Skip to main content

Triple Sugar Iron Test

By
The Triple Sugar Iron (TSI) Test 

To determine the ability of an organism to ferment glucose, lactose, and sucrose, and their ability to produce hydrogen sulfide.
Principle
The Triple Sugar Iron (TSI) test is a microbiological test named for its ability to test a microorganism’s ability to ferment sugars and to produce hydrogen sulfide. An agar slant of 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 is used for carrying out the test. 

. Due to the building of acid during fermentation, the pH falls. The acid base indicator Phenol red. is incorporated for detecting carbohydrate fermentation that is indicated by the change in color of the carbohydrate medium from orange red to yellow in the presence of acids.  In case of oxidative decarboxylation of peptone, alkaline products are built and the pH rises. This is indicated by the change in colour of the medium from orange red to deep red. Sodium thiosulfate and ferrous ammonium sulfate present in the medium detects the production of hydrogen sulfide and is indicated by the black color in the butt of the tube.
Composition of Triple Sugar Iron Test

Final pH 7.3 +/- 0.2 at 25ºC.
Method

1.    With a straight inoculation needle, touch the top of a well-isolated colony.
2.    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.
3.    Leave the cap on loosely and incubate the tube at 35°-37°C in ambient air for 18 to 24 hours.
4.    Examine the reaction of medium.
Expected Results
  • An alkaline/acid (red slant/yellow butt) reaction: It is indicative of dextrose(Glucose) 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 
  • Gas production: Bubbles or cracks in the agar indicate the production of gas ( formation of CO2and H2)
Triple sugar iron agar. A, Acid slant/acid butt with gas, no H2S (A/A). B, Alkaline slant/acid butt, no gas, H2S-positive (K/A H2S+). C, Alkaline slant/alkaline butt, no gas, no H2S (K/K). D, Uninoculated tube.
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.
  • It is use for compare with 

    Kligler's Iron Agar (KIA) of sucrose's microbial.



References
https://www.time2026end.com/
Labels:

Comments

Post a Comment

Popular posts from this blog

Microscopic examination of urine

By
Microscopic examination of urine expressing microscopically observed leucocytes, erythrocytes, and casts in urine, both with centrifugation, Testing  Specimen: Urine patient Equipment: tube, centrifuge,timer,pipette transfer,microscope side, cover slip,microscopy Testing: Urine take in tube 3/4 of tube Take to centrifuge 3000rmp/1mn at 5 minutes Decant out of above liquid  Pipette transfer sucks sediment take on microscope side and cover slip Examination with microscopic Result: Reference: www.time2026end.com Laboratory book livre de lavoratorie 1th edition 1999 https://www.google.com/url?sa=i&url=http%3A%2F%2Fe-learning.studmed.unibe.ch%2FUroSurf_EN%2Ftheory%2Fsedimethods2.html%3Furosurf%7Ctheory%7Csediment%7Csedimethods%7C2&psig=AOvVaw0KIQHg49jHVyHFdvza_3TL&ust=1582250323839000&source=images&cd=vfe&ved=0CAMQjB1qFwoTCNDK8fmD3-cCFQAAAAAdAAAAABAg
Post a Comment
Read more

MacConkey Agar

By
MacConkey Agar MacConkey agar  is a selective and differential media used for the isolation and differentiation of non-fastidious gram-negative rods, particularly members of the family Enterobacteriaceae . Composition MacConkey agar is used for the isolation of gram-negative enteric bacteria and the differentiation of lactose fermenting from lactose non-fermenting gram-negative bacteria.  Pancreatic digest of gelatin  and  peptones (meat and casein)  provide the essential nutrients, vitamins and nitrogenous factors required for growth of microorganisms.  Lactose monohydrate  is the fermentable source of carbohydrate. The selective action of this medium is attributed to  crystal violet  and  bile salts,  which are inhibitory to most species of gram-positive bacteria.  Sodium chloride  maintains the osmotic balance in the medium. ...
Post a Comment
Read more