guidelines must be established and maintained for the following:

A
  1. speciment
  2. lab eq
  3. temps
  4. incubator CO2
  5. pH
  6. sterility
  7. calibrations of eq
  8. centrifuge speed
  9. stain
  10. BSF
  11. test strips and agars
  12. reagents and antisera
  13. Automated Instruments and Commercial Identification Kit
54
Q

proficiency tests 2 types

A

internal and external

55
Q

internal proficiency

A

randomly placed in workflow by workers within in a known sample

56
Q

external proficiency

A

C.A.P. specimens - The College of American Pathologists : packages sent at
intervals to determine their accuracy and compare their capabilities with other labs

L.C.D.C. Proficiency Specimens - from the Laboratory Centre for Disease Control in Winnipeg: have both odd and normal, sent in groups of 5 pure isolates and given time, can compare with others from Canada

micro 187 maddie (10 decks)

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