Triple Sugar Iron Test Questions With Complete Solutions

For what bacteria would you use the TSI test? correct answer: Gram negative bacilli such as enterobacteriaceae. How would you identify an acidic slant? correct answer: If the slant goes from red to yellow on the phenol red. Why is there more lactose and sucrose in TSI agar than glucose? correct answer: In order to distinguish bacteria that can only ferment glucose from bacteria that ferment lactose and sucrose. It will also allow for greater acid production. TEST RESULTS: red slant/red butt correct answer: INTERPRETATION: no fermentation (NC) TEST RESULTS: red slant/yellow butt correct answer: INTERPRETATION: glucose fermentation (A) TEST RESULTS: yellow slant/yellow butt correct answer: INTERPRETATION: lactose and/or sucrose fermentation (A/A) TEST RESULTS: cracks or lifting in agar correct answer: INTERPRETATION: gas production (G) TEST RESULT: blackening o agar correct answer: INTERPRETATION: hydrogen sulfide production (H2S+) What is use to test TSI? correct answer: an agar slant that contains lactose and sucrose each in a 1% concentration and glucose in a 0.1% concentration.