Preparation of TSI Agar
- Combine the ingredients, and adjust the pH to 7.3
- Boil to dissolve the agar
- Dispense it into tubes
- Sterilize by autoclaving at 121°C for 15 minutes
- Cool in a slanted position to give a 2.5 cm butt and a 3.8 cm slant.
What is a TSI slant test?
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 do you test for TSI on Triple sugar iron agar?
Procedure for Triple Sugar Iron Agar (TSI) Test. With a sterilized straight inoculation needle touch the top of a well-isolated colony. 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 do you make a TSI tube?
Another basic understanding is TSI tube contains butt (poorly oxygenated area on the bottom) slant (angled well-oxygenated area on the top). Combine the ingredients, and adjust the pH to 7.3 Boil to dissolve the agar and dispense into tubes. Cool in a slanted position to give a 2.5 cm butt and a 3.8 cm slant.
How do you inoculate a slant test?
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 do I prepare TSI Agar slant?
Preparation of TSI AgarCombine the ingredients, and adjust the pH to 7.3.Boil to dissolve the agar.Dispense it into tubes.Sterilize by autoclaving at 121°C for 15 minutes.Cool in a slanted position to give a 2.5 cm butt and a 3.8 cm slant.
How do I prepare for TSI media?
Preparation and Method of Use Suspend 64.42 grams (the equivalent weight of dehydrated medium per liter) in 1000 ml purified distilled water. Heat to boiling to dissolve the medium completely. Mix well and distribute into test tubes.
What does the slant of TSI test for?
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.
How do you inoculate a TSI slant?
Use a straight inoculating needle to pickup an isolated colony. Inoculate the TSI slant by first stabbing the butt down to the bottom, withdraw the needle, and then streak the surface of the slant. Use a loosely fitting closure to permit access of air. Read results after incubation at 37°C for 18 to 24 h.
How do I take the TSI test?
TSI Assessment Process OverviewContact one of the following for a test referral: ... Complete your Pre-Assessment Activity (PAA) online through the College Board website. ... Request a date to take your test and pay. ... Take the TSI.More items...•
What type of media is TSI?
Triple sugar iron agar (TSI) is a differential medium that contains lactose, sucrose, a small amount of glucose (dextrose), ferrous sulfate, and the pH indicator phenol red. It is used to differentiate enterics based on the ability to reduce sulfur and ferment carbohydrates.
How is the TSI scored?
The TSI Assessments measure college readiness in reading, writing, and math. The scores are used for college placement purposes. Examinees take a placement test of 20-25 items per section, which produces a numeric scale score ranging from 310 to 390.
Can a mixed culture be used to inoculate a TSI slant?
A pure culture is essential when inoculating Triple Sugar Iron Agar. If inoculated with a mixed culture, irregular observations may occur. Further biochemical tests and serological typing must be performed for definite identification and confirmation of organisms.
How is triple sugar iron agar inoculated quizlet?
how are TSI inoculated? -first, the butt of the slant is stabbed by pushing the needle into the agar to within 0.5 cm of the bottom of the tube. -then, as the needle is removed from the butt, the surface of the slant is streaked by dragging the needle lightly across the slanted surface of the agar in a zig-zag motion.
Why is sucrose added in TSI?
Why Sucrose is added in TSI? 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.
How do I pass the TSI essay?
The TSI essay will be evaluated on your organization, focus, development and support, sentence structure, and mechanical conventions. Fortunately, your essay is only required to be 300-600 words in length....Admit the complexity of the issue.Introduce your example.Describe it.Explain how it fully supports your thesis.
How hard is TSI?
The difficulty of the TSI math test questions depends on the test taker. Because the TSI is a computer-adaptive test, the next question will be more difficult if the test taker answers the question correctly. However, the more difficult questions are answered, the higher the possible score will be.
How do I study for the TSI math portion?
How do I study for the TSI Math?Pre-Tests. Start each section with a short pre-test to determine if you already know the material.Instruction and Guided Practice. Use video and audio explanations as a core component of your TSI math test prep.Practice Tests. Make sure you're ready for the real thing.
Can you use a calculator on the TSI?
No. Calculators are not allowed. Additionally, no study materials or other reference materials may be used during the test.
Composition of Triple Sugar Iron Agar (TSI)
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.
Interpretation of Triple Sugar Iron Agar Test
If lactose (or sucrose) is fermented, a large amount of acid is produced, which turns the phenol red indicator yellow both in the butt and in the slant. Some organisms generate gases, which produce bubbles/cracks on the medium.
Introduction
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.
Principle
Triple Sugar Iron Agar (TSIA) contains 3 sugar glucose (dextrose) sucrose, lactose in the ratio of1: 1:10 as the source of carbon as its name suggest.
Procedure
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.
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.
Preparation and Method of Use
Suspend 64.42 grams (the equivalent weight of dehydrated medium per liter) in 1000 ml purified distilled water.
Uses of Triple Sugar Iron (TSI) Agar
It is used to determine the ability of an organism to ferment glucose, lactose, and sucrose, and their ability to produce hydrogen sulfide.
Limitations of Triple Sugar Iron (TSI) Agar
It is recommended that biochemical, immunological, molecular, or mass spectrometry testing be performed on colonies from pure culture for complete identification.
Composition
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 .
Interpretation of results
Bacteria that ferment any of the three sugars in the medium will produce byproducts. These byproducts are usually acids, which will change the color of the red pH-sensitive dye (phenol red) to a yellow color.
Principle
Method
- With a straight inoculation needle, touch the top of a well-isolated colony.
- 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.
- With a straight inoculation needle, touch the top of a well-isolated colony.
- 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.
- Examine the reaction of medium.
Expected Results
- An alkaline/acid (red slant/yellow butt) reaction:It is indicative of dextrose fermentation only.
- An acid/acid (yellow slant/yellow butt) reaction:It indicates the fermentation of dextrose, lactose and/or sucrose.
- An alkaline/alkaline (red slant, red butt) reaction:Absence of carbohydrate fermentation results.
- An alkaline/acid (red slant/yellow butt) reaction:It is indicative of dextrose fermentation only.
- An acid/acid (yellow slant/yellow butt) reaction:It indicates the fermentation of dextrose, lactose and/or sucrose.
- An alkaline/alkaline (red slant, red butt) reaction:Absence of carbohydrate fermentation results.
- Blackening of the medium: Occurs in the presence of H2
Uses
- The test is used primarily to differentiate members of the Enterobacteriaceae family from other gram-negative rods.
- It is also used in the differentiation among Enterobacteriaceae on the basis of their sugar fermentation patterns.
Limitations
- It is recommended that biochemical, immunological, molecular, or mass spectrometry testing be performed on colonies from pure culture for complete identification.
- It is important to stab the butt of the medium. Failure to stab the butt invalidates this test. The integrity of the agar must be maintained when stabbing. Caps must be loosened during this test or...
- It is recommended that biochemical, immunological, molecular, or mass spectrometry testing be performed on colonies from pure culture for complete identification.
- It is important to stab the butt of the medium. Failure to stab the butt invalidates this test. The integrity of the agar must be maintained when stabbing. Caps must be loosened during this test or...
- 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 ho...
- An organism that produces hydrogen sulfide may mask acid production in the butt of the medium. However, hydrogen sulfide production requires an acid environment, thus the butt p…
References
- Tille P.M. 2014. Bailey and Scott’s diagnostic microbiology. Thirteen edition. Mosby, Inc., an affiliate of Elsevier Inc. 3251 Riverport Lane. St. Louis. Missouri 63043
- https://catalog.hardydiagnostics.com/cp_prod/Content/hugo/TripleSugarIronTSIAgar.htm
- , et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.
- https://vlab.amrita.edu/?sub=3&brch=76&sim=216&cnt=1
Similar Posts