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24 Cards in this Set
- Front
- Back
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enriched media
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basal growth media with one or more growth factors added (enrichments)
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What are some growth factors?
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blood, carbs, amino acids, vitamins, and nacl
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what characterizes fastidious bacteria
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the need for additional nutrients in their media/environment
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what is an auxotroph?
for e.g., |
it is derived from a prototroph which grows on a basal media.
-a bacterium which has mutated and developed a specific growth requirement that it previously synthesized itself e.g. Streptococcus |
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halophile
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salt-loving bacterium;
e.g., Vibrionolipherocous |
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enrichment media
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-suppresses normal flora while enhancing pathogen growth
-usually for stool specimens |
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What does a selective media do?
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selects for the growth of some bacteria while inhibiting the growth of others.
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Some general agents of a Selective media
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Antibiotics, Dyes, Chemicals, pH changes
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What is the purpose of a selective media?
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to better identify a bacterium
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What is the purpose of an Enteric Media?
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to isolate pathogens of the intestine.
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What are ALL enteric media selective for?
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Gram negative bacilli
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What does a Low selectivity Enteric media ALLOW to grow?
Moderately selective? HIghly selective? |
-All GNB, whether pathogen or not.
-Moderately inhibits some normal flora. -Highly inhibits almost all normal flora and sometimes the pathogen itself too! |
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What is the purpose of a differential media?
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to differentiate between bacteria, based on some charactistic which is usually based upon a biochemical reaction.
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What kind of media are pH indicators in, and what do they do?
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in DIFFERENTIAL; they register the difference between bacteria.
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what are the three main ways for bacteria to produce energy?
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-Fermentation
-Aerobic respiration -Anaerobic respiration |
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catabolism
anabolism |
break down of molecules into energy
buildup of molecules using energy |
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how to report hemolysis:
gamma alpha beta |
gamma - no hemolysis
alpha - incomplete hemolysis; green-brown discoloration beta - complete hemolysis; clear, colorless zone around colony |
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why stab the plate for hemolysis?
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so if colonies being streaked are oxygen labile they will have the correct atmosohere to grow in
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most common types of enrichment media:
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-selenite
-GN broth -tetrathionate |
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additives that make a medium selective:
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dyes, bile salts, pH adjustments, antibiotics
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CA stands for
and does what |
chocolate agar
supports growth of fastidious bacteria |
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what plates are low selectivity?
how do they work? |
LEMB and McConkey's.
allow all gnb to grow; do not select for enteric pathogens. |
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What plates are moderately selective?
How do they work? |
-xld
-ss -he they select for GNB, and contain chemicals that inhibit growth of normal gnb flora. |
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what plates are highly selective?
how do they work? |
bismuth sulfite agar
brillian green agar contain chemicals which inhibit virtually all enteric non-pathogens. |
