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 TSI Agar?
TSI Agar is used for the differentiation of gram-negative enteric bacilli based on carbohydrate fermentation and the production of hydrogen sulfide. TSI Agar is used for the determination of carbohydrate fermentation and hydrogen sulfide production in the identification of gram- negative bacilli.
What does a a mean in TSI?
Summary of Possible TSI Reactions K = alkaline = Red; A = acid = Yellow; NC = No change; G = gas produced; H2S = hydrogen sulfide produced.
Why is the triple sugar iron agar test important?
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 three sugars are used in the TSI Agar?
TSI Agar contains three carbohydrates dextrose, lactose and sucrose. A color change from a reddish salmon to a pale yellow indicates carbohydrate fermentation; this acid production is detected by the Phenol Red pH indicator.
What is the principle of TSI test?
Principle. The triple sugar- iron agar test employing Triple Sugar Iron Agar is designed to differentiate among organisms based on the differences in carbohydrate fermentation patterns and hydrogen sulfide production.
How do you read a TSI test?
Expected results of TSI Agar test are:
- Alkaline slant/no change in butt (K/NC) i.e Red/Red = glucose, lactose and sucrose non-fermenter.
- Alkaline slant/Alkaline butt (K/K) i.e Red/Red = glucose, lactose and sucrose non-fermenter.
Does Salmonella produce gas in TSI?
On triple sugar iron agar (TSI) or Kligler iron agar (KIA) slants,S. Typhi characteristically produces an alkaline slant (red,“K”), an acid butt (yellow,“A”), and a small amount of blackening of the agar (H2S,+) at the site of the stab on the slant and in the stab line; no gas (G) is produced.
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.
Can E coli ferment glucose?
Escherichia coli is capable of fermenting glucose as are Proteus mirabilis (far right) and Shigella dysenteriae (far left).
Why is there more lactose and sucrose than glucose in TSI Agar?
Since lactose and sucrose are present in much higher concentrations than glucose, acid formation in the butt is due to these sugars, while the acid formation from glucose is suppressed by a rapid oxidation of the small amount of acid in the slanted area of the tube, resulting in a neutral or alcaline pH reaction when
For what bacteria would you use the TSI test quizlet?
-the TSI test is designed to differentiate among the different groups or genera of the Enterobacteriaceae, which are all gram-negative bacilli capable of fermenting glucose with the production of acid, and to distinguish the Enterobacteriacase from other gram-negative intestinal bacilli.
Is lactose a sugar?
Lactose is a type of sugar, naturally found in milk and dairy products. In the intestine, lactose is transformed by lactase, an enzyme, into glucose and galactose, both simpler sugars, which are used by our body for energy and various functions.
How is gas formation indicated in TSI Agar?
Organisms showing this reaction are defined as non-fermenters, and derive their nutrients from the peptones present in the medium. The formation of CO2 and hydrogen gas (H2) is indicated by the presence of bubbles or cracks in the agar or by separation of the agar from the sides or bottom of the tube.