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Cards In This Set
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Selective media that selects for Gram negatives
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Hektoen Enteric Agar(Salmonella and shigella)Eosin Methylene Blue(gut bacteria)Macconkey Agar(possible coliforms)
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Selective Media that selects for Gram Positive
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Phenyl Ethyl alcohol(Staph, strep, entero, lacto)Mannitol Salt Agar(StaphylococciColumbia CNA w/ 5% sheeps blood(Staph, strep, Enterococcus)
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Only Selective media that is not differential
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Phenylethyl alcohol agar
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PH indicators for selective media
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Phenol red-MSA plate yellow-red-pinknatural red-Macconkey red-colorless
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Columbia CNA with 5% sheep's blood agar contains
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Beef extract for carbon sourceyeast extract for b vitaminsColistin affects membrane intergrityNalidix acid affects DNA replication of gram negatives together affective against Pseudomonas and Proteus
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What does phenyl ethyl alcohol play
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It interferes with DNA synthesis in gram negative bacteria, used to screen out E. coli and Proteus
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Eosin Methylene Blue Agar
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Encourages growth of gut bacteria(enterobacteria, gram negative)
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What is in Eosin Methylene Blue agar
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Lactose and sucrose provide fermentable substrates to encourage growth of fecal coliforms
Eosin Y and methylene blue inhibit the growth of gram positives under acidic conditions, produce a purple and/or GREEN METALLIC SHEEN<==vigorous coliform |
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In Eosin Methylene Blue agar, this turns a pink coloration meaning a slow lactose fermenter
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Enterobacter aerogenes
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In both Columbia CNA in 5% sheep's blood agar and phenyl ethyl alcohol, this organism is definitely not allowed
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Proteus, in phenyl ethyl alcohol e. coli is also not grown
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Hektoen Enteric Agar
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Isolates S and S from other enterics, based on the ability to ferment lactose, sucrose and to reduce sulfur in hydrogen sulfide gas
reagent ferric ammonium hydrate is added and reacts with hydrogen sulfide to make a black precipitate(salmonella) bromthymol blue and acid fuchsin are color indicators bile salts make it selective(inhibiting gram +) |
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Macconkey agar
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Looks for possible coliforms(lactose fermenters)bile salts and crystal violet inhibit gram +neutral red dye is a pH indicator lactose fermenters turn dye red, if not it is colorless
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Oxidation fermentation test
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Tests on the ability to detect fermentative differences in oxidative metabolismcontains a HIGH SUGAR to PEPTONE ratiouses bromthymol blue indicator (yellow==>green if both hello, the sealed is FERMENTATIVE, other is oxidativeif sealed is green, then it is oxidative because it requires oxygen to changeif the both are green, then glucose is not metabolized
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Phenol red broth
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Ph indicator phenol red yellow-red-pinkcontains carbohydrate(Promotes fermentation) peptone(deamination of peptone AA's produces ammonia, turning it basic)
Measure the ability of an organism to ferment a particular sugar source |
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Methyl Red
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Identifies organisms that can perform a mixed acid fermentation and produce stable acid end products
MR +organisms lower the growth media's pHused to distinguish organisms from gut bacteria |
