microbiology tests for gram negative/enteric bacteria Flashcards

Terms Definitions
tripple sugar iron
pH indicator is phenol red, as well as ferric ammonium sulfate
screens for sugar metabolism (glucose and/or disacharide); acid production; hydrogen sulfide production
results of this test allow you to determine the presence of the enzymes sucrase and or lactase
yellow/yellow TSI results on top and in stab: initial use of glucoseand secondary use of one or both disacharides
red/yellow TSI results: initial use of glucose, but no disacharide use
red/red TSI results: no growth or aerobic non-fermenter
red color on TSI means productionof alkaline wastes from protien digestion
yellow color change on TSI results indicates acid production from sugar metabolism
TSI: bubbles and or cracking
gas production (CO2 or H2)
TSI results: black color
H2S production
pH indicator is bromothymol blue
screens for the presence of enzyme citrate permease and citrase, needed for metabolism of citrate
determines if organism can use citrate as its sole metabolic (carbon) energy source
Citrate- bright blue
indicates organism has used citrate as a nutrient source and produced alkaline end products
Citrate-green color
organism couldnt use citrate, negative test
Durham tubes
phenol red is pH indicator
Durham tubes
screens for ability of an organism to use a particular sugar as a metabolic energy source; the production of gas
Durham tubes
production of acid OR alcohol end products
Durham tubes-lemon yellow
organism produces acids as fermentation end products
Durham tubes- red/orange
alcohol production from fermentation or aerobic respiration with no fermentation
Durham tubes-bubbles
gas production, primarily CO2
methyl red pH indicator; Berritts reagent added after incubation
screens for the end product of glucose metabolism:acetoin production or mixed acids
MR-VP- yellow tube
positive test, produced mixed acids
MR-VP- red ring after reagent added
production of acetoin from glucose metabolism
SIM deep
sulfer indole motility
SIM deep
detect for ability of organismto break down the amino acid cysteine; to break down the amino acid tryptophan; ability of organism to move in media
SIM deep
Kovac's reagent used
SIM deep- black precipitate
H2S production
SIM deep- red ring after Kovacs reagent
production of indole and a positive test, digestion of tryptophan
SIM deep- feathering away or cloudiness from stab line
positive test for motility, flagella present
Urea slant
phenol red pH indicator
Urea slant
determine if organism can break down urea or not, if urease is present
Urea slant- bright pink
positive for urea metabolism, breakdown of urea to ammonia, causing rise in pH
phenylaline slant
determine if organism can deaminate the amino group from the phenylaline amino acid
phenylaline slant
ferric chloride is the reagent
phenylaline slant- yellow color after ferrous chloride added
negative for phenylaline deamination
phenylaline slant- green color after ferrous chloride added
positive for the enzyme phenylaline deaminase
lysine/ornithine broth
bromocresol purple is pH indicator
lysine/ornithine broth
determines if organism has ability to decarboxylate of lysine OR ornithine
lysine/ornithine broth- purple
positive for lysine or ornithine metabolism: presence of lysine or ornithine decarboxylase enzyme
lysine/ornithine broth- yellow color
negitive for metabolism or ornithine or lysine
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