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The TSI slant is a test tube that contains agar, a pH-sensitive dye , 1% lactose, 1% sucrose, 0.1% glucose, [2] and sodium thiosulfate and ferrous sulfate or ferrous ammonium sulfate. All of these ingredients are mixed together, heated to sterility, and allowed to solidify in the test tube at a slanted angle.
A TSI slant is often used to distinguish nonfermenting Pseudomonas species from enteric pathogens in faecal specimens. [citation needed] When P. aeruginosa is isolated from a normally sterile site (blood, bone, deep collections), it is generally considered dangerous, and almost always requires treatment.
The urease agar slant is used to measure an organism’s ability to produce urease, an enzyme capable to digesting urea in carbon dioxide and ammonia through hydrolysis. Because ammonia is alkaline, the media contains phenol red, an indicator that changes from orange to pink when a pH increases above 8.1.
Inoculation of a TSI slant shows an alkaline slant and acidic, but with no gas, or H 2 S production. Following incubation on SIM, the culture appears nonmotile with no H 2 S production. Addition of Kovac's reagent to the SIM tube following growth typically indicates no indole formation (serotypes 2, 7, and 8 produce indole [5]).
Cetrimide also enhances the production of Pseudomonas pigments such as pyocyanin and pyoverdine, which show a characteristic blue-green and yellow-green colour, respectively. [ 3 ] [ 4 ] Cetrimide agar is widely used in the examination of cosmetics, pharmaceuticals and clinical specimens to test for the presence of Pseudomonas aeruginosa .
Simmons’ agar can be bought from suppliers as ready-made powders or slants. A slant is prepared by adding the heated agar to a test tube and allowing it to solidify at a slanted angle. To transfer cells from a sample to the agar, a sterilized needle is used to select a distinct colony from the sample and to streak across the agar surface, as ...
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Blood agar plates (BAPs) contain mammalian blood (usually sheep or horse), typically at a 5–10% concentration. BAPs are enriched, and differential media is used to isolate fastidious organisms and detect hemolytic activity. β-Hemolytic activity will show lysis and complete digestion of red blood cell contents surrounding a colony.