The Triple Sugar Iron (TSI) test is a microbiological test roughly named for its ability to test a microorganism’s ability to ferment sugars and to produce hydrogen sulfide Sulfide is an inorganic anion of sulfur with the chemical formula S²⁻ or a compound containing one or more S²⁻ ions. Solutions of sulfide salts are corrosive. Sulfide also refers to chemical compounds large families of inorganic and organic compounds, e.g. lead sulfide and dimethyl sulfid…Sulfide
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Salmonella is a genus of rod-shaped gram-negative bacteria of the family Enterobacteriaceae. The two species of Salmonella are Salmonella enterica and Salmonella bongori. Salmonella enterica is the type species and is further divided into six subspecies that include over 2,500 serot…
Shigella
Shigella is a genus of Gram-negative, facultative aerobic, non-spore-forming, nonmotile, rod-shaped bacteria genetically closely related to E. coli. The genus is named after Kiyoshi Shiga, who first discovered it in 1897.
What is the triple sugar iron test (TSI)?
The Triple Sugar Iron ( TSI) test is a microbiological test roughly named for its ability to test a microorganism’s ability to ferment sugars and to produce hydrogen sulfide. [1] It is often used to differentiate enteric bacteria including Salmonella and Shigella.
What is TSI agar test?
Triple Sugar Iron (TSI) Agar test is a combo test and useful for identification of mainly gram-negative bacteria, on the basis of following tests- fermenter or oxidizer or non-utilizer of carbohydrates like glucose, lactose, or sucrose
What is the pH of triple sugar iron TSI agar?
Composition of Triple Sugar Iron (TSI) Agar Final pH (at 25°C): 7.3 +/- 0.2 Principle of Triple Sugar Iron (TSI) Agar The TSI agar is a special medium with multiple sugars constituting a pH-sensitive dye (phenol red), 1% lactose, 1% sucrose, 0.1% glucose, as well as sodium thiosulfate and ferrous sulfate or ferrous ammonium sulfate.
What is triple sugar iron agar used for?
Triple-sugar iron agar medium for the identification of the intestinal group o f bacteria. J. Bacteriol. 49:516-517. 3. Kliger, I. J.1917. A simple medium for the differentiation of members of the typhoid-paratyphoid group.
What is the purpose of the Triple sugar iron test?
Triple sugar iron agar, or TSI, is a differential medium that tests a bacterial strain for several different properties at once. It tests for acid and gas production from the fermentation of glucose and sucrose and/or lactose and for the production of hydrogen sulfide.
What is the importance of the TSI slant in diagnostic microbiology?
Triple Sugar Iron Agar (TSI Agar) is used for the differentiation of gram-negative enteric bacilli based on carbohydrate fermenta- tion and the production of hydrogen sulfide. Hajna developed the formulation for TSI Agar by adding sucrose to the double sugar (dextrose and lactose) formulation of Kligler Iron Agar.
What three sugars are used in the triple sugar iron TSI Agar?
TSI Agar contains three carbohydrates dextrose, lactose and sucrose.
How some bacteria are able to produce the black precipitate on TSI Agar slant?
Sodium thiosulfate in the medium is reduced by some bacteria to hydrogen sulfide (H 2S), the latter reacts with ferric ions in the medium to produce iron sulfide, a black insoluble precipitate.
What bacteria would you use the TSI test?
The Triple Sugar Iron (TSI) test is a microbiological test roughly named for its ability to test a microorganism's ability to ferment sugars and to produce hydrogen sulfide. It is often used to differentiate enteric bacteria including Salmonella and Shigella.
What is the purpose of the TSI test quizlet?
What is the purpose of the Triple Sugar-Iron test? The TSI test is designed for the rapid separation and presumptive identification of enteric organisms. The Triple sugar-iron medium contains a lower concentration of glucose than of lactose and sucrose to allow for detection of the utlization of this substrate only.
How do you do the TSI test in microbiology?
1:312:37Triple Sugar-Iron Agar Test - Amrita University - YouTubeYouTubeStart of suggested clipEnd of suggested clipThe cap and flame the mouth of the tube stab the needle containing the pure culture into the mediumMoreThe cap and flame the mouth of the tube stab the needle containing the pure culture into the medium in the butt of the TSI two and then shriek back and forth along the surface of the slab.
How can a TSI slant be used to identify different enteric bacteria?
It is used to differentiate enterics based on the ability to reduce sulfur and ferment carbohydrates. As with the phenol red fermentation broths, if an organism can ferment any of the three sugars present in the medium, the medium will turn yellow.
What is slant in microbiology?
An agar slant tube (or simply an agar slant) is a screw-capped culture tube partly filled with an agar mix such as nutrient agar, R2A agar, or TSA (figure 1). To make it a slant tube the agar is allowed to cool with the tube laying at an angle, resulting in a large surface area for spreading a culture.
What is the purpose of TSI test for college?
The TSI Assessment (TSIA) is part of the Texas Success Initiative enacted by the Texas State Legislature and designed to determine a student's readiness for college-level coursework in the general areas of reading, writing, and mathematics.
What is the purpose of carbohydrate fermentation test?
The carbohydrate fermentation test is used to determine whether or not a bacteria can utilize a certain carbohydrate. It tests for the presence of acid and/or gas produced from the fermentation of a single particular carbohydrate.
What is triple sugar iron agar?
‘ Triple Sugar Iron Agar ‘, you have to remember that it’s a test which has three sugar (lactose, sucrose, and glucose) and also iron; and it contains agar as solidifying agent (TSI is a semi-solid media having slant and butt).
What is the ratio of glucose to lactose in TSI?
TSI is similar to Kligler’s iron agar (KIA), except that Kligler’s iron agar contains only two carbohydrates: glucose (0.1%) and lactose (1%) .
How to inoculate TSI agar?
Inoculate TSI agar by first stabbing through the center of the medium to the bottom of the tube and then streaking on the surface of the agar slant.
How to dissolve agar in a tube?
Boil to dissolve the agar and dispense into tubes.
What color is ferrous sulfide?
if H 2S is produced, the black color of ferrous sulfide is seen.
Does TSI agar contain sucrose?
Inoculation in TSI agar. Addition of sucrose in TSI agar permits earlier detection of coliform bacteria that ferment sucrose more rapidly than lactose. Adding sucrose also aids the identification of certain gram-negative bacteria that could ferment sucrose but not lactose.
What is a triple sugar iron test?
The Triple Sugar Iron ( TSI) test is a microbiological test roughly named for its ability to test a microorganism’s ability to ferment sugars and to produce hydrogen sulfide. [1] It is often used to differentiate enteric bacteria including Salmonella and Shigella.
What is TSI agar medium?
TSI agar medium was developed based on Kligler’s iron agar, which had been used for the determination of lactose-fermentative bacteria, by addition of sucrose to be able to detect sucrose-fermentative bacteria, also.
Why is my TSIA yellow?
The acid in the medium cause the ph indicator phenol red, to change its colour to yellow. Thus, after 6 hours of incubation both the slant and butt of TSIA that has been inoculated with a glucose fermenter will appear yellow.
What is a Tsi slant?
The TSI slant is a test tube that contains agar, a pH-sensitive dye (phenol red), 1% lactose, 1% sucrose, 0.1% glucose, 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.
How are test bacteria inoculated?
The test bacteria is inoculated aseptically, preferably in a laminar flow chamber, into the slants by stabbing into the butt and streaking on the surface of the slants with the help of a flame- sterilised needle. The needle is sterilised after each inoculation.
How much water is in a Tsi agar?
The ingredients of TSI agar medium (containing the 3 sugars and iron as the main components) or its ready-made powder required for 100 ml of the medium is weighed and dissolved in 100 ml of distilled water in a 250 ml conical flask by shaking and swirling.
How do bacteria gain energy?
Enter bacteria and other glucose fermenter first begin to metabolize glucose as glucose utilizing enzymes are present constitutively and bacteria can gain the most energy by using simplest sugar. All other sugar must be converted to glucose before they enter the EMP.
What is triple sugar iron agar?
The triple sugar- iron agar is designed to differentiate among organisms based on the differences in carbohydrate fermentation patterns and hydrogen sulfide production.
What is Tsi agar?
The Triple Sugar Iron (TSI) agar is a culture medium named for its ability to test a microorganism’s ability to ferment sugars and to produce hydrogen sulfide.
What is the principle of triple sugar iron?
Principle of Triple Sugar Iron (TSI) Agar. The TSI agar is a special medium with multiple sugars constituting a pH-sensitive dye (phenol red), 1% lactose, 1% sucrose, 0.1% glucose, as well as sodium thiosulfate and ferrous sulfate or ferrous ammonium sulfate. All of these ingredients when mixed together and allowed solidification ...
How long does it take to read TSI agar?
TSI Agar must be read within the 18-24 hour stated incubation period. A false-positive reaction may be observed if read too early. A false-negative reaction may be observed if read later than 24 hours. An organism that produces hydrogen sulfide may mask acid production in the butt of the medium.
How to inoculate a TSI?
Inoculate TSI by first stabbing through the center of the medium to the bottom of the tube and then streaking the surface of the agar slant. Leave the cap on loosely and incubate the tube at 35°-37°C in ambient air for 18 to 24 hours.
What does a bubble in an agar mean?
Gas production: Bubbles or cracks in the agar indicate the production of gas ( formation of CO2and H2)
How long to incubate a syringe?
Leave the cap on loosely and incubate the tube at 35°-37°C in ambient air for 18 to 24 hours.
Principle of Triple Sugar Iron (TSI) Agar Test
The Triple Sugar Iron (TSI) Agar contains casein and meat peptones, phenol red as the pH indicator, 0.1% glucose, 1% lactose, and 1% sucrose for fermentation. Ferric or ferrous ions and sodium Thiosulphate are present to detect hydrogen Sulphide production.
Result and interpretation of Triple Sugar Iron Agar Test
Yellow (Acid)/ Yellow (Acid), Gas, H 2 S: Lactose/Sucrose fermenter, H 2 S producer.
Limitations of TSI Test
Do not read the TSI test before 18 hours, since false readings of acid in the slant may result.
Keynotes
Kligler’s Iron Agar (KIA) test only differs from the Triple Sugar Iron agar (TSI) test due to lacking sucrose in its composition.
Further Readings
Cowan & Steel’s Manual for identification of Medical Bacteria. Editors: G.I. Barron & R.K. Felthani, 3rd ed 1993, Publisher Cambridge University Press.