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Indicators
detect pH change
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family that includes normal gastrointestinal microbiota, opportunists, and pathogens.
Enterobacteriaceae
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intestinal pathogens
- Salmonella
- Shigella
- some strains of E. coli
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SIM Media
- Sulfur Reduction
- Indole Production
- Motility
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Fermentation
release of acid (pH change)
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The _____ media contains ferrous sulfate (iron salts)that will turn ______when they combine with Hydrogen Sulfide (H2S) gas.
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The _____media is used to test for motility by using a needle and inoculating it with a stab. If the bacteria swim away from the line of inoculation(stab) they are _______. If the bacteria grow only along the stab line, they are ________.
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Indole can be detected by the addition of ________reagent which contains _______.
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When added to the SIM tube, the DMABA reacts with indole and turns ____ ____, indicating the presence of ______.
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______ _____ ____ is used to differentiate gram negative bacteria on the basis of citric acid utilization.
Simmon’s Citrate Agar SCA
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If bacteria grow in SCA, it means they used the ______as their ______source.
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In SCA organisms which have the enzyme _____, are able to utilize the sodium citrate and nitrogen sources and produce ammonia, which converts the agar to an alkaline pH and a ______color.
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In SCA the medium also contains the indicator, ______ blue, which is _____at pH ___ and ____ at pH ___ and above.
- bromthymol
- green
- 6.9
- blue
- 7.6
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Citrate Positive Color in SCA
blue
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Citrate Negative Color in SCA
green
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TSI
TRIPLE SUGAR IRON AGAR
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TSI medium contains three carbohydrates and differentiates bacteria on _______ of _____, _____, _____, or not.
- fermentation
- glucose
- sucrose
- lactose
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In TSI The indicator, _____ ___, is added to monitor the pH, and is ______in acidic pH and _____ in alkaline pH
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In TSI many bacteria but not all, produce gas during fermentation of sugars. This is observed by the presence of ___ ____ in the agar
air spaces
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Peptonization
When peptones (amino acids) are used for food
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In some cases, bacteria may ferment the sugars turning the medium yellow but use up all the sugar and turn to the peptones for food. When this happens the medium turns back to alkaline and red/pink. This is called ?
Conversion
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The organism fermented the glucose (yellow butt) and either the sucrose or lactose or both (yellow slant). The organism also produced gas during the fermentation process (break and air pocket in the agar).
Acid/Acid + Gas production
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The organism fermented the glucose (yellow butt) but could not ferment the other sugars when it exhausted the glucose source, instead the organism used the peptones and produced ammonia which results in an alkaline pH (pink-red slant).
Alkaline/ acid, no gas, No H2S production
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The organism fermented the glucose (yellow butt) but also used some of the peptones (pink-red slant). The organism also produced H2S (black precipitate).
Alkaline/acid + H2S Production
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Which enzyme is used in Urea Hydrolysis which hydrolyzes certain amino acids and urea to ammonia and carbon dioxide?
Urease
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Urease Agar Test results= pink=?
Urease enzyme Positive
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Urease Agar Test results= neutral=?
Urease enzyme Negative
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Differential media and rapid identification
Chromagar
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The ____ _____ is a differential stain which uses various dyes to differentiate two large groups of bacteria based on their cell walls aka _________ ______.
- Gram Stain
- peptidoglycan layer
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Gram Stain Procedure after Smear
- crystal violet stain--30 sec
- Rinse
- Gram’s iodine--1 min
- Rinse
- Gram’s alcohol-- 5-10 sec
- Rinse
- safranin--30-60 sec
- Rinse
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What happens when you decolorize too much or too little?
create false Gram negative results or false Gram positive results
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What stops the reaction with the decolorizer?
Distilled water
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Smear prep- preparing cells for gram stain by?
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Gram Stain primary dye?
crystal violet
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Gram Stain mordant?
iodine
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Gram Stain decolorizer?
Alcohol
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Gram Stain counter stain?
Safranin
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TSI uses? by what process?
- Needle
- zigzag on slant nd stab into bottom of agar
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SIM uses? by what process?
- Needle
- Stab into agar 2/3 down
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SCA uses? by what process?
- loop
- zigzag onto slant and stab into bottom of agar
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UREA uses? by what process?
- loop
- zigzag onto slant--no stab
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This enzyme is pink?
β-galactosidase
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This enzyme is blue?
β-glucosidase
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This enzyme turns brown/beige?
Tryptophan Deaminase
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- Purple Purple
- Purple Purple
- Purple No color
- Purple Pink
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Gram Stain Positive?
Gram Stain Negative?
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Gram + Cocci some staphylococci
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