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23 Cards in this Set
- Front
- Back
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several media are designed to |
yield more than one biochemical reaction |
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more commonly used media |
SIM media triple sugar iron agar(TSI) Kliger's Iron agar(KIA) |
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SIM |
derives its name from three reactions 1. production of H2s from sulfur-containing amino acids 2. indole production 3. motility |
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check for motility by |
observing migration of the inoculum from the stab line through the semisolid medium |
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a blackening of the medium indicates |
liberation of H2S |
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after the + of Kovac's reagent |
a red color indicates the presence of indole |
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single media/multiple tests |
used primarily for differentiation of gram - enteric bacteria |
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materials/cultures used for single media or multiple tests
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SIM agar Escherichia coli Pseudomonas aeruginosa Salmonella typhimurium |
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Kliger's Iron Agar(KIA) and Triple Sugar Iron Agar(tsi) |
widely used in the ID of gram negative bacteria particularly enterobacteriacease |
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KIA and TSI are ID except |
TSI contains sucrose in addition to the dextrose and lactose in KIA
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TSI and KIA are poured as |
slants and are innoculated with a stab to the butt followed by a streak of the slant surface |
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Bacteria therefore are exposed to both |
an anaerobic environent (Butt) and an aerobic one (slant) |
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Indicator in TSI and KIA |
phenol red |
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nonfermenter bacteria example and description |
ex. pseudomonas grow on the slant by the aerobic degradation of protein components in the medium to alkaline products the slant and butt will stay red |
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if bacteria ferment dextrose but NOT sucrose or lactose |
Acid is produced in the slant and the butt and medium turns yellow |
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dextrose is used up within |
12 hours |
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bacteria at the surface continue to grow by |
degrading proteins |
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by 18 to 24 hours |
the alkaline end produce cause the medium in the slant to revert to a red solor |
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Shigella |
-non lactose fermenter the alkaline end produce cause the medium in the slant to revert to a red solor |
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can ferment lactose and/or sucrose as well as dextrose |
the slant and butt will remain yellow after prolonged incubation -the high [lactose] keeps the lant acidic despite the production of alkaline products by protein degradation |
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hydrogen sulfide production indicators in TSI and KIA |
sodium thiosulfate and ferrous sulfate |
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salmonella sp |
dextrose fermenter lactose nonfermenter yields an acid butt with a black precipitate and an alkaline slant |
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A. pseudomonas aeroginosa. GLUC(-), LAC/SUC(-), H2S(-) B. Escherichia Coli Gluc(+), Lac/Suc(+), H2S(-) C. Salmonella typhimurium: Gluc (+), Lac/Suc(-), H2S(+) D. Shigella Boydii-Gluc(+), lac/suc(-), H2S(-) |
