Term
| What type of medium is Bile Esculin Agar? |
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Definition
| undefined, selective, differential containing beef extract, digest of gelatin, esculin, oxgall(bile), and ferric citrate. |
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Term
| What is the selective agent included in bile esculin agar? |
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Definition
| The bile, which separates the streptococcus bovis group and enterococci from other streptococci. |
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Term
| Among the streptococci, what organisms can tolerate bile and hydrolyze esculin? |
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Definition
| Members of the Streptococcus bovis group: S. equinas, S. gallolyticus, S. infantarius, S. alactolyticus |
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Term
| In the esculin bile agar test what reacts to form the dark brown precipitate indicating a positive result? |
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Definition
| Esculetin reacts with the Fe3+ ions from ferric citrate. |
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Term
| What kind of media is Simmons Citrate Agar? |
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Definition
| Defined medium that contains sodium citrate as the sole carbon source and ammonium phosphate as the sole nitrogen source. |
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Term
| What indicator is added to Simmons Citrate Agar? And what are the color indicators? |
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Definition
| Bromothymol blue dye is added and is green at pH 6.9, and blue at pH 7.6. |
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Term
| What indicates a positive citrate test result? |
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Definition
Blue agar (pH over 7.6)
Growth |
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Term
| In the citrate test what causes the increase in alkalinity? |
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Definition
| Bacteria that survive in the medium and utilize the citrate also convert ammonium phosphate to NH3 and ammonium hydroxide, both of which alkalinize the agar. |
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Term
| In the decarboxylation test what pH indicator is included in the medium? |
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Definition
| Bromcresol purple which is purple at pH 6.8 and above and yellow below pH 5.2 |
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Term
| What is a positive result in the decarboxylation test? |
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Definition
Purple, which indicates that the organism produces
the specific decarboxylase enzyme |
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