Culture Media Preparation (M) Flashcards by Henrie C. Cruz

True or False.

Diff pathogenic bacteria have same nutritional needs, various types of culture media have been developed for use in diagnostic microbiology

False, because diff pathogenic bacteria have diff nutritional needs

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What are fastidious bacteria?

These are bacteria that have relatively complex needs and exceptional media components must be used for growth

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What are nonfastidious bacteria?

These are bacteria whereas the nutritional needs of most clinically important bacteria are relatively basic and straightforward

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What is the definition of the term culture?

It is a term given to microorganisms that are cultivated in the lab for the purpose of studying them

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What is the definition of the term medium?

It is a term given to the combination of ingredients that will support the growth and cultivation of microorganisms by providing all the essential nutrients required for growth (that is, multiplication) in order to cultivate these microorganisms in large #s to study them

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How will the medium support the growth and cultivation of microorganisms?

By providing all the essential nutrients required for growth

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What are the diff classifications of media based on their physical state?

1) Broth (liquid)
2) Agar (solid)
3) Semi-solid
4) Bi-phasic

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What is the composition of broth (in terms of agar)?

No agar is present

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What is the composition of agar (in terms of agar)?

0.5 - 1.5 % agar

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What is the composition of semi-solid (in terms of agar)?

0.2 - 0.4 % agar

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What is the composition of bi-phasic (in terms of agar)?

Both liquid and solid

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What is the interpretation for the ff circumstances:

a) Clear broth
b) Turbid broth

a) Indicating no bacterial growth

b) Indicating bacterial growth

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What are the classifications based on methods of dispensing?

1) Plated medium

2) Tube Media

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What are the components of tube media?

1) Butt
2) Butt / Slant
3) Slant

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What are the diff classifications of media (based on their functions)?

1) Enrichment media
2) Supportive media
3) Selective media
4) Differential media
5) Transport media

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What is the characteristic of enrichment media?

It contains specific nutrients required for growth of particular bacterial pathogens that may be present alone or w/ other bacterial spp in a pt sx

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What is the purpose of enrichment media?

This media type is used to enhance the growth of a particular bacterial pathogen from a mixture of organisms by using nutrient specificity

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What are the exs of enrichment media?

1) Choc agar
2) SBA
3) Sel-F
4) Alkaline Peptone water
5) BCYE

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What is the characteristic of supportive media and its function?

It contains nutrients that support growth of most nonfastidious organisms w/out giving any particular organism a growth advantage

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What is an ex of supportive medium?

Thioglycollate broth

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What is the characteristic of selective media and its function?

1) It contains 1 or more agents that are inhibitory to all organisms except those being sought
2) In other words, these media select for the growth of certain bacteria to the disadvantage of others

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Does selective media contain inhibitory agents?

Yes

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What are the inhibitory agents present in selective media?

1) Dyes
2) Bile salts
3) Alcohols
4) Acids
5) Antibiotics

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What are the exs of selective media?

1) DCA
2) LJ medium
3) HE
4) MSA
5) XLD
6) BCYE

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What is the characteristic of differential media (or why is this called differential)?

This agar is also differential because the appearance of colonies produced by certain bacterial spp is readily distinguishable

What is the purpose (or action) of differential media (or why is it called differential)?

It employs some factors (or factors) that allows colonies of 1 bacterial spp or type to exhibit certain metabolic or culture characteristics that can be used to distinguish them from other bacteria growing on the same agar plate

What are the exs of differential media?

1) McConkey 2) EMB 3) MSA

What is the purpose of transport media?

These are used to maintain the viability of certain delicate organisms in clinical sxs during their transport to the lab

What are the characteristics of transport media?

They typically contain only: 1) Buffers and 2) salt They lack: 1) Carbon 2) Nitrogen 3) Organic growth factors

Does transport media facilitate microbial multiplication? Why or why not?

No, these type of media does not facilitate microbial multiplication because these lack carbon, nitrogen, and other organic growth factors

Provide an ex of transport medium

Stuart's transport medium for Neisseria gonorrhea (or gonorrhoeae)

If media are not purchased, can lab personnel prepare agars and broths?

Yes

How does lab personnel prepare agars and broths?

By using dehydrated powders that are reconstituted in H2O (distilled or deionized) accdg to manufacturer's reccos

What types of H2O are used for preparation of agars and broths?

1) Distilled | 2) Deionized

What is the general idea (or concept) for preparing agars?

Generally, media are reconstituted by dissolving specified amt of media powder, w/c usually contains all necessary components, in H2O

Where are the necessary components (in agar preparation) usually present?

In the media powder

Where are the necessary components (in agar preparation) usually present?

In the media powder

What is the importance (or purpose) of boiling (in preparation of agar)?

It is often required to dissolve the powder, but specific manufacturer's instructions printed in media package inserts should be followed exactly

Where are the specific manufacturer's instructions placed?

These are printed in media package inserts

Does most media require sterilization?

Yes

Why is sterilization required for most media?

So that only bacteria from pt sxs will grow and not those that are contaminants from H2O or the powdered media

When should the timing of autoclave sterilization start?

The timing of autoclave sterilization should start from the moment the temp reaches 121 DC and usually requires a minimum of 15 mins

What should be done once the sterilization cycle is completed?

Molten agar is allowed to cool to approx 50 DC before being distributed to individual petri plates (usually 25 mL of molten agar per plate)

After the sterilization cycle, the molten agar is cooled to approx what temp?

50 DC

What is the concentration (or density) of molten agar per plate?

Usually 25 mL

What should be done if other ingredients are to be added (to the culture medium)?

They should be incorporated when the molten agar has cooled, just before distribution to plates

What are the exs of other ingredients (that are added to culture medium)?

Supplements such as: 1) Sheep blood or specific vitamins 2) Nutrients 3) Antibiotics

What are the 3 types of hemolysis present in SBA?

1) Beta hemolysis 2) Alpha hemolysis 3) Gamma hemolysis

What is the general purpose of SBA?

For isolation of microorganisms

What are the purposes (and what types of medium) of Mac?

Selective and differential for the isolation of gram (-) bacilli

What are the purposes (or what types of medium) of EMB?

Selective and differential

What are the purposes (or what types of medium) of TCBS?

Selective and differential for Vibrio, Plesiomonas, and Aeromonas

What are the bacteria that can be detected (or can be present) in TCBS?

1) Vibrio cholerae | 2) Vibrio parahaemolyticus

What are the purposes (or what types of medium) of Salmonella Shigella agar?

Selective and differential for Salmonella and Shigella spp

What are the bacteria that can be detected (or can be present) in Salmonella Shigella agar?

1) Salmonella | 2) Shigella

What are the results in Simmon's Citrate agar?

1) Negative | 2) Positive

What are the results in urea agar?

1) Uninoculated or negative 2) Negative 3) Positive

What are the bacteria that can be detected (or can be present) in SIM?

1) Escherichia coli 2) Micrococcus luteus 3) Proteus mirabilis

What are the results in DNAse agar?

1) (+) : clear zone around inoculation line | 2) (-) : no clearing, green colored agar throughout

What are the purposes (or what types of medium) of BHI agar?

Supportive / enrichment media

What are the purposes (or what types of medium) of nutrient agar?

Supportive / enrichment media

What are the purposes (or what types of medium) of Thioglycollate broth?

Supportive / enrichment media

What are the purposes (or what types of medium) of Selenite F?

Enrichment / selective media

What is the meaning of SBA?

Sheep's (or sheep) Blood Agar

What is the meaning of Mac?

MacConkey Agar

What is the meaning of EMB?

Eosin Methylene Blue

What is the meaning of TCBS?

Thiosulfate Citrate Bile Salts and Sucrose

What is the meaning of LIA?

Lysine Iron Agar

What is the meaning of SIM?

Sulfide Indole Motility

What is the meaning of TSI?

Triple Sugar Iron

Culture Media Preparation (M) Flashcards

(70 cards)