What is TSI Agar used for?
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.
How do you read TSI results?
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….
| Results (slant/butt) | Symbol | Interpretation |
|---|---|---|
| Yellow/yellow with bubbles | A/A,G | Glucose and lactose and/or sucrose fermentation; Gas produced |
What is the color or TSI for salmonella?
Result Interpretation on Triple Sugar Iron (TSI) Agar
| Organisms | Growth |
|---|---|
| Salmonella Typhi | Red slant, yellow butt, no gas production; H2S produced |
| Salmonella Typhimurium | Red slant, yellow butt, gas production; H2S produced |
| Shigella flexneri | Red slant, yellow butt, gas negative, H2S not produced |
How does gas Look in the TSI test?
Carbohydrate fermentation is indicated by the production of gas and a change in the colour of the pH indicator from red to yellow.
What do yellow vs pink color changes mean in the triple sugar iron agar test?
Three sugars are found in TSIA: glucose, sucrose, and lactose. If any of the sugars can be used, the microbe will accumulate acidic byproducts. In a positive test, the pH indicator in the medium changes color from its normal red to yellow, indicating acid production.
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.
Is Salmonella typhi citrate positive?
When Simmons Citrate agar is inoculated with Salmonella typhimurium , the medium turns royal blue. This is a positive result for the citrate test. When Simmons Citrate agar is inoculated with Escherichia coli , the medium remains green. This is a negative result for the citrate test.