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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.
Aerobic and anaerobic bacteria can be identified by growing them in test tubes of thioglycolate broth: 1: Obligate aerobes need oxygen because they cannot ferment or respire anaerobically.
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]).
When inoculated to a triple sugar iron slant, they react as follows: K/A, gas -, and H 2 S -. Indole reactions are mixed, positive and negative, with the exception of S. sonnei, which is always indole negative. Growth on Hektoen enteric agar produces bluish-green colonies for Shigella and bluish-green colonies with black centers for Salmonella.
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 .
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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 ...